- An alternative approach to establishing trade-offs among greenhouse gases
Manne, AS; Richels, RG*
Nature, vol. 410, no. 6829, pp. 675-677, 5 Apr 2001
The Kyoto Protocol permits countries to meet part of their emission reduction obligations by cutting back on gases other than CO sub(2). This approach requires a definition of trade-offs among the radiatively active gases. The Intergovernmental Panel on Climate Change has suggested global warming potentials for this purpose, which use the accumulated radiative forcing of each gas by a set time horizon to establish emission equivalence. But it has been suggested that this approach has serious shortcomings: damages or abatement costs are not considered and the choice of time horizon for calculating cumulative radiative force is critical, but arbitrary. Here we describe an alternative framework for determining emission equivalence between radiatively active gases that addresses these weaknesses. We focus on limiting temperature change and rate of temperature change, but our framework is also applicable to other objectives. For a proposed ceiling, we calculate how much one should be willing to pay for emitting an additional unit of each gas. The relative prices then determine the trade-off between gases at each point in time, taking into account economical as well as physical considerations. Our analysis shows that the relative prices are sensitive to the lifetime of the gases, the choice of target and the proximity of the target, making short-lived gases more expensive to emit as we approach the prescribed ceiling.
- Climate Change and Its Consequences
Environment (Washington DC) [Environment (Wash. DC)], vol. 43, no. 2, pp. 28-35, Mar 2001
The Earth's climate is changing, in large part because of the activities of humankind. The simplest measure of this change is the average temperature of the Earth's surface, which has risen approximately 0.7 degree Celsius over the past century, with most of the increase occurring in the past two decades. In other words, the Earth is undergoing global warming. The simplest predictor of this climate change is the steady growth of the amount of carbon dioxide (CO sub(2)) in the atmosphere. The concentration of CO sub(2), the most important greenhouse gas, has increased by more than 16 percent in the past 40 years and by more than 30 percent since the beginning of the industrial revolution 200 years ago. Although there are several consequences of climate change other than this increase in global average temperature, the most significant fact as we face the future is that scientists have, at best, an imperfect understanding of the global climate system. The possibility exists for noticeable deterioration of the climate in the United States even on a decadal time scale. Furthermore, unless the drivers of climate change are successfully addressed and controlled, no future stabilization point can be identified against the otherwise inexorable warming of the globe. As CO sub(2) continues to accumulate, doubling and then tripling in concentration, the expected warming will continue to increase. The further this proceeds, the greater the possibility that new chemical or physical processes will be triggered that release still more greenhouse gases. Many of the time scales for these processes, both human and geophysical, are decades to centuries in length, and major efforts must be begun before any irreversible processes begin.
- The Present, Past, and Future Contributions to Global Warming of CO sub(2) Emissions from Fuels
Rosa, LP; Ribeiro, SK
Climatic Change [Clim. Change], vol. 48, no. 2-3, pp. 289-307, Feb 2001
The objective of this paper is to emphasize the responsibility of developed countries to implement the Climate Convention, as well as the role of developing countries in CO sub(2) emissions control while sustaining their rights to increase energy consumption per capita during the development process. It is shown that the growth in CO sub(2) emissions from fossil fuel consumption in North America, excluding Mexico, from 1990 to 1996 was 3.7 times higher than that of Latin America in absolute terms. The cumulative contribution to global warming, expressed as the mass of the gas multiplied by time (GtCy), can be calculated as the integration of the atmospheric concentration of the emitted gas along time, with a weight function in the integrand to simulate the climate response. To simulate climate response, we used the superposition of exponential decay functions with different decay constants. The historical contributions of the OECD countries, the Eastern European countries and the ex-Soviet Union, and from all developing countries are considered. The future contributions are computed in three scenarios. All of them show that emissions from Non-Annex I countries will become higher than those of Annex I countries soon after 2010, while the curves of atmospheric concentration will cross one another later, not much before 2050, and the respective contributions to global temperature increase will cross about 2090.
- Climate change: The causes of 20th century warming
Zwiers, FW; Weaver, AJ
Science (Washington) [Science (Wash.)], vol. 290, no. 5499, pp. 2081-2083, 15 Dec 2000
Since 1860, global mean surface air temperatures have increased by 0.6 plus or minus 0.2 degree C, but this warming has not been continuous. Most of the warming has occurred during two distinct periods, from 1910 to 1945 and since 1976, with a very gradual cooling during the interventing period. Global warming critics have been quick to point out that the warming in the early 20th century occurred before the buildup of atmospheric greenhouse gases and have also noted that most model simulations of 20th century climate have failed to capture this feature. Recent studies have suggested that natural factors such as solar variability and lack of volcanic activity may have been important factors in the early warming.
- External control of 20th Century temperature by natural and anthropogenic forcings
Stott, PA; Tett, SFB; Jones, GS; Allen, MR; Mitchell, JFB; Jenkins, GJ
Science (Washington) [Science (Wash.)], vol. 290, no. 5499, pp. 2133-2137, 15 Dec 2000
A comparison of observations with simulations of a coupled ocean-atmosphere general circulation model shows that both natural and anthropogenic factors have contributed significantly to 20th century temperature changes. The model successfully simulates global mean and large-scale land temperature variations, indicating that the climate response on these scales is strongly influenced by external factors. More than 80% of observed multidecadal-scale global mean temperature variations and more than 60% of 10- to 50-year land temperature variations are due to changes in external forcings. Anthropogenic global warming under a standard emissions scenario is predicted to continue at a rate similar to that observed in recent decades.
- Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model
Cox, PM; Betts, RA; Jones, CD; Spall, SA; Totterdell, IJ
Nature, vol. 408, no. 6809, pp. 184-187, 9 Nov 2000
The continued increase in the atmospheric concentrations of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being observed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO sub(2) concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a "business as usual" scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C/yr is balanced by the terrestrial carbon source, and atmospheric CO sub(2) concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.
- Anthropogenic forcing and decadal climate variability in sensitivity experiments of twentieth- and twenty-first-century climate
Meehl, Gerald A; Washington, Warren M; Arblaster, Julie M; Bettge, Thomas W; Strand, Warren GJr
Journal of Climate [J Clim], vol. 13, no. 21, pp. 3728-3744, Nov 2000
A methodology is formulated to evaluate the possible changes in decadal-timescale (10-20-yr period) surface temperature variability and associated low-frequency fluctuations of anthropogenic forcing and changes in climate base state due to the forcing in simulations of twentieth- and twenty-first-century climate in a global coupled climate model without flux adjustment. The two climate change experiments both start in the year 1900. The first uses greenhouse gas radiative forcing (represented by equivalent CO sub(2)) observed during the twentieth century, and extends greenhouse gas forcing to the year 2035 by increasing CO sub(2) 1% yr super(-1) compound after 1990 (CO sub(2)-only experiment). The second includes the same greenhouse gas forcing as the first, but adds the effects of time-varying geographic distributions of monthly sulfate aerosol radiative forcing represented by a change in surface albedo (CO sub(2) + sulfates experiment). The climate change experiments are compared with a 135-yr control experiment with no change in external forcing. Climate system responses in the CO sub(2)-only and CO sub(2) + sulfates experiments in this particular model are marked not only by greater warming at high latitudes in the winter hemisphere, but also by a global El Nino-like pattern in surface temperature, precipitation, and sea level pressure. This pattern is characterized by a relatively greater increase of SST in the central and eastern equatorial Pacific in comparison with the west, a shift of precipitation maxima from the western Pacific to the central Pacific, mostly decreases of Asian-Australian monsoon strength, lower pressure over the eastern tropical Pacific, deeper midlatitude troughs in the North and South Pacific, and higher pressure over Australasia. Time series analysis of globally averaged temperature and an EOF analysis of surface temperature are consistent with previous results in that enhanced low-frequency variability with periods greater than around 20 yr is introduced into the model coupled climate system with a comparable timescale to the forcing. To examine the possible effects of the associated changes in base state on decadal timescale variability (10-20-yr periods), the surface temperature time series are filtered to retain only variability on that timescale.
- Quantifying the uncertainty in forecasts of anthropogenic climate change
Allen, MR; Stott, PA; Mitchell, JFB; Schnur, R; Delworth, TL
Nature, vol. 407, no. 6804, pp. 617-620, 5 Oct 2000
Forecasts of climate change are inevitably uncertain. It is therefore essential to quantify the risk of significant departures from the predicted response to a given emission scenario. Previous analyses of this risk have been based either on expert opinion, perturbation analysis of simplified climate models or the comparison of predictions from general circulation models. Recent observed changes that appear to be attributable to human influence provide a powerful constrain on the uncertainties in multi-decadal forecasts. Here we asess the range of warming rates over the coming 50 years that are consistent with the observed near-surface temperature record as well as with the overall patterns of response predicted by several general circulation models. We expect global mean temperatures in the decade 2036-46 to be 1-2.5 K warmer than in pre-industrial times under a "business as usual" emission scenario. This range is relatively robust to errors in the models' climate sensitivity, rate of oceanic heat uptake or global response to sulphate aerosols as long as these errors are persistent over time. Substantial changes in the current balance of greenhouse warming and sulphate aerosol cooling would, however, increase the uncertainty. Unlike 50-year warming rates, the final equilibrium warming after the atmospheric composition stabilizes remains very uncertain, despite the evidence provided by the emerging signal.
- Global Warming and Terrestrial Ecosystems: A Conceptual Framework for Analysis
Shaver, GR; Canadell, J; Chapin, FS III; Gurevitch, J; Harte, J; Henry, G; Ineson, P; Jonasson, S; Melillo, J; Pitelka, L; Rustad, L
Bioscience, vol. 50, no. 10, pp. 871-882, Oct 2000
Ecosystem responses to global warming will be complex and varied. Ecosystem warming experiments hold great potential for providing insights on ways terrestrial ecosystems will respond to upcoming decades of climate change. Documentation of initial conditions provides the context for understanding and predicting ecosystem responses.
- Causes of climate change over the past 1000 years
Science (Washington) [Science (Wash.)], vol. 289, no. 5477, pp. 270-277, 14 Jul 2000
Recent reconstructions of Northern Hemisphere temperatures and climate forcing over the past 1000 years allow the warming of the 20th century to be placed within a historical context and various mechanisms of climate change to be tested. Comparisons of observations with simulations from an energy balance climate model indicate that as much as 41 to 64% of preanthropogenic (pre-1850) decadal-scale temperature variations was due to changes in solar irradiance and volcanism. Removal of the forced response from reconstructed temperature time series yields residuals that show similar variability to those of control runs of coupled models, thereby lending support to the models' value as estimates of low-frequency variability in the climate system. Removal of all forcing except greenhouse gases from the similar to 1000-year time series results in a residual with a very large late-20th-century warming that closely agrees with the response predicted from greenhouse gas forcing. The combination of a unique level of temperature increase in the late 20th century and improved constraints on the role of natural variability provides further evidence that the greenhouse effect has already established itself above the level of natural variability in the climate system. A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial.
- Geoengineering Earth's radiation balance to mitigate CO sub(2)-induced climate change
Govindasamy, Bala; Caldeira, Ken
Geophysical Research Letters [Geophys Res Lett], vol. 27, no. 14, pp. 2141-2144, Jul 2000
To counteract anthropogenic climate change, several schemes have been proposed to diminish solar radiation incident on Earth's surface. These geoengineering schemes could reverse global annual mean warming; however, it is unclear to what extent they would mitigate regional and seasonal climate change, because radiative forcing from greenhouse gases such as CO sub(2) differs from that of sunlight. No previous study has directly addressed this issue. In the NCAR CCM3 atmospheric general circulation model, we reduced the solar luminosity to balance the increased radiative forcing from doubling atmospheric CO sub(2). Our results indicate that geoengineering schemes could markedly diminish regional and seasonal climate change from increased atmospheric CO sub(2), despite differences in radiative forcing patterns. Nevertheless, geoengineering schemes could prove environmentally risky.
- Response of the NCAR climate system model to increased CO sub(2) and the role of physical processes
Meehl, Gerald A; Collins, William D; Boville, Byron A; Kiehl, Jeffrey T; Wigley, TML; Arblaster, Julie M
Journal of Climate [J Clim], vol. 13, no. 11, pp. 1879-1898, Jun 2000
The global warming resulting from increased CO sub(2) is addressed in the context of two regional processes that contribute to climate change in coupled climate models, the 'El Nino-like' response (slackening of the equatorial Pacific SST gradient) and sea-ice response at high latitudes. The National Center for Atmospheric Research (NCAR) Climate System Model (CSM) response is compared with results from a coupled model that produces comparatively greater global warming, the NCAR U.S. Department of Energy (DOE) global coupled model. In an experiment where atmospheric CO sub(2) is increased 1% yr super(-1) compound, globally averaged surface air temperature increase near the time of CO sub(2) doubling for the CSM is 1.43 degree C (3.50 degree C for the DOE model). Analysis of a simple coupled model shows the CSM equilibrium sensitivity to doubled CO sub(2) is comparable to that from the slab ocean version (about 2.1 degree C). One process that contributes to global warming (estimated to be about 5% in one slab ocean model), as well as to significant Pacific region climate effects, is the El Nino-like response. It is a notable feature in the DOE model and some other global coupled models but does not occur in the CSM. The authors show that cloud responses are a major determining factor. With increased CO sub(2), there are negative net cloud-forcing differences in the western equatorial Pacific in the CSM and DOE models, but large positive differences in the DOE model and negative differences in the CSM in the eastern equatorial Pacific. This produces asymmetric cloud radiative forcing contributing to an El Nino-like response in the DOE model and not in the CSM. To remove the amplifying effects of ocean dynamics and to identify possible parameter-dependent processes that could contribute to such cloud forcing changes, the authors analyze slab ocean versions of the coupled models in comparison with a slab ocean configuration of the atmospheric model in the CSM [Community Climate Model Version 3 (CCM3)] that includes prognostic cloud liquid water. The latter shows a change in sign (from negative to positive) of the net cloud forcing in the eastern equatorial Pacific with doubled CO sub(2), similar to the DOE model, in comparison with the CCM3 version with diagnostic cloud liquid water. Atmospheric Model Intercomparison Project (prescribed SST) experiments show that all three atmospheric models (DOE, CCM3 with diagnostic cloud liquid water, and CCM3 with prognostic cloud liquid water) perform poorly relative to observations in terms of cloud radiative forcing, through CCM3 with prognostic cloud liquid water is slightly superior to the others.
- A transient climate change simulation with greenhouse gas and aerosol forcing: projected climate to the twenty-first century
Boer, GJ; Flato, G; Ramsden, D
Climate Dynamics [Clim. Dyn.], vol. 16, no. 6, pp. 427-450, 6 Jun 2000
The potential climatic consequences of increasing atmospheric greenhouse gas (GHG) concentration and sulfate aerosol loading are investigated for the years 1900 to 2100 based on five simulations with the CCCma coupled climate model. The five simulations comprise a control experiment without change in GHG or aerosol amount, three independent simulations with increasing GHG and aerosol forcing, and a simulation with increasing GHG forcing only. Climate warming accelerates from the present with global mean temperatures simulated to increase by 1.7 degree C to the year 2050 and by a further 2.7 degree C by the year 2100. The warming is non-uniform as to hemisphere, season, and underlying surface. Changes in interannual variability of temperature show considerable structure and seasonal dependence. The effect of the comparatively localized negative radiative forcing associated with the aerosol is to retard and reduce the warming by about 0.9 degree C at 2050 and 1.2 degree C at 2100. Its primary effect on temperature is to counteract the global pattern of GHG-induced warming and only secondarily to affect local temperatures suggesting that the first order transient climate response of the system is determined by feedback processes and only secondarily by the local pattern of radiative forcing. The warming is accompanied by a more active hydrological cycle with increases in precipitation and evaporation rates that are delayed by comparison with temperature increases. There is an "El Nino-like shift in precipitation and an overall increase in the interannual variability of precipitation. The effect of the aerosol forcing is again primarily to delay and counteract the GHG-induced increase. Decreases in soil moisture are common but regionally dependent and interannual variability changes show considerable structure. Snow cover and sea-ice retreat. A PNA-like anomaly in mean sea-level pressure with an enhanced Aleutian low in northern winter is associated with the tropical shift in precipitation regime. The interannual variability of mean sea-level pressure generally decreases with largest decreases in the tropical Indian ocean region. Changes to the ocean thermal structure are associated with a spin-down of the Atlantic thermohaline circulation together with a decrease in its variability. The effect of aerosol forcing, although modest, differs from that for most other quantities in that it does not act primarily to counteract the GHG forcing effect. The barotropic stream function in the ocean exhibits modest change in the north Pacific but accelerating changes in much of the Southern Ocean and particularly in the north Atlantic where the gyre spins down in conjunction with the decrease in the thermohaline circulation. The results differ in non-trivial ways from earlier equilibrium 2 CO2 results with the CCCma model as a consequence of the coupling to a fully three-dimensional ocean model and the evolving nature of the forcing.
- Climate change: Potential impacts and interactions in wetlands of the United States
Burkett, V; Kusler, J
Journal of the American Water Resources Association [J. Am. Water Resour. Assoc.], vol. 36, no. 2, pp. 313-320, Apr 2000
Wetlands exist in a transition zone between aquatic and terrestrial environments which can be altered by subtle changes in hydrology. Twentieth century climate records show that the United States is generally experiencing a trend towards a wetter, warmer climate; some climate models suggest that this trend will continue and possibly intensify over the next 100 years. Wetlands that are most likely to be affected by these and other potential changes (e.g., sea-level rise) associated with atmospheric carbon enrichment include permafrost wetlands, coastal and estuarine wetlands, peatlands, alpine wetlands, and prairie pothole wetlands. Potential impacts range from changes in community structure to changes in ecological function, and from extirpation to enhancement. Wetlands (particularly boreal peatlands) play an important role in the global carbon cycle, generally sequestering carbon in the form of biomass, methane, dissolved organic material and organic sediment. Wetlands that are drained or partially dried can become a net source of methane and carbon dioxide to the atmosphere, serving as a positive biotic feedback to global warming. Policy options for minimizing the adverse impacts of climate change on wetland ecosystems include the reduction of current anthropogenic stresses, allowing for inland migration of coastal wetlands as sea-level rises, active management to preserve wetland hydrology, and a wide range of other management and restoration options.
- Simulation of early 20th century global warming
Delworth, TL; Knutson, TR
Science (Washington) [Science (Wash.)], vol. 287, no. 5461, pp. 2246-2250, 24 Mar 2000
The observed global warming of the past century occurred primarily in two distinct 20-year periods, from 1925 to 1944 and from 1978 to the present. Although the latter warming is often attributed to a human-induced increase of greenhouse gases, causes of the earlier warming are less clear because this period precedes the time of strongest increases in human-induced greenhouse gas (radiative) forcing. Results from a set of six integrations of a coupled ocean-atmosphere climate model suggest that the warming of the early 20th century could have resulted from a combination of human-induced radiative forcing and an unusually large realization of internal multidecadal variability of the coupled ocean-atmosphere system. This conclusion is dependent on the model's climate sensitivity, internal variability, and the specification of the time-varying human-induced radiative forcing.
- Simulated responses of potential vegetation to doubled-CO sub(2) climate change and feedbacks on near-surface temperature
Betts, RA; Cox, PM; Woodward, FI
Global Ecology and Biogeography [Global Ecol. Biogeogr.], vol. 9, no. 2, pp. 171-180, Mar 2000
Increases in the atmospheric concentration of carbon dioxide and associated changes in climate may exert large impacts on plant physiology and the density of vegetation cover. These may in turn provide feedbacks on climate through a modification of surface-atmosphere fluxes of energy and moisture. This paper uses asynchronously coupled models of global vegetation and climate to examine the responses of potential vegetation to different aspects of a doubled-CO sub(2) environmental change, and compares the feedbacks on near-surface temperature arising from physiological and structural components of the vegetation response. Stomatal conductance reduces in response to the higher CO sub(2) concentration, but rising temperatures and a redistribution of precipitation also exert significant impacts on this property as well as leading to major changes in potential vegetation structure. Overall, physiological responses act to enhance the warming near the surface, but in many areas this is offset by increases in leaf area resulting from greater precipitation and higher temperatures. Interactions with seasonal snow cover result in a positive feedback on winter warming in the boreal forest regions.
- Record breaking global temperatures of 1997 and 1998: evidence for an increase in the rate of global warming?
Karl, Thomas R; Knight, Richard W; Baker, Bruce
Geophysical Research Letters [Geophys Res Lett], vol. 27, no. 5, pp. 719-722, 1 Mar 2000
During the time between May of 1997 and September of 1998, for sixteen consecutive months, each month broke the previous monthly all-time record high temperature. Using autoregressive intervention moving average (ARMA) models in a series of Monte Carlo experiments the probability of such an event was analyzed for various rates of temperature change. The string of record-breaking global temperatures could not be readily explained by the best fit linear increase of temperature since the late 1970's (2 degree C/Century), although the event was not implausible (probabilities slightly less than 5%). The 1997-98 event could signal yet another change point in the rate of global temperature increase, but the warming rate over the past few decades is already comparable to that projected during the 21st Century based on IPCC business as usual scenarios of anthropogenic climate change (Kattenberg et al., 1996).
- Global warming and the temperature of inland waters
Japanese Journal of Limnology [Jap. J. Limnol.], vol. 61, no. 1, pp. 24-34, Feb 2000
The effects of global warming on inland waters are reviewed and discussed in this paper. Latitudinal distributions of the water temperature and the lake circulation type are explained based on the annual mean and range of the equilibrium temperature. Long-term observations on lakes and rivers have clarified the warming trend in recent years. Although several simulations have already been made to predict the temperature field in the 21st century, these results are widely divergent because of the differences in General Circulation Models. It may be said that predictions of water temperature are not reliable at present. The other reason for instability in the predictions is the lack of accurate long-term data on water temperature. Since basic knowledge of the relationship between climate change and water temperature can be obtained from the long-term record, it is necessary to summarize the temperature record. Another way to determine the effect of climate on water temperature may be an investigation into particularly warm or cold years. A poor ice winter in Lake Suwa has also been discussed in relation to El Nino as an example of an anomalous climate event, the historical record on the ice cover in Lake Suwa was compared with the historical winter temperature estimated from an old diary at Tsu City, Mie Prefectures. It is pointed out that warm winter at Tsu and poor ice in Lake Suwa appeared in the same decades, and more than half of these warm events were associated with El Nino. Such exceptional climate events should be also taken into consideration in the prediction and monitoring of inland waters.
- Socioeconomic impacts of climate change on U.S. water supplies
Frederick, KD; Schwarz, GE
Journal of the American Water Resources Association [J. Am. Water Resour. Assoc.], vol. 35, no. 6, pp. 1563-1584, Dec 1999
A greenhouse warming would have major effects on water supplies and demands. A framework for examining the socioeconomic impacts associated with changes in the long-term availability of water is developed and applied to the hydrologic implications of the Canadian and British Hadley2 general circulation models (GCMs) for the 18 water resource regions in the conterminous United States. The climate projections of these two GCMs have very different implications for future water supplies and costs. The Canadian model suggests most of the nation would be much drier in the year 2030. Under the least-cost management scenario the drier climate could add nearly $105 billion to the estimated costs of balancing supplies and demands relative to the costs without climate change. Measures to protect instream flows and irrigation could result in significantly higher costs. In contrast, projections based on the Hadley model suggest water supplies would increase throughout much of the nation, reducing the costs of balancing water supplies with demands relative to the no-climate-change case.
- Costs, benefits and sustainability in decision-making, with special reference to global warming
International Journal of Sustainable Development [Int. J. Sustainable Dev.], vol. 3, no. 4, pp. 315-333, 2000
Environmental decision-making, like economic decision-making, often involves trade-offs. Decision-makers need techniques with which to compare the costs and benefits involved. For some environmental problems, such as global warming, there are insuperable difficulties to making operational what might seem the obvious technique, cost-benefit analysis. Broadening the decision-making framework, four models are presented - cost-oblivious, cost-effective, and cost-sensitive models and strict cost-benefit analysis - which give increasing weight to the role of cost in influencing the policy objective. The practical principles that can be derived from the emerging concept of environmental sustainability are shown to be able to play an important role in guiding environmental policy for all the models except for strict cost-benefit analysis. They can also be used to derive quantitative targets for environmental policy, and this is carried out for carbon emissions in relation to climate change. These principles may therefore be particularly useful for those issues for which, like global warming, the application of CBA is problematic.
- Water Resources Implications of Global Warming: A U.S. Regional Perspective
Lettenmaier, DP; Wood, AW; Palmer, RN; Wood, EF; Stakhiv, EZ
Climatic Change [Clim. Change], vol. 43, no. 3, pp. 537-579, Nov 1999
The implications of global warming for the performance of six U.S. water resource systems are evaluated. The six case study sites represent a range of geographic and hydrologic, as well as institutional and social settings. Large, multi-reservoir systems (Columbia River, Missouri River, Apalachicola-Chatahoochee-Flint (ACF) Rivers), small, one or two reservoir systems (Tacoma and Boston) and medium size systems (Savannah River) are represented. The studies inferred, using a chain of climate downscaling, hydrologic and water resources systems models, the sensitivity of six water resources systems to changes in precipitation, temperature and solar radiation. The climate change scenarios used in this study are based on results from transient climate change experiments performed with coupled ocean-atmosphere General Circulation Models (GCMs) for the 1995 Intergovernmental Panel on Climate Change (IPCC) assessment. Changes in precipitation are generally reflected in the annual total runoff volumes more than in the seasonal shape of the hydrographs. In the Savannah and ACF systems, where snow plays a minor hydrological role, changes in hydrological response are linked more directly to temperature and precipitation changes. Effects on system performance varied from system to system, from GCM to GCM, and for each system operating objective (such as hydropower production, municipal and industrial supply, flood control, recreation, navigation and instream flow protection). Effects were generally smaller for the transient scenarios than for the doubled CO sub(2) scenario. In terms of streamflow, one of the transient scenarios tended to have increases at most sites, while another tended to have decreases at most sites. The third showed no general consistency over the six sites. Generally, the water resource system performance effects were determined by the hydrologic changes and the amount of buffering provided by the system's storage capacity. The effects of demand growth and other plausible future operational considerations were evaluated as well. For most sites, the effects of these non-climatic effects on future system performance would about equal or exceed the effects of climate change over system planning horizons.
- Multi-gas assessment of the Kyoto Protocol
Reilly, J; Prinn, R; Harnisch, J; Fitzmaurice, J; Jacoby, H; Kicklighter, D; Melillo, J; Stone, P; Sokolov, A; Wang, C
Nature, vol. 401, no. 6753, pp. 549-555, 7 Oct 1999
The Kyoto Protocol allows reductions in emissions of several "greenhouse" gases to be credited against a CO sub(2)-equivalent emissions limit, calculated using "global warming potential" indices for each gas. Using an integrated global-systems model, it is shown that a multi-gas control strategy could greatly reduce the costs of fulfilling the Kyoto Protocol compared with a CO sub(2)-only strategy. Extending the Kyoto Protocol to 2100 without more severe emissions reductions shows little difference between the two strategies in climate and ecosystem effects. Under a more stringent emissions policy, the use of global warming potentials as applied in the Kyoto Protocol leads to considerably more mitigation of climate change for multi-gas strategies than for the--supposedly equivalent--CO sub(2)-only control, thus emphasizing the limits of global warming potentials as a tool for political decisions.
- Selection of appropriate greenhouse gas mitigation options
Global Environmental Change, Part A: Human and Policy Dimensions [Global Environ. Change Pt. A: Human Policy Dimensions], vol. 9, no. 3, pp. 203-210, Oct 1999
Greenhouse gas mitigation options help in reducing greenhouse gas emissions so as to avoid the adverse environmental impacts due to global warming/climate change. They have different characteristics when evaluated using different criteria. For example, some options may be very cost effective, while some may have an additional advantage of reducing local pollution. Hence, selection of these options, for consideration by a national government or by a funding agency, has to incorporate multiple criteria. In this paper, some important criteria relevant to the selection are discussed, and a multi-criteria methodology is suggested for making appropriate selection. The methodology, called the Analytic Hierarchy Process, is described using two illustrations.
- Addressing global warming and biodiversity through forest restoration and coastal wetlands creation
Science of the Total Environment [Sci. Total Environ.], vol. 240, no. 1-3, pp. 1-9, 18 Oct 1999
The Climate Challenge is a partnership between the Department of Energy and the electric utility industry to reduce, avoid, and sequester greenhouse gases. A portion of the initiative, the sequestration of greenhouse gases, is the focus of this presentation. Over 4 million acres of bottomland hardwood forests were cleared for agriculture in the Mississippi River Valley in the 1970s. Reestablishing these forests would improve depleted wildlife habitats, serve as wildlife corridors, increase biodiversity, and decrease soil erosion. Also, Louisiana is losing coastal wetlands at a rate of approximately 25 square miles/year. This coastal erosion is due to a number of factors and many efforts are currently underway to address the matter. One such effort is the use of material generated in the dredging of navigational canals; however, this material is low in nutrient value, making the regeneration of marsh grasses more difficult. In addition, bottomland hardwood forests and coastal wetland grasses are excellent `carbon sinks' because they take carbon dioxide out of the atmosphere and store it in living plant tissue. Entergy Services, Inc. is an electric utility with a service territory that comprises portions of both the Lower Mississippi River Valley and the Gulf of Mexico coastline. This provides an opportunity to positively address both habitat losses noted above while at the same time addressing global warming, forest fragmentation, and biodiversity. Entergy, through its affiliation with the UtiliTree Carbon Company, is participating in projects that will investigate the feasibility of using bottomland hardwood reforestation on cleared marginal farmlands now managed by the Louisiana Department of Wildlife and Fisheries and the US Fish and Wildlife Service. Entergy has also begun a research project with the Environmental Protection Agency and the state of Louisiana. The research is a compost demonstration project that will utilize wood waste generated through our tree-trimming program as a compost material that will be mixed with low nutrient dredge material to create new coastal wetlands. Taken together, Entergy's initiatives will be able to address global warming through carbon sequestration, restore fragmented forest habitats, reduce coastal erosion and improve the quality of a vital coastal aquatic nursery habitat. Efforts will be made to manage the created habitats for biodiversity. Pulling all these ideas together creates an effect in which the whole is greater than the sum of the parts. In such a synergy of ideas, there are no losers and the winners are both industry participants and the environment.
- Long-Term Global Warming Scenarios Computed with an Efficient Coupled Climate Model
Rahmstorf, S; Ganopolski, A
Climatic Change [Clim. Change], vol. 43, no. 2, pp. 353-367, Oct 1999
We present global warming scenarios computed with an intermediate-complexity atmosphere-ocean-sea ice model which has been extensively validated for a range of past climates (e.g., the Last Glacial Maximum). Our simulations extend to the year 3000, beyond the expected peak of CO sub(2) concentrations. The thermohaline ocean circulation declines strongly in all our scenarios over the next 50 years due to a thermal effect. Changes in the hydrological cycle determine whether the circulation recovers or collapses in the long run. Both outcomes are possible within present uncertainty limits. In case of a collapse, a substantial long-lasting cooling over the North Atlantic and a drying of Europe is simulated.
- Changes in Heat Index Associated with CO2-Induced Global Warming
Delworth, TL; Mahlman, JD; Knutson, TR
Climatic Change [Clim. Change], vol. 43, no. 2, pp. 369-386, Oct 1999
Changes in Heat Index (a combined measure of temperature and humidity) associated with global warming are evaluated based on the output from four extended integrations of the GFDL coupled ocean-atmosphere climate model. The four integrations are: a control with constant levels of atmospheric carbon dioxide (CO sub(2)), a second integration in which an estimate of the combined radiative forcing of greenhouse gases and sulfate aerosols over the period 1765-2065 is used to force the model, and a third (fourth) integration in which atmospheric CO sub(2)$ increases at the rate of 1% per year to double (quadruple) its initial value, and is held constant thereafter. While the spatial patterns of the changes in Heat Index are largely determined by the changes in surface air temperature, increases in atmospheric moisture can substantially amplify the changes in Heat Index over regions which are warm and humid in the Control integration. The regions most prone to this effect include humid regions of the Tropics and summer hemisphere extra-tropics, including the southeastern United States, India, southeast Asia and northern Australia.
- Future African Water Resources: Interactions between Soil Degradation and Global Warming
Climatic Change [Clim. Change], vol. 42, no. 3, pp. 561-596, Jul 1999
This study uses a well-established water balance methodology to evaluate the relative impact of global warming and soil degradation due to desertification on future African water resources. Using a baseline climatology, a GCM global warming scenario, a newly derived soil water-holding capacity data set, and a worldwide survey of soil degradation between 1950 and 1980, four climate and soil degradation scenarios are created to simulate the potential impact of global warming and soil degradation on African water resources for the 2010-2039 time period. Results indicate that, on a continental scale, the impact of global warming will be significantly greater than the impact of soil degradation. However, when only considering the locations where desertification is an issue (wet and dry climate regions), the potential effects of these two different human impacts on local water resources can be expected to be on the same order of magnitude. Drying associated with global warming is primarily the result of increased water demand (potential evapotranspiration) across the entire continent. While there are small increases in precipitation under global warming conditions, they are inadequate to meet the increased water demand. Soil degradation is most severe in highly populated, wet and dry climate regions and results in decreased water-holding capacities in these locations. This results in increased water surplus conditions during wet seasons when the soil's ability to absorb precipitation is reduced. At the same time, water deficits in these locations increase because of reduced soil water availability in the dry seasons. The net result of the combined scenarios is an intensification and extension of drought conditions during dry seasons.
- Risk Perceptions, General Environmental Beliefs, and Willingness to Address Climate Change
O'Connor, RE; Bord, RJ; Fisher, A
Risk Analysis [Risk Anal.], vol. 19, no. 3, pp. 461-472, Jun 1999
The research reported here examines the relationship between risk perceptions and willingness to address climate change. The data are a national sample of 1225 mail surveys that include measures of risk perceptions and knowledge tied to climate change, support for voluntary and government actions to address the problem, general environmental beliefs, and demographic variables. Risk perceptions matter in predicting behavioral intensions. Risk perceptions are not a surrogate for general environmental beliefs, but have their own power to account for behavioral intentions. There are four secondary conclusions. First, behavioral intentions regarding climate change are complex and intriguing. People are neither "nonbelievers" who will take no initiatives themselves and oppose all government efforts, nor are they "believers" who promise both to make personal efforts and to vote for every government proposal that promises to address climate change. Second, there are separate demographic sources for voluntary actions compared with voting intentions. Third, recognizing the causes of global warming is a powerful predictor of behavioral intentions independent from believing that climate change will happen and have bad consequences. Finally, the success of the risk perception variables to account for behavioral intentions should encourage greater attention to risk perceptions as independent variables. Risk perceptions and knowledge, however, share the stage with general environmental beliefs and demographic characteristics. Although related, risk perceptions, knowledge, and general environmental beliefs are somewhat independent predictors of behavioral intentions.
- Global warming and marine carbon cycle feedbacks on future atmospheric CO sub(2)
Joos, F; Plattner, G-K; Stocker, TF; Marchal, O; Schmittner, A
Science (Washington) [Science (Wash.)], vol. 284, no. 5413, pp. 464-467, 16 Apr 1999
A low-order physical-biogeochemical climate model was used to project atmospheric carbon dioxide and global warming for scenarios developed by the intergovernmental Panel on Climate Change. The North Atlantic thermohaline circulation weakens in all global warming simulations and collapses at high levels of carbon dioxide. Projected changes in the marine carbon cycle have a modest impact on atmospheric carbon dioxide. Compared with the control, atmospheric carbon dioxide increased by 4 percent at year 2100 and 20 percent at year 2500. The reduction in ocean carbon uptake can be mainly explained by sea surface warming. The projected changes of the marine biological cycle compensate the reduction in downward mixing of anthropogenic carbon, except when the North Atlantic thermohaline circulation collapses.
- Means to reduce CO sub(2) - Emissions in the Chinese electricity system, with special consideration to wind energy
RENEWABLE ENERGY: ENERGY EFFICIENCY, POLICY AND THE ENVIRONMENT. WORLD RENEWABLE ENERGY CONGRESS V, Apr 1999, pp. 899-903, Renewable Energy [Renewable Energy ], vol. 16, no. 1-4
It is believed that the "greenhouse effect" will lead to a worldwide climate change with unpredictable but probably dangerous climate changes for human beings in most parts of the world. The "greenhouse effect" is a result of a rising atmospheric concentration of carbon dioxide emmissions and other "greenhouse gases". Most scientists around the world recommend that these emissions should be reduced significantly if mankind intends to stop the climatic changes. However, China argues that countries with high per head CO sub(2)-emissions such as the USA, the EU and the former USSR should reduce their emissions first. Furthermore, these countries have an obligation to reduce their CO sub(2)-emissions because they have been responsible for a high proportion of the emissions over the last 40 years. On the other hand, China is already responsible for 11,2 percent of worldwide CO sub(2)-emissions, which places China in third place behind the USA and the former USSR. The growing economy in China will lead to a rapid increase in CO sub(2)-emissions in the future, which will have important implications for any international effort to cut CO sub(2)-emissions to reduce the risk of global warming. As electricity production is responsible for about 23% (or 575 million tons in 1992) of Chinese CO sub(2)-emissions, this sector is of particular interest. This paper analyses the technical possibilities which exist to avoid a large increase in CO sub(2)-emissions produced by electricity generation in China.
- Direct Groundwater Fluxes Under 2 x CO sub(2) Global Warming Scenario
Water Resources [Water Resour.]; Vodnye Resursy , vol. 26, no. 2, pp. 126-131; vol. 26, no. 2, pp. 149-153, Apr 1999
Changes in global streamflow, direct groundwater flux, and direct salt discharge have been estimated under the 2 x CO sub(2) global-warming scenario relative to present-day mean values. Assuming a global mean precipitation increase of 10% (9350 km super(3)/yr) and a rise in net available energy equal to 4 W/m super(2), the runoff coefficient in a 2 x CO sub(2) climate would rise by 5% over its current mean global value. The associated predicted changes in global streamflow, direct groundwater flux, and direct salt discharge to the oceans are estimated at 6370 km super(3)/yr, 403 km super(3)/yr, and 218 x 10 super(6) t/yr, respectively. A concomitant global mass/energy balance in the oceanic and atmospheric reservoirs requires an increase in mean continental evapotranspiration on the order of 4180 km super(3)/yr, a gain in mean oceanic precipitation of 9240 km super(3)/yr, and an increase in mean oceanic evaporation of 16,010 km super(3)/yr. The sensitivities of predictions were evaluated with respect to the streamflow coefficient k sub(s), the direct groundwater coefficient k sub(g), and the Bowen ratio. Calculated Bowen ratio sensitivities were all equal to 0.28, implying that, say, a 10% rise in the Bowen ratio would produce a 2.8% rise in global streamflow, direct groundwater flux, and direct salt discharge. Model prediction sensitivities to k sub(s) and k sub(g) were equal to -1 in all cases, implying that a 10% increase in either k sub(s) or k sub(g) results in a 10% decrease in global streamflow, direct groundwater flux, and direct salt discharge.
- Modeling snow cover and runoff response to global warming for varying hydrological years
Rango, A; Martinec, J
World Resource Review [World Resour. Rev.], vol. 11, no. 1, pp. 76-91, Mar 1999
The effect of future global warming on the seasonal snow cover and runoff is evaluated in the Rio Grande basin at Del Norte, Colorado for average (1976), low (1977), and high (1979) runoff years. Precipitation data are extrapolated to the respective elevations of the basin by taking into account the snow accumulation obtained from snow cover mapping by satellites. Snow covered areas are used as one of the input variables for the Snowmelt Runoff Model. In order to derive the climate-affected snow covered areas of the future, the decrease of the areal snow water equivalent on 1 April is computed and used to derive new snow cover depletion curves indicative of the accelerated snowmelt in the warmer climate. Day-by-day runoff computations using present temperatures and temperatures increased by +4 degree C reveal a short-term and seasonal redistribution of runoff which differs according to the character of the selected hydrological years. Winter runoff approximately doubles in 1976 (+ 107%), considerably increases in 1979 (+ 60%), and slightly rises in 1977 (+ 22%). The summer runoff consequently declines in all years, but the seasonal runoff peaks are shifted to earlier in the spring as a result of an earlier beginning of the snowmelt season in the warmer climate.
- Climate change, coral bleaching and the future of the world's coral reefs
Marine & Freshwater Research [Mar. Freshwat. Res.], vol. 50, no. 8, pp. 839-66, 1999
Sea temperatures in many tropical regions have increased by almost 1 degree C over the past 100 years, and are currently increasing at similar to 1-2 degree C per century. Coral bleaching occurs when the thermal tolerance of corals and their photosynthetic symbionts (zooxanthellae) is exceeded. Mass coral bleaching has occurred in association with episodes of elevated sea temperatures over the past 20 years and involves the loss of the zooxanthellae following chronic photoinhibition. Mass bleaching has resulted in significant losses of live coral in many parts of the world. This paper considers the biochemical, physiological and ecological perspectives of coral bleaching. It also uses the outputs of four runs from three models of global climate change which simulate changes in sea temperature and hence how the frequency and intensity of bleaching events will change over the next 100 years. The results suggest that the thermal tolerances of reef-building corals are likely to be exceeded every year within the next few decades. Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years. Most information suggests that the capacity for acclimation by corals has already been exceeded, and that adaptation will be too slow to avert a decline in the quality of the world's reefs. The rapidity of the changes that are predicted indicates a major problem for tropical marine ecosystems and suggests that unrestrained warming cannot occur without the loss and degradation of coral reefs on a global scale.
- Global change: A piece in the CO~2 jigsaw
Bakker, D; Watson, A
Nature -LONDON-; ISSU 6830; pp. 765; 12 Apr 2001
A study of the year-to-year variation in net CO@d2 uptake by the oceans helps in assessing the mechanisms of global climate change. The burning of fossil fuels releases carbon dioxide into the atmosphere, where its increasing concentration promotes global warming. Some of this CO@d2 is absorbed by terrestrial systems and the oceans. But the location and year-to-year variation of these "sinks" are badly quantified. Writing in Geophysical Research Letters, Loukos et al. describe an innovative approach to estimating the exchange of CO@d2 between the air and the sea for the equatorial Pacific Ocean over a ten-year period. One remarkable finding, narrowing the gap between other studies, is that there is little variation from year to year in such CO@d2 air-sea transfer in the tropical oceans.
- Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model
Cox, P.M.; Betts, R.A.; Jones, C.D.; Spall, S.A.; Totterdell, I.J.
Nature, vol. 408, no. 6809, pp. 184-187, 9 Nov 2000
The continued increase in the atmospheric concentrations of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. About half of the current emissions are being observed by the ocean and by land ecosystems, but this absorption is sensitive to climate as well as to atmospheric carbon dioxide concentrations, creating a feedback loop. General circulation models have generally excluded the feedback between climate and the biosphere, using static vegetation distributions and CO@d2 concentrations from simple carbon-cycle models that do not include climate change. Here we present results from a fully coupled, three-dimensional carbon-climate model, indicating that carbon-cycle feedbacks could significantly accelerate climate change over the twenty-first century. We find that under a "business as usual" scenario, the terrestrial biosphere acts as an overall carbon sink until about 2050, but turns into a source thereafter. By 2100, the ocean uptake rate of 5 Gt C/yr is balanced by the terrestrial carbon source, and atmospheric CO@d2 concentrations are 250 p.p.m.v. higher in our fully coupled simulation than in uncoupled carbon models, resulting in a global-mean warming of 5.5 K, as compared to 4 K without the carbon-cycle feedback.
- Climate change and sustainable water resources: placing the threat of global warming in perspective
Hydrological Sciences Journal [Hydrol Sci J], vol. 44, no. 4, pp. 541-558, 1999
Predicted climate change over the coming decades is likely to add measurable stress to water resources in many regions of the world, including some areas that are currently well endowed. The stresses are likely to involve changes in the frequency of extreme events as well as gradual changes in mean annual net resources. The paper analyses these predictions. It also attempts to place them in context, first, comparing their impact with other major barriers to sustainability, such as increasing demand, wastage, poor water resources assessment and international conflict, and, secondly, considering the limitations of current predictive techniques.
- Climate change impacts on ecosystems and the terrestrial carbon sink: a new assessment
White, A; Cannell, MGR; Friend, AD
Global Environmental Change, Part A: Human and Policy Dimensions [Global Environ. Change Pt. A: Human Policy Dimensions], vol. 9, Suppl., pp. S21-S30, 1999
Climate output from the UK Hadley Centre's HadCM2 and HadCM3 experiments for the period 1860 to 2100, with IS92a greenhouse gas forcing, together with predicted patterns of N deposition and increasing CO sub(2), were input (offline) to the dynamic vegetation model, Hybrid v4.1 (Friend et al., 1997; Friend and White, 1999). This model represents biogeochemical, biophysical and biogeographical processes, coupling the carbon, nitrogen and water cycles on a sub-daily timestep, simulating potential vegetation and transient changes in annual growth and competition between eight generalized plant types in response to climate. Global vegetation carbon was predicted to rise from about 600 to 800 PgC (or to 650 PgC for HadCM3) while the soil carbon pool of about 1100 PgC decreased by about 8%. By the 2080s, climate change caused a partial loss of Amazonian rainforest, C sub(4) grasslands and temperate forest in areas of southern Europe and eastern USA, but an expansion in the boreal forest area. These changes were accompanied by a decrease in net primary productivity (NPP) of vegetation in many tropical areas, southern Europe and eastern USA (in response to warming and a decrease in rainfall), but an increase in NPP of boreal forests. Global NPP increased from 45 to 50 PgC y super(-1) in the 1990s to about 65 PgC y super(-1) in the 2080s (about 58 PgC y super(-1) for HadCM3). Global net ecosystem productivity (NEP) increased from about 1.3 PgC y super(-1) in the 1990s to about 3.6 PgC y super(-1) in the 2030s and then declined to zero by 2100 owing to a loss of carbon from declining forests in the tropics and at warm temperate latitudes -- despite strengthening of the carbon sink at northern high latitudes. HadCM3 gave a more erratic temporal evolution of NEP than HadCM2, with a dramatic collapse in NEP in the 2050s.
- The economics of "when" flexibility in the design of greenhouse gas abatement policies
Toman, MA; Morgenstern, RD; Anderson, J
Annual Review of Energy and the Environment [Annu. Rev. Energy Environ.], vol. 24, pp. 431-460, 1999
This paper focuses on the desirability, from an economic perspective, of setting fixed and relatively short-term targets and timetables, such as those contained in the Kyoto Protocol, as a means of achieving longer-term climate change mitigation goals. The paper argues that whatever long-term policy goals are adopted, greater flexibility lowers implementation costs. Lower implementation costs, in turn, increases the likelihood that the policies will actually be followed and the goals achieved. Importantly, the Kyoto Protocol incorporates key elements of both "what" and "where" flexibility. That is, the "Kyoto basket" includes all six of the major greenhouse gases plus sinks, and the Protocol incorporates several mechanisms that allow emission reductions to take place at the least-cost geographic location, regardless of nation-state boundaries. The Protocol also provides substantial "how" flexibility in the sense that countries can use a variety of means to achieve domestic policy goals. However, the Protocol does not allow emission reductions to take place at a point in time when they can be achieved at lowest cost as long as they are consistent with the long-term environmental goals ("when" flexibility). Additionally, it does not allow the use of efficient price-based policy instruments to define targets and, thereby, balance environmental goals and compliance costs (which could be thought of as a broader version of "when" flexibility). Instead, the Protocol relies exclusively on strict, short term quantity targets. The relative inflexibility of the Protocol with respect to the timing of reductions and definitions of the targets may derive, in part, from a misplaced analogy between the global warming issue and the highly successful effort to phase out CFCs under the Montreal Protocol. The lack of when flexibility may be a key barrier to achieving the broader goals of the Kyoto Protocol, particularly if where flexibility is constrained in the implementation process
- International cooperation and the adoption of environmentally responsible technologies
International Journal of Environment and Pollution [Int. J. Environ. Pollut.], vol. 12, no. 1, pp. 10-13, 1999
Adoption of technologies for energy production with improved environmental performance is essential for supporting world economic growth and managing the global warming and climate change issues. International cooperation is critical to ensure the environmental and energy security of world economies on a global basis. For example, the USA has acquired a great deal of useful experience in clean coal technology, which has been demonstrated with major utilities in commercial operations. The adoption and installation of clean coal technology should be given high priority worldwide. The continuous exchange of information and technology between developed and developing economies relating to current and fut4f great importance. Developed economies that possess environmentally responsive technologies and financial resources should work closely with developing economies to facilitate technology transfer and trade of technologies. Cooperation between economies can result in lowering the cost of deploying clean coal technologies directed toward the clean production of energy. This paper discusses a bilateral approach, i.e. the US/China Center for Energy and Environment, to facilitate the mitigation of emissions and promote the clean use of coal to satisfy growing energy demand in developing economies.
- Biotic feedbacks in the warming of the earth
Woodwell, GM; Mackenzie, FT; Houghton, RA; Apps, M; Gorham, E; Davidson, E
Climatic Change [Clim. Change], vol. 40, no. 3-4, pp. 495-518, Dec 1998
A positive correlation exists between temperature and atmospheric concentrations of carbon dioxide and methane over the last 220,000 years of glacial history, including two glacial and three interglacial periods. A similar correlation exists for the Little Ice Age and for contemporary data. Although the dominant processes responsible may be different over the three time periods, a warming trend, once established, appears to be consistently reinforced through the further accumulation of heat-trapping gases in the atmosphere; a cooling trend is reinforced by a reduction in the release of heat-trapping gases. Over relatively short periods of years to decades, the correspondence between temperature and greenhouse gas concentrations may be due largely to changes in the metabolism of terrestrial ecosystems, whose respiration, including microbial respiration in soils, responds more sensitively, and with a greater total effect, to changes in temperature than does gross photosynthesis. Despite the importance of positive feedbacks and the recent rise in surface temperatures, terrestrial ecosystems seem to have been accumulating carbon over the last decades. The mechanisms responsible are thought to include increased nitrogen mobilization as a result of human activities, and two negative feedbacks: CO sub(2) fertilization and the warming of the earth, itself, which is thought to lead to an accumulation of carbon on land through increased mineralization of nutrients and, as a result, increased plant growth. The relative importance of these mechanisms is unknown, but collectively they appear to have been more important over the last century than a positive feedback through warming-enhanced respiration. The recent rate of increase in temperature, however, leads to concern that we are entering a new phase in climate, one in which the enhanced greenhouse effect is emerging as the dominant influence on the temperature of the earth. Two observations support this concern. One is the negative correlation between temperature and global uptake of carbon by terrestrial ecosystems. The second is the positive correlation between temperature and the heat-trapping gas content of the atmosphere. While CO sub(2) fertilization or nitrogen mobilization (either directly or through a warming-enhanced mineralization) may partially counter the effects of a warming-enhanced respiration, the effect of temperature on the metabolism of terrestrial ecosystems suggests that these processes will not entirely compensate for emissions of carbon resulting directly from industrial and land-use practices and indirectly from the warming itself. The magnitude of the positive feedback, releasing additional CO sub(2), CH sub(4), and N sub(2)O, is potentially large enough to affect the rate of warming significantly.
- Global methane emission from wetlands and its sensitivity to climate change
Cao, Mingkui; Gregson, Keith; Marshall, Stewart
Atmospheric Environment [ATMOS ENVIRON], vol. 32, no. 19, pp. 3293-3299, Oct 1998
The concentration of atmospheric methane (CH sub(4)) exerts a strong influence on atmospheric chemistry and the global climate. Natural and cultivated wetlands (rice paddies) are important sources of CH sub(4), and the extent and strength of these sources may increase as a result of global warming and extension of rice production. Emission of methane from wetlands is an ecosystem process, closely coupled to local climatic and soil environments which influence complex processes of plant growth, soil organic matter decomposition, methanogenesis and CH sub(4) oxidation. Rates of emission show large variation in both space and time and their estimation from point measurements or from correlation with net primary production is difficult and unreliable. Here we report a study in which process-based ecosystem models were used to estimate global CH sub(4) emissions from natural wetlands and rice paddies, and the sensitivity of the models to simple climate change scenarios were tested. Our estimate of global emission was 145 Tg yr super(-1), of which 92 Tg yr super(-1) came from natural wetlands and 53 Tg yr super(-1) from rice paddies. The emissions from wetlands at high-latitude and rice paddies were only half of those reported in the traditional literature, confirming more recent measurements. The models also showed that modest global warming may produce a higher CH sub(4) emission, but that this effect may be reversed by larger increases in temperature, due to the effect of soil moisture depletion.
- Climate forcings in the industrial era
Hansen, JE; Sato, M; Lacis, A; Ruedy, R; Tegen, I; Matthews, E
Proceedings of the National Academy of Sciences, USA [Proc. Natl. Acad. Sci. USA], vol. 95, no. 22, pp. 12753-12758, 27 Oct 1998
The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change. Anthropogenic greenhouse gases (GHGs), which are well measured, cause a strong positive (warming) forcing. But other, poorly measured, anthropogenic forcings, especially changes of atmospheric aerosols, clouds, and land-use patterns cause a negative forcing that tends to offset greenhouse warming. One consequence of this partial balance is that the natural forcing due to solar irradiance changes may play a larger role in the long-term climate change than inferred from comparison with GHGs alone. Current trends in GHG climate forcings are smaller than in popular "business as usual" or 1% per year CO sub(2) growth scenarios. The summary implication is a paradigm change for long-term climate projections: uncertainties in climate forcings have supplanted global climate sensitivity as the predominant issue.
- The curious impact of knowledge about climate change on risk perceptions and willingness to sacrifice
O'Connor, RE; Bord, RJ; Fisher, A
Risk Decision and Policy [Risk Decis. Policy], vol. 3, no. 2, pp. 145-155, Aug 1998
What people know about the causes of climate change matters if that knowledge relates to risk perceptions and the willingness to sacrifice. Self-assessed informedness and the overall ability to differentiate between actual and faux causes of climate change relate to perceived risk, explaining 5% of the variance. But, explained variance increases greatly when knowledge is deconstructed into two components: identification of accurate causes as well as faux causes both relate to a high level of perceived risks. In other words, people who are knowledgeable about actual causes are more likely to foresee a dangerous future, but so are people who believe that pesticides and nuclear power are causing global warming. Self-assessed informedness and the two knowledge variables maintain their significance after adding environmental value scales to the equation. Believing that everything causes global warming correlates with high levels of perceived risk, but does not imply willingness to vote for sacrifices to address those risks. Men are slightly more likely to consider themselves well informed, but women are better able to identify actual causes. Men, however, are less likely to attribute climate change to faux causes than are women.
- A Method for Estimating the Cost of CO sub(2) Mitigation through Afforestation
Plantinga, AJ; Mauldin, T
Climatic Change [Clim. Change], vol. 49, no. 1-2, pp. 21-40, Apr 2001
The Kyoto Protocol allows Annex I countries to use afforestation (the conversion of non-forest land to forest) to meet emissions reduction targets. We present a new method for estimating the cost of CO sub(2) mitigation through afforestation based on econometric models of land use. Land use models are developed from data on observed land allocation decisions and quantify the relationship between the share of land in forest and the net returns to forestry, among other land use determinants. The econometric approach measures the actual responses by landowners to observed changes in net returns, in contrast to earlier studies in which landowner responses are dictated by the researcher. Models are estimated for Maine, South Carolina, and Wisconsin. The estimated models are used to simulate subsidies for afforestation, which imply increases in forest area and net reductions in atmospheric CO sub(2) concentrations. Average cost measures - total subsidies divided by total carbon sequestered - are derived for afforestation programs with and without timber harvesting. The use of econometric land use models in integrated assessments of climate change is explored. We model the effects on land use patterns and the costs of CO sub(2) mitigation of changes in the net returns to agriculture induced by climate change.
- Climate change: Whither after The Hague?
Science (Washington) [Science (Wash.)], vol. 291, no. 5511, pp. 2095-2096, 16 Mar 2001
It is uncommon for major United Nations (U.N.) conferences to fall short of reaching any agreement, but this is what happened at the climate conference in The Hague in November 2000. The reason lies in the diversity of national and commercial interests connected with (and often opposed to) reducing the atmospheric concentration of greenhouse gases (GHGs). The conference in The Hague aimed to define the criteria by which industrialized countries could fulfill their emission targets agreed under the Kyoto Protocol in December 1997. The failure to reach an agreement should not, however, be seen as the death of the Kyoto Protocol. On the contrary, encouraging signals are emerging from industry. Climate change mitigation and adaptation strategies agreed upon at the next conference, which is likely to be held in July this year, must balance the needs of different nations while keeping in mind that taking no action at all will, in the long run, be more expensive than taking preventive action now.
- Cooperation in global climate policy: potentialities and limitations
Ipsen, D; Roesch, R; Scheffran, J
Energy Policy [Energy Policy], vol. 29, no. 4, pp. 315-326, Mar 2001
Since the Kyoto conference the role of the major developing countries (DCs) has been an issue involving a number of conflicting interests. While on the one hand we understand the reasons prompting DCs to refuse obligations to reduce climate gases, their sheer size makes at least the biggest DCs (China, India) major sources of climate gas emissions. Our intention here is to analyze the potentialities for a cooperative solution to this conflict. A conflict model is used to discuss the diverging interests of major DCs and industrialized countries (IC). Concentrating on the power-generation sector, we investigate the conditions for cooperation, i.e. for the DCs' voluntary participation in climate policy in their own interests. In the case of DCs with local environmental goals and ICs interested in joint implementation, secondary benefits provide the basis for cooperation. Thus, the DC's choice of technology becomes the crucial factor in conflict resolution. This enables us to formulate the conditions of cooperation interrelating the DCs' choice of technology and the ICs' investment in joint implementation in such a way as to fulfill both global environmental goals and the DCs' national goals. The example of PR of China illustrates our reasoning.
- Kyoto Protocol: Trade versus the environment
Energy & Environment [Energy Environ.], vol. 12, no. 1, pp. 23-28, 2001
Could the signatories to the Kyoto Protocol find themselves up against the WTO? This paper examines how the climate change agreement could conflict with trade rules, and shows that there are potentially serious conflicts in the interface between the WTO and the Kyoto Protocol. It argues for dialogue and debate before it is too late.
- How could emissions trading benefit developing countries
Energy Policy [Energy Policy], vol. 28, no. 13, pp. 947-956, Nov 2000
This paper aims to show how an emissions trading system could work if some participating entities are allocated an `emissions budget' or non-binding target. This will allow them to sell allowances if their actual emissions are less than their budget, but will not obligate them to buy allowances if their emissions exceed their budget. Different rules aiming at ensuring the environmental integrity of such a system are considered. Parties to the Framework Convention on Climate Change may wish to consider building a regime where developing countries are allocated emissions budgets on some provisions of the Kyoto Protocol and in full respect with the principles of the Convention. In any case such system would be complementary to the Clean Development Mechanism. The potential benefits would be to provide non-Annex-I (developing) countries with substantial capital inflows, and stimulate their economic growth; to allow Annex-I (Industrialized) Countries achieving their Kyoto commitments at the lowest possible cost; and to achieve global participation towards the objective of the Convention while reducing the risk of creating `tropical hot air' by giving some developing countries more allowances than they need under a `business-as-usual' scenario.
- The Kyoto Protocol and payments for tropical forest: An interdisciplinary method for estimating carbon-offset supply and increasing the feasibility of a carbon market under the CDM
Pfaff, ASP; Kerr, S; Hughes, RF; Liu, S; Sanchez-Azofeifa, GA; Schimel, D; Tosi, J; Watson, V
Ecological Economics [Ecol. Econ.], vol. 35, no. 2, pp. 203-221, Nov 2000
Protecting tropical forests under the Clean Development Mechanism (CDM) could reduce the cost of emissions limitations set in Kyoto. However, while society must soon decide whether or not to use tropical forest-based offsets, evidence regarding tropical carbon sinks is sparse. This paper presents a general method for constructing an integrated model (based on detailed historical, remote sensing and field data) that can produce land-use and carbon baselines, predict carbon sequestration supply to a carbon-offsets market and also help to evaluate optimal market rules. Creating such integrated models requires close collaboration between social and natural scientists. Our project combines varied disciplinary expertise (in economics, ecology and geography) with local knowledge in order to create high-quality, empirically grounded, integrated models for Costa Rica.
- Managing carbon from the bottom up
Science (Washington) [Science (Wash.)], vol. 289, no. 5488, p. 2285, 29 Sep 2000
The world needs to get serious about managing the exponential growth of atmospheric carbon dioxide (CO sub(2)). However, because uncertainties about climate science provide convenient political cover for economic interests that favor delay, the United States is unlikely to sign any comprehensive international agreement in the near future. Whether Europe and others can muster the political will to unilaterally implement the Kyoto Protocol is an open question. Even if they do, the Kyoto agreement is at best a modest first step toward the essential goal of stabilizing atmospheric concentrations. Although they may be prepared to take symbolic steps, China, India, Brazil, and other large industrializing states will certainly not agree to serious constraints on their emissions in the near future. Diplomats will put a good face on things, but for at least the next decade, it is unlikely that all the world's major states will simultaneously agree to a serious program to curtail emissions of CO sub(2) and other greenhouse gases.
- Climate change: Equity and greenhouse gas responsibility
Baer, P; Harte, J; Haya, B; Herzog, AV; Holdren, J; Hultman, NE; Kammen, DM*; Norgaard, RB; Raymond, L
Science (Washington) [Science (Wash.)], vol. 289, no. 5488, p. 2287, 29 Sep 2000
Under the Kyoto Protocol, industrialized nations have approved commitments to reduce greenhouse gas (GHG) emissions. These commitments apply only to developed nations, reflecting the international consensus that the industrialized countries should take the lead in mitigating climate change. The U.S. government has made ratification of the Kyoto Protocol conditional on "meaningful participation" by developing nations in mitigating GHG emissions. By impossing this requirement before the long-term equity concerns of developing countries are adequately addressed, the United States may effectively block the implementation of the protocol. Developing countries cannot reasonably be expected to restrict their future emissions without being assured of a fair allocation scheme that will not impair their ability to develop. We argue for the long-term allocation of emissions based on equal rights to the atmospheric commons for every individual (per capita) as a solution to this impasse.
- Carbon sinks in the Kyoto Protocol
Murray, Brian C; Prisley, Stephen P; Birdsey, Richard A; Sampson, RNeil
Journal of Forestry [J For], vol. 98, no. 9, pp. 6-11, Sep 2000
The international agreement known as the Kyoto Protocol seeks to reduce the atmospheric concentration of greenhouse gases to mitigate the threat of global climate change. It contains provisions for including carbon stock changes from forests and land-use change to meet nations' greenhouse gas commitments, but the terms under which forest-related carbon stock changes are included are open to interpretation. Critical questions include how much of the carbon currently being sequestered by US forests might qualify, and what forest management activities will be included.
- The Kyoto Protocol and developing countries
Babiker, M; Reilly, JM*; Jacoby, HD
Energy Policy [Energy Policy], vol. 28, no. 8, pp. 525-536, Jul 2000
Under the Kyoto Protocol, the world's wealthier countries assumed binding commitments to reduce greenhouse gas emissions. The agreement requires these countries to consider ways to minimize adverse effects on developing countries of these actions, transmitted through trade. Using a general equilibrium model of the world economy, we find that adverse effects fall mainly on energy-exporting countries, for some even greater than on countries that are assuming commitments. Removing existing fuel taxes and subsidies and using international permit trading would greatly reduce the adverse impacts and also reduce economic impacts on the countries taking on commitments. Another approach, preferential tariff reduction for developing countries, would benefit many developing countries, but would not target those most adversely affected. If instead, OECD countries directly compensated developing countries for losses, the required annual financial transfer would be on the order of $25 billion (1995 $US) in 2010.
- Equity and the Kyoto Protocol: measuring the distributional effects of alternative emissions trading regimes
Yohe, GW; Montgomery, D; Balistreri, E
Global Environmental Change, Part A: Human and Policy Dimensions [Global Environ. Change Pt. A: Human Policy Dimensions], vol. 10, no. 2, pp. 121-132, Jul 2000
This paper offers a few preliminary steps in bringing the equity implications of building global emissions trading, Annex B trading only, and no trading to the fore as an issue to be considered in the negotiations of how to implement the Kyoto Protocol. All three policy regimes worked within the Charles Rivers State Impacts Assessment Model to make the distribution of per capita gross state product across the United States worse than it would be otherwise, but not significantly. In terms of the distribution of per capita consumption across the states, though, all three of the policy alternatives worked to improve equity (even more) modestly with the largest improvement associated with the "No Trade" option. The equity implications of alternative trading regimes were far more striking in the global context. Global trading did sustain the highest mean in per capita consumption, but the "No Trade" and "Annex B" trading alternatives reduced significantly the underlying inequity in the distribution of per capita. Weighted by a logarithmic utility function, the present value of the certainty equivalent level of mean per capita consumption would fall by more than five times the efficiency gain if global trading were allowed instead of limited Annex B trading. Moreover, this measure of willingness to pay to avoid inequity would be more than eight times larger than the efficiency gain if global trading were chosen over the "No Trade" alternative. The estimates reported here are, of course, highly speculative and extremely model-specific. Different models and, more importantly, different allocations of permits within the United States and/or across the globe would produce different results. The results do not mean that global trading in emissions permits should be shelved because the equity properties are so poor. Much like the other studies that have identified issues that need to be monitored carefully in the design of mechanisms with which the signators of Kyoto Protocol might meet their commitments, though, they do emphatically add equity to the list of fundamental concerns that must be considered.
- The Economics of the Kyoto Protocol
MacCracken, CN; Edmonds, JA; Kim, SH; Sands, RD
Energy Journal [Energy J.], vol. 21, Suppl., pp. 25-72, 2000
In this paper we use the Second Generation Model to develop an assessment of the energy and economic implications of achieving the goals of the Kyoto Protocol. We find that many of the details of the Protocol that remain to be worked out introduce critical uncertainties affecting the cost of compliance. Our analysis shows that the cost of implementing the Protocol in the United States can vary by more than an order of magnitude. The marginal cost in 2010 could be as low as $26 per tonne of carbon if a global system of emissions mitigation could be quickly and effectively implemented. But it could also exceed $250 per tonne of carbon if the United States must meet its emissions limitations entirely through domestic actions, and if mitigation obligations are not adequately anticipated by decision-makers.
- Kyoto, Efficiency, and Cost-Effectiveness: Applications of FUND
Energy Journal [Energy J.], vol. 21, Suppl., pp. 131-156, 2000
In this paper various emission reduction scenarios are evaluated with FUND - the Climate Framework for Uncertainty, Negotiation, and Distribution model. The aim is to help international negotiators improve upon the Kyoto Protocol. International cooperation in greenhouse gas emission reduction is important, and the more of it the better. The emission reduction targets as agreed in the Kyoto Protocol are irreconcilable with economic rationality. If the targets nevertheless need to be met, it is better to start emission reduction sooner than later in order to minimise costs. Methane emission reduction may be an important instrument to reduce costs.
- Clubs, Ceilings and CDM: Macroeconomics of Compliance with the Kyoto Protocol
Bollen, J; Gielen, A; Timmer, H
Energy Journal [Energy J.], vol. 21, Suppl., pp. 177-206, 2000
The Kyoto Protocol suggests that imposing restrictions on emission trade among Annex I countries may force domestic action in each country. The Protocol also mentions the Clean Development Mechanism (CDM) as an instrument to extend trade to countries outside Annex I. We analyze both restrictions on and extensions of permit trade among Annex I countries. We use the applied general equilibrium model WorldScan in this analysis. We show that, compared to unrestricted trade, the USA tends to gain from restrictions on emission trade while other OECD countries are likely to be harmed. We further show that restrictions probably do not prevent so-called hot air in the former Soviet Union from being used. On the contrary, restrictions tend to increase global emissions. Finally, we conclude that CDM can be an efficient option to reduce abatement costs, but certain conditions should be fulfilled to avoid severe carbon leakage.
- Kyoto and technology at world level: costs of CO sub(2) reduction under flexibility mechanisms and technical progress
Criqui, P; Viguier, L
International Journal of Global Energy Issues [Int. J. Global Energy Issues], vol. 14, no. 1-4, pp. 155-168, 2000
This paper is dedicated to the analysis of the consequences of CO sub(2) emission reduction policies, as deriving, in a world perspective, from the Kyoto Protocol for the 2010 horizon. The basic methodological principles for the assessment of the Marginal Abatement Costs and for the quantification of the economic 'gains from trade' in flexibility mechanisms are first presented in Section 2. Section 3 provides a thorough assessment, based on the POLES model results, of the marginal and total costs of compliance to the Kyoto Protocol for a 'non trading' case and for two cases of emission trading, respectively at Annex B level and at world level. Section 4, identifies some possible consequences and policy implications of decisions on 'flexibility mechanisms', particularly in the perspective of induced technical change. It shows that, in principle low flexibility schemes may induce strong price signals in a limited number of constrained countries, while high flexibility schemes may induce lower price signals but on a much broader geographical basis.
- World post-Kyoto scenarios: benefits from accelerated technology progress
Kouvaritakis, N; Criqui, P; Thonet, C
International Journal of Global Energy Issues [Int. J. Global Energy Issues], vol. 14, no. 1-4, pp. 184-203, 2000
This paper addresses the issue of the potential benefits from technological change in post Kyoto CO sub(2) emission reduction scenarios. In order to assess these benefits, it is necessary in Section 2 to define CO sub(2) emission entitlements by world region, in a way that allows both for a significant global reduction from the reference in 2030 and for an acceptable burden sharing among world regions. The economic consequences of this entitlement scenario are explored in detail in Section 3, under the hypotheses of on-going trends for technology dynamics and of full world trading for emission permits. Section 4 then introduces the 'Technology Stories', corresponding to hypotheses of breakthroughs in the performances and costs of six distinct power generation technology clusters. The Technology Stories and their impacts on CO sub(2) marginal and total abatement costs are then studied in detail, both at world level and in a regional perspective. One key result of this paper is a quantitative assessment of the significant reductions in the compliance costs that may be expected from improvements in low-carbon generation technologies.
- Land use, land-use change, forestry, and agricultural activities in the clean development mechanism: Estimates of greenhouse gas offset potential
Bloomfield, J; Pearson, HL
Mitigation and Adaptation Strategies for Global Change [Mitigation Adapt. Strat. Global Change], vol. 5, no. 1, pp. 9-24, 2000
Activities involving land use, land-use change, forestry, and agriculture (LUCF) can help reduce greenhouse gas (GHG) concentrations in the atmosphere by increasing biotic carbon storage, by decreasing GHG emissions, and by producing biomass as a substitute for fossil fuels. Potential activities include reducing rates of deforestation, increasing land devoted to forest plantations, regenerating secondary forest, agroforestry, improving the management of forests and agricultural areas; and producing energy crops. Policymakers debating the inclusion of a variety of LUCF activities in the Clean Development Mechanism (CDM) of the Kyoto Protocol need to consider the magnitude of the carbon contribution these activities could make. Existing estimates of the cumulative GHG offset potential of LUCF activities often take a global or regional approach. In contrast, land-use decisions are usually made at the local level and depend on many factors including productive capacity of the land, financial considerations of the landowner, and environmental concerns. Estimates of GHG offset potential made at a local, or at most country, level that incorporate these factors may be lower, as well as more useful for policy analyses, than global or large regional estimates. While country-level estimates exist for forestry activities, similar estimates utilizing local information need to be generated for agricultural activities and biofuels, as well as for the cumulative potential of all LUCF activities in a particular location.