Climate Change and...
- Climate Variability
- Climate Models
Effects of Climate Change
INTRODUCTION: Global change involves the simultaneous and rapid alteration of several key environmental parameters that control the dynamics of forests. We cannot predict with certainty, through direct experimentation, what the responses of forests to global change will be, because we cannot carry out the multisite, multifactorial experiments required for doing so. The physical extent, complexity, and expense of even single-factor experiments at the scale of the whole ecosystem challenge our abilities, although several such experiments have been successfully undertaken (e.g., DeLucia et al. 1999, Wright and Rasmussen 1998). To inform policy decisions, however, the scientific community can offer an interdisciplinary synthesis of existing information. When this synthesis takes the form of a computer model, quantitative predictions can be made that integrate what has been learned from single-factor experiments. The success of such an approach depends on the quality and completeness of the information base and on the rigor of the modeling effort.
The direct and secondary physiological effects of changes in the physical and chemical climate on plants and soils are relatively well known. We also know which primary environmental drivers—precipitation, temperature, and atmospheric concentrations of carbon dioxide (CO2 ), ozone (O3 ), and nitrogen (N), for example—are being altered by human activities, and we can directly measure temporal change in these parameters. Despite this relatively rich information base, predictions of future responses of forests to environmental change show significant variation. This is due in part to differences between the models of ecosystem function derived from the existing database and in part to differences in climate scenarios generated by the general circulation models (GCMs) used to predict future climates. Understanding both the trend in predicted futures and the uncertainties surrounding those trends is critical to policy formation. At this time, the major mechanism for determining the degree of uncertainty in predictions is through comparison of results from runs of different models using identical input parameters.
The purpose of this article is to review the state of prediction of forest ecosystem response to envisioned changes in the physical and chemical climate. These results are offered as one part of the forest sector analysis of the National Assessment of the Potential Consequences of Climate Variability and Change; other contributions to this assessment appear in this edition of BioScience. This article has three sections. The first offers a very brief review of the literature on the effects of environmental factors on forest ecosystem function (some references are also made to changes in species composition, but Hansen et al.  provide a more complete discussion). The second and largest part of the article is a summary of results from the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), an integrated effort to predict ecosystem response to climate change. The third is a brief review of other regional modeling efforts that have addressed climate change or have looked at the possible effects of other components of global change, using tropospheric ozone and nitrogen deposition as examples, or both.
ABSTRACT: Climate change impacts and responses are presently observed in physical and ecological systems. Adaptation to these impacts is increasingly being observed in both physical and ecological systems as well as in human adjustments to resource availability and risk at different spatial and societal scales. We review the nature of adaptation and the implications of different spatial scales for these processes. We outline a set of normative evaluative criteria for judging the success of adaptations at different scales. We argue that elements of effectiveness, efficiency, equity and legitimacy are important in judging success in terms of the sustainability of development pathways into an uncertain future. We further argue that each of these elements of decision-making is implicit within presently formulated scenarios of socio-economic futures of both emission trajectories and adaptation, though with different weighting. The process by which adaptations are to be judged at different scales will involve new and challenging institutional processes.
R.J. Alig, O. Krankina, A. Yost, J. Kuzminykh (2006). Forest carbon dynamics in the Pacific Northwest (USA) and the St. Petersburg region of Russia: comparisons and policy implications. Climate Change 79 (3-4): 335-360
ABSTRACT: Forests of the United States and Russia can play a positive role in reducing the extent of global warming caused by greenhouse gases, especially carbon dioxide. To determine the extent of carbon sequestration, physical, ecological, economic, and social issues need to be considered, including different forest management objectives across major forest ownership groups. Private timberlands in the U.S. Pacific Northwest are relatively young, well stocked, and sequestering carbon at relatively high rates. Forests in northwestern Russia are generally less productive than those in the Northwestern U.S. but cover extensive areas. A large increase in carbon storage per hectare in live tree biomass is projected on National Forest timberlands in the U.S. Pacific Northwest for all selected scenarios, with an increase of between 157–175 Mg by 2050 and a near doubling of 1970s levels. On private timberlands in the Pacific Northwest, average carbon in live tree biomass per hectare has been declining historically but began to level off near 65 Mg in 2000; projected levels by 2050 are roughly what they were in 1970 at approximately 80 Mg. In the St. Petersburg region, average carbon stores were similar to those on private lands in the Pacific Northwest: 57 Mg per hectare in 2000 and ranging from 40 to 64 Mg by 2050. Although the projected futures reflect a broad range of policy options, larger differences in projected carbon stores result from the starting conditions determined by ownership, regional environmental conditions, and past changes in forest management. However, an important change of forest management objective, such as the end of all timber harvest on National Forests in the Pacific Northwest or complete elimination of mature timber in the St. Petersburg region, can lead to substantial change in carbon stores over the next 50 years.
ABSTRACT: General warming in the Northern Hemisphere has been recorded since the end of the 1800s following the Little Ice Age. Records of glacier retreat during the last 100 years over the entire globe independently confirmed the recorded trend in global temperature rise. Several studies have illustrated various responses to this climate forcing, i.e., the recorded changes in temperature and precipitation concurrent with the increase in atmospheric CO2 concentration, increases in density of tree populations, declines in tree populations, treeline displacement or lack thereof, lengthening of the growing season, and enhanced tree growth. It is critical that we identify the tools needed to estimate potential consequences of climate change on forest ecosystems and develop management practices and policies adapted to projected drifts in the geographic distribution of ecosystems.
Brody, S. D., Zahran, S., Grover, H., Vedlitz, A. (2008). A spatial analysis of local climate change policy in the United States: risk, stress, and opportunity. Landscape and Urban Planning 87 (1): 33-41
ABSTRACT: This study examines the factors motivating local jurisdictions in the United States (U.S.) to voluntarily adopt policies that mitigate the anthropogenic sources of climate change when there are powerful political and economic incentives to do otherwise. Specifically, we explain adoption of the Cities for Climate Protection (CCP) program at the county level with indicators of climate change risk, climate stress, and opportunity for climate policy action. Statistical and spatial results indicate that counties with high risk, low stress, and high opportunity characteristics associated with climate change are significantly more likely to join the CCP campaign. Results also show that the odds of a locality joining the CCP are predictable by the landscape characteristics of spatial neighbors. Identifying a profile for likely adoption of climate change mitigation strategies can help decision makers effectively target local jurisdictions for recruitment into the CCP and similar programs in the future.
ABSTRACT: Forests are important in the global carbon cycle, forming a major sink for carbon. Deforestation is a significant source of carbon dioxide emitted to the atmosphere. There is some scope to enhance natural carbon sinks, and therefore reduce net emissions of greenhouse gases, through afforestation and conservation of existing forests. Such initiatives may be implemented to “offset” emissions of greenhouse gases from other sources. This may be undertaken by private companies, or by governments as part of bilateral agreements or multilateral arrangements. International carbon offsets may be cost effective in terms of reduction of carbon emissions achieved, and may also be one way to mobilise private capital to fund forest conservation. It is argued here that theoretically the international offset of emissions may lead to a resource saving, and that forest conservation, as opposed to afforestation, may bring about many other benefits. However, such international contracts are unlikely to be feasible or make a major contribution to the control of greenhouse gases. The reasons for this are monitoring, enforcement and scientific uncertainties, and the implicit change in property rights involved in “selling” carbon sequestration rights.
CCSP, P. Backlund, A. Janetos, D. Schimel, J. Hatfield, K. Boote, P. Fay, L. Hahn, C. Izaurralde, B.A. Kimball, T. Mader, J. Morgan, D. Ort, W. Polley, A. Thomson, D. Wolfe, M. Ryan, S. Archer, R. Birdsey, C. Dahm, L. Heath, J. Hicke, D. Hollinger, T. Huxman, G. Okin, R. Oren, J. Randerson, W. Schlesinger, D. Lettenmaier, D. Major, L. Poff, S. Running, L. Hansen, D. Inouye, B.P. Kelly, L Meyerson, B. Peterson, R. Shaw (2008a). The effects of climate change on agriculture, land resources, water resources, and biodiversity. U.S. Environmental Protection Agency: 362 p.
- Climate change is already affecting U.S. water resources, agriculture, land resources, and biodiversity, and will continue to do so.
- Grain and oilseed crops will mature more rapidly, but increasing temperatures will increase the risk of crop failures, particularly if precipitation decreases or becomes more variable.
- Higher temperatures will negatively affect livestock. Warmer winters will reduce mortality but this will be more than offset by greater mortality in hotter summers. Hotter temperatures will also result in reduced productivity of livestock and dairy animals.
- Forests in the interior West, the Southwest, and Alaska are already being affected by climate change with increases in the size and frequency of forest fires, insect outbreaks and tree mortality. These changes are expected to continue.
- Much of the United States has experienced higher precipitation and streamflow, with decreased drought severity and duration, over the 20th century. The West and Southwest, however, are notable exceptions, and increased drought conditions have occurred in these regions.
- Weeds grow more rapidly under elevated atmospheric CO2 . Under projections reported in the assessment, weeds migrate northward and are less sensitive to herbicide applications.
- There is a trend toward reduced mountain snowpack and earlier spring snowmelt runoff in the Western United States.
- Horticultural crops (such as tomato, onion, and fruit) are more sensitive to climate change than grains and oilseed crops.
- Young forests on fertile soils will achieve higher productivity from elevated atmospheric CO2 concentrations. Nitrogen deposition and warmer temperatures will increase productivity in other types of forests where water is available.
- Invasion by exotic grass species into arid lands will result from climate change, causing an increase fire frequency. Rivers and riparian systems in arid lands will be negatively impacted.
- A continuation of the trend toward increased water use efficiency could help mitigate the impacts of climate change on water resources.
PREFACE: The U.S. Government’s Climate Change Science Program (CCSP) is responsible for providing the best science-based knowledge possible to inform management of the risks and opportunities associated with changes in the climate and related environmental systems. To support its mission, the CCSP has commissioned 21 “synthesis and assessment products” (SAPs) to advance decisionmaking on climate change-related issues by providing current evaluations of climate change science and identifying priorities for research, observation, and decision support. This Report—SAP 4.4—focuses on federally managed lands and waters to provide a “Preliminary Review of Adaptation Options for Climate-Sensitive Ecosystems and Resources.” It is one of seven reports that support Goal 4 of the CCSP Strategic Plan to understand the sensitivity and adaptability of different natural and managed ecosystems and human systems to climate and related global changes.
The purpose of SAP 4.4 is to provide useful information on the state of knowledge regarding adaptation options for key, representative ecosystems and resources that may be sensitive to climate variability and change. As its title suggests, this report is a preliminary review, defined as “the process of collecting and reviewing available information about known or potential adaptation options.” The Intergovernmental Panel on Climate Change (IPCC) notes that there are few demonstrated examples of ecosystem-focused adaptation options (see IPCC Fourth Assessment Report, 18.104.22.168 and 4.6.2). Thus, the authors of this SAP found it necessary to examine adaptation options in the context of a desired ecosystem condition or natural resource management goal, as set forth by the resource management entity. Therefore, this report explores potential adaptation options that could be used by natural resource managers within the context of the legislative and administrative mandates of the six systems examined: National Forests, National Parks, National Wildlife Refuges, Wild and Scenic Rivers, National Estuaries, and Marine Protected Areas. Case studies throughout this report examine in greater detail some of the issues and challenges associated with implementation of adaptation options, but are not intended to be geographically comprehensive or representative of the full breadth of ecosystems that exist or adaptation options that are available.
The management systems selected for this report are meant to be representative of a variety of ecosystem types and management goals, in order to be useful to managers who work at different spatial and organizational scales. Time and resource constraints do not allow for a comprehensive coverage of all federally owned and managed lands and waters, which means that some important management systems (e.g., Bureau of Land Management lands, Department of Defense lands, tribal lands, research reserves) are not featured in this report. However, this preliminary review of existing adaptation knowledge does contain science-based adaptation strategies that are broadly applicable to not only other federal lands, but also state, local, territorial, tribal, and non-governmental holdings. Adaptive Management, a key tool recognized in this report, is an important concept within the Department of the Interior, and an Adaptive Management Technical Guide1 was released in the spring of 2007. It provides a robust analytical framework that is based on the experience, in-depth consultation, and best practices of scientists and natural resource managers. The information in this SAP combined with Interior’s Technical Guide is available for managers to consider and discuss. Additional work is needed to refine and add to this body of knowledge, including conducting detailed analyses of adaptation options on a case-by-case basis.
It must be noted that a discussion of the cost and benefits of implementing the adaptation options, either individually or collectively, was not a component of the SAP prospectus and is not included in this report. Relative to ecosystems, the IPCC noted that information is very limited on the economic and social costs and benefits of adaptation measures, especially the non-market costs and benefits of adaptation measures involving ecosystem protection, among others. Since this is a preliminary report, additional information on the costs and benefits is certainly warranted.
ABSTRACT: While there is no question that successful mitigation strategies remain critical in the quest to avoid worst-case climate change scenarios, we’ve passed the point where mitigation efforts alone can deal with the problems that climate change is creating. Because of “committed” warming – climate change that will occur regardless of mitigation measures, a result of the already-accumulated greenhouse gases in the atmosphere – what happens to social-ecological systems over the next decades, and most likely over the next few centuries, will largely be beyond human control. The time to start preparing for these changes is now, by making adaptation part of a national climate change policy.
Nevertheless, American law and policy are not keeping up with the need for adaptation, even though adapting law to a world of continuing climate change impacts will be a far more complicated task than addressing mitigation. Environmental and natural resources law, for example, are currently based on assumptions of ecological stationarity and pursue goals of preservation and restoration. Neither those assumptions nor those goals fit a world of continual, unpredictable, and nonlinear transformations of complex ecosystems – but that is the world that climate change impacts are creating.
This Article argues for a principled flexibility model of climate change adaptation law to pursue goals of increasing the resilience and adaptive capacity of social-ecological systems. In so doing, it lays out five principles and several sub-principles for the law of environmental regulation and natural resources management. Structurally, this Article also strongly suggests that climate change adaptation law must be bimodal: it must promote informed and principled flexibility when dealing with climate change impacts, especially impacts that affect baseline ecological conditions such as temperature and hydrology, while simultaneously embracing an unyielding commitment to precautionary regulation when dealing with everything else.
ABSTRACT: The adaptability of North American agriculture to climate change is assessed through a review of current literature. A baseline of North American agriculture without climate change suggests that farming faces serious challenges in the future (e.g. declining domestic demand, loss of comparative advantage, rising environmental costs). Climate change adjustments at the farm-level and in government policy, including international trade policy, are inventoried from the literature. The adaptive potential of agriculture is demonstrated historically with situations that are analogous to climate change, including the translocation of crops across natural climate gradients, the rapid introduction of new crops such as soybeans in the US and canola in Canada, and resource substitutions prompted by changes in prices of production inputs. A wide selection of modeling studies is reviewed which, in net, suggests several agronomic and economic adaptation strategies that are available to agriculture. Agronomic strategies include changes in crop varieties and species, timing of operations, and land management including irrigation. Economic strategies include investment in new technologies, infrastructure and labor, and shifts in international trade. Overall, such agronomic strategies were found to offset either partially or completely the loss of productivity caused by climate change. Economic adaptations were found to render the agricultural costs of climate change small by comparison with the overall expansion of agricultural production. New avenues of adaptive research are recommended including the formalization of the incorporation of adaptation strategies into modeling, linkage of adaptation to the terrestrial carbon cycle, anticipation of future technologies, attention to scaling from in situ modeling to the landscape scale, expansion of data sets and the measurement and modeling of unpriced costs. The final assessment is that climate change should not pose an insurmountable obstacle to North American agriculture. The portfolio of assets needed to adapt is large in terms of land, water, energy, genetic diversity, physical infrastructure and human resources, research capacity and information systems, and political institutions and world trade—the research reviewed here gives ample evidence of the ability of agriculture to utilize such assets. In conclusion, the apparent efficiency with which North American agriculture may adapt to climate changes provides little inducement for diverting agricultural adaptation resources to efforts to slow or halt the climate changes.
C. N. Ehler, B. Cicin-Sain, R. Knecht, R. South, R. Weiher (1997). Guidelines to assist policy makers and managers of coastal areas in the integration of coastal management programs and national climate-change action plans. Ocean & Coastal Management 37 (1): 7-27
ABSTRACT: In response to potential commitments and obligations under the United Nations Framework Convention on Climate Change (UNFCCC), many nations are preparing national climate change action plans that identify management strategies to reduce greenhouse gas emissions and to adapt to the potential impacts of long-term climate change. The successful implementation of these plans and their management strategies within individual countries will depend to a large measure on the extent of their integration into the implementation of other national and sectoral management plans, including coastal management plans. This document provides guidance on integrating coastal management programs and national climate-change action plans.
ABSTRACT: Carbon sequestration programs, including afforestation and reforestation, are gaining attention globally and will alter many ecosystem processes, including water yield. Some previous analyses have addressed deforestation and water yield, while the effects of afforestation on water yield have been considered for some regions. However, to our knowledge no systematic global analysis of the effects of afforestation on water yield has been undertaken. To assess and predict these effects globally, we analyzed 26 catchment data sets with 504 observations, including annual runoff and low flow. We examined changes in the context of several variables, including original vegetation type, plantation species, plantation age, and mean annual precipitation (MAP). All of these variables should be useful for understanding and modeling the effects of afforestation on water yield. We found that annual runoff was reduced on average by 44% (±3%) and 31% (±2%) when grasslands and shrublands were afforested, respectively. Eucalypts had a larger impact than other tree species in afforested grasslands (P=0.002), reducing runoff (90) by 75% (±10%), compared with a 40% (±3%) average decrease with pines. Runoff losses increased significantly with plantation age for at least 20 years after planting, whether expressed as absolute changes (mm) or as a proportion of predicted runoff (%) (P<0.001). For grasslands, absolute reductions in annual runoff were greatest at wetter sites, but proportional reductions were significantly larger in drier sites (P<0.01 and P<0.001, respectively). Afforestation effects on low flow were similar to those on total annual flow, but proportional reductions were even larger for low flow (P<0.001). These results clearly demonstrate that reductions in runoff can be expected following afforestation of grasslands and shrublands and may be most severe in drier regions. Our results suggest that, in a region where natural runoff is less than 10% of MAP, afforestation should result in a complete loss of runoff; where natural runoff is 30% of precipitation, it will likely be cut by half or more when trees are planted. The possibility that afforestation could cause or intensify water shortages in many locations is a tradeoff that should be explicitly addressed in carbon sequestration programs.
B. Felzer, J. Reilly, J. Melillo, D. Kicklighter, M. Sarofim, C. Wang, R. Prinn, Q. Zhuang (2005). Future effects of ozone on carbon sequestration and climate change policy using a global biogeochemical model. Climatic Change 73 (3): 345-373
ABSTRACT: Exposure of plants to ozone inhibits photosynthesis and therefore reduces vegetation production and carbon sequestration. The reduced carbon storage would then require further reductions in fossil fuel emissions to meet a given CO2 concentration target, thereby increasing the cost of meeting the target. Simulations with the Terrestrial Ecosystem Model (TEM) for the historical period (1860–1995) show the largest damages occur in the Southeast and Midwestern regions of the United States, eastern Europe, and eastern China. The largest reductions in carbon storage for the period 1950–1995, 41%, occur in eastern Europe. Scenarios for the 21st century developed with the MIT Integrated Global Systems Model (IGSM) lead to even greater negative effects on carbon storage in the future. In some regions, current land carbon sinks become carbon sources, and this change leads to carbon sequestration decreases of up to 0.4 Pg C yr−1 due to damage in some regional ozone hot spots. With a climate policy, failing to consider the effects of ozone damage on carbon sequestration would raise the global costs over the next century of stabilizing atmospheric concentrations of CO2 equivalents at 550 ppm by 6 to 21%. Because stabilization at 550 ppm will reduce emission of other gases that cause ozone, these additional benefits are estimated to be between 5 and 25% of the cost of the climate policy. Tropospheric ozone effects on terrestrial ecosystems thus produce a surprisingly large feedback in estimating climate policy costs that, heretofore, has not been included in cost estimates.
Feroz, E. H., Raab, R. L., Ulleberg, G. T., Alsharif, K. (2009). Global warming and environmental production efficiency ranking of the Kyoto Protocol nations. Journal of Environmental Management 90 (2): 1178-1183
ABSTRACT: This paper analyzes the United Nations Organization's Kyoto Protocol nations to address two questions. First, what are the environmental production efficiency rankings of these nations? Second, is there a relationship between a nation's ratification status and its environmental production efficiency ranking? Our findings suggest that the nations that have ratified the Kyoto Protocol are more likely to be environmentally production efficient as compared to the nations that have not ratified the Protocol.
ABSTRACT: When included as part of a larger greenhouse gas (GHG) emissions reduction program, forest offsets may provide low-cost opportunities for GHG mitigation. One barrier to including forest offsets in climate policy is the risk of reversal, the intentional or unintentional release of carbon back to the atmosphere due to storms, fire, pests, land use decisions, and many other factors. To address this shortcoming, a variety of different strategies have emerged to minimize either the risk or the financial and environmental implications of reversal. These strategies range from management decisions made at the individual stand level to buffers and set-asides that function across entire trading programs. For such strategies to work, the actual risk and magnitude of potential reversals need to be clearly understood. In this paper we examine three factors that are likely to influence reversal risk: natural disturbances (such as storms, fire, and insect outbreaks), climate change, and landowner behavior. Although increases in atmospheric CO2 and to a lesser extent warming will likely bring benefits to some forest ecosystems, temperature stress may result in others. Furthermore, optimism based on experimental results of physiology and growth must be tempered with knowledge that future large-scale disturbances and extreme weather events are also likely to increase. At the individual project level, management strategies such as manipulation of forest structure, age, and composition can be used to influence carbon sequestration and reversal risk. Because some management strategies have the potential to maximize risk or carbon objectives at the expense of the other, policymakers should ensure that forest offset policies and programs do not provide the singular incentive to maximize carbon storage. Given the scale and magnitude of potential disturbance events in the future, however, management decisions at the individual project level may be insufficient to adequately address reversal risk; other, non-silvicultural strategies and policy mechanisms may be necessary. We conclude with a brief review of policy mechanisms that have been developed or proposed to help manage or mitigate reversal risk at both individual project and policy-wide scales.
ABSTRACT: According to experts at the GAO workshop, federal land and water resources are vulnerable to a wide range of effects from climate change, some of which are already occurring. These effects include, among others, (1) physical effects, such as droughts, floods, glacial melting, and sea level rise; (2) biological effects, such as increases in insect and disease infestations, shifts in species distribution, and changes in the timing of natural events; and (3) economic and social effects, such as adverse impacts on tourism, infrastructure, fishing, and other resource uses.
Experts at the GAO workshop also identified several challenges that resource managers face in addressing the observed and potential effects of climate change in their management and planning efforts. In particular, BLM, FS, FWS, NOAA, and NPS have not made climate change a priority, and the agencies’ strategic plans do not specifically address climate change. Resource managers focus first on near-term, required activities, leaving less time for addressing longer-term issues such as climate change.
In addition, resource managers have limited guidance about whether or how to address climate change and, therefore, are uncertain about what actions, if any, they should take. In general, resource managers lack specific guidance for incorporating climate change into their management actions and planning efforts. Without such guidance, their ability to address climate change and effectively manage resources is constrained. While a broad order developed in January 2001 directed BLM, FWS, and NPS to consider and analyze potential climate change effects in their management plans and activities, the agencies have not yet provided specific direction to managers on how they are to implement the order. A BLM official stated at an April 2007 hearing that BLM is establishing policy and technical committees to address necessary actions and develop guidance to address climate change in agency management practices. FWS and NPS officials said that their agencies have not developed specific guidance but believe that they are operating in a manner consistent with the 2001 order. While NOAA and FS have not provided specific guidance to their resource managers, NOAA officials said that the agency is establishing a working group to determine what actions to take to address climate change effects. FS officials said that FS planning processes are designed to identify and respond to emerging issues such as climate change.
Finally, resource managers do not have sufficient site-specific information to plan for and manage the effects of climate change on the federal resources they manage. In particular, the managers lack computational models for local projections of expected changes and detailed inventories and monitoring systems for an adequate baseline understanding of existing local species. Without such information, managers are limited to reacting to already-observed climate change effects on their units, which makes it difficult to plan for future changes.
R. E. Gullison, P. C. Frumhoff, J. G. Canadell, C. B. Field, D. C. Nepstad, K. Hayhoe, R. Avissar, L. M. Curran, P. Friedlingstein, C. D. Jones, C. Nobre (2007). Tropical forests and climate policy. Science 316 (5827): 985-986
ABSTRACT: New science underscores the value of a climate policy initiative to reduce emissions from tropical deforestation.
ABSTRACT: Current debate on policies for limiting climate change due to greenhouse-gas emissions focuses on whether to take action now or later, and on how stringent any emissions reductions should be in the near and long term. Any reductions policies implemented now will need to be revised later as scientific understanding of climate change improves. Here we consider the effects of a sequential-decision strategy (Fig. 1) consisting of a near-term period (1992–2002) during which either moderate emissions reductions (achieved by energy conservation only) or aggressive reductions (energy conservation coupled with switching to other fuel sources) are begun, and a subsequent long-term period during which a least-cost abatement policy is followed to limit global mean temperature change to an optimal targetDT *. For each policy we calculate the global mean surface temperature changeDT(t ) using a simple climate/ocean model for climate sensitivitiesDT2x . (the response to doubled CO2 , concentrations) of 4.5,2.5,1.5 and 0.5 °C. The policy beginning with moderate reductions is less expensive than that with aggressive reductions ifDT *>2.9, 2.1, 1.5 and 0.9 °C respectively; otherwise, the aggressive-reductions policy is cheaper. We suggest that this approach should assist in choosing realistic targets and in determining how best to implement emissions reductions in the short and long term.
ABSTRACT: While the scientific evidence for climate change grows, the policy responses have so far had little or no impact on the build-up of emissions. Current trends in emissions are adverse. The paper considers why the disconnect between science and policy exists and, in particular, why the Kyoto Protocol has achieved so little. Some contributing factors considered are: the focus on carbon production rather than consumption in the architecture of Kyoto; the flaws in the analysis presented in the Stern Report (notably on the impacts of climate change on economic growth, on the costs of mitigation, and on discounting); and the political economy of the choice of policy instruments, the politics of the rents that arise, and the technology bias. The challenges facing the Copenhagen conference are noted, and it is concluded that, with a recasting of the economics of climate change, the prospects for closing the gap between the science and policy are grim.
NOTES: Prepared by the Governor's Advisory Group on Global Warming and partially based on the June 15, 2004 proceedings of a symposium entitled "Impacts of Climate Change on the Pacific Northwest" in Corvallis, Oregon. The document is signed by 49 Ph.D.-level scientists with expertise on the impacts of climate change.
Recent climate changes include: since the beginning of the 20th century, a 10% increase in annual precipitation across the region with increases of 30-40% in eastern Washington and northern Idaho. Sea level increase of 1.5-2 mm per year; a decline in April 1 snowpack and 50% decline in snow water equivalent (SWE) during the period 1950-2000. Timing of the peak snowpack is earlier in the year, with increase in March streamflow and decrease in June streamflow.
Expected changes include: an increase in average annual temperature of 2.7 degrees F by 2030 and 5.4 degrees F by 2050. This is likely to result in higher elevation treeline and longer fire season, among other changes. Oregon is expected to remain a winter-dominant precipitation regime, but with less snowfall and more rain, especially at lower elevations. Changes in precipitation (increase or decrease) are less certain. Peak hydropower capacity may shift more to winter months; summer stream temperatures will likely increase. Deep ocean circulation willcontinue to change. Since 1920, nearly every temperature monitoring station in the Pacific Northwest shows a warming trend (Mote 2003).
INTRODUCTION: The Working Group I contribution to the IPCC Fourth Assessment Report describes progress in understanding of the human and natural drivers of climate change1 , observed climate change, climate processes and attribution, and estimates of projected future climate change. It builds upon past IPCC assessments and incorporates new findings from the past six years of research. Scientific progress since the TAR is based upon large amounts of new and more comprehensive data, more sophisticated analyses of data, improvements in understanding of processes and their simulation in models, and more extensive exploration of uncertainty ranges.
The basis for substantive paragraphs in this Summary for Policymakers can be found in the chapter sections specified in curly brackets.
ABSTRACT: There is increasing scientific evidence to suggest that humans are gradually but certainly changing the Earth's climate. In an effort to prevent further damage to the fragile atmosphere, and with the belief that action is required now, the scientific community has been prolific in its dissemination of information on climate change. Inspired by the results of the Intergovernmental Panel on Climate Change's Second Assessment Report, Jepma and Munasinghe set out to create a concise, practical, and compelling approach to climate change issues. They deftly explain the implications of global warming, and the risks involved in attempting to mitigate climate change. They look at how and where to start action, and what organization is needed to be able to implement the changes. This book represents a much needed synopsis of climate change and its real impacts on society. It will be an essential text for climate change researchers, policy analysts, university students studying the environment, and anyone with an interest in climate change issues. A digestible version of the IPCC 1995 Economics Report - written by two of IPCC contributors with a Foreword by two of the editors of Climate Change 1995: Economics of Climate Change: i.e. has unofficial IPCC approval Focusses on policy and economics - important but of marginal interest to scientists, who are more likely to buy this summary than the full IPCC report itself Has case-studies to get the points across Separate study guide workbook will be available, mode of presentation (Web or book) not yet finalized
ABSTRACT: Carbon (C) sequestration in soil implies enhancing the concentrations/pools of soil organic matter and secondary carbonates. It is achieved through adoption of recommended management practices (RMPs) on soils of agricultural, grazing, and forestry ecosystems, and conversion of degraded soils and drastically disturbed lands to restorative land use. Of the 916 million hectares (Mha) comprising the total land area in the continental United States and Alaska, 157 Mha (17.1%) are under cropland, 336 Mha (36.7%) under grazing land, 236 Mha (25.8%) under forest, 14 Mha (1.5%) under Conservation Reserve Programs (CRP), and 20 Mha (2.2%) are under urban land use. Land areas affected by different soil degradative processes include 52 Mha affected by water erosion, 48 Mha by wind erosion, 0.2 Mha by secondary salinization, and more than 4 Mha affected by mining. Adoption of RMPs can lead to sequestration of soil organic carbon (SOC) at an annual rate of 45 to 98 Tg (teragram = 1 × 1012 g = 1 million metric tons or MMT) in cropland, 13 to 70 Tg in grazing land, and 25 to 102 Tg in forestlands. In addition, there is an annual soil C sequestration potential of 21 to 77 Tg by land conversion, 25 to 60 Tg by land restoration, and 15 to 25 Tg by management of other land uses. Thus, the total potential of C sequestration in soils of the United States is 144 to 432 Tg/y or an average of 288 Tg C/y. With the implementation of suitable policy initiatives, this potential is realizable for up to 30 years or when the soil C sink capacity is filled. In comparison, emission by agricultural activities is estimated at 43 Tg C/y, and the current rate of SOC sequestration is reported as 17 Tg C/y. The challenge the policy makers face is to be able to develop and implement policies that are conducive to realization of this potential.
Makundi, W.R. (1997). Global climate change mitigation and sustainable forest management — the challenge of monitoring and verification. Mitigation and Adaptation Strategies for Global Change 2: 133-155
ABSTRACT: In this paper, sustainable forest management is discussed within the historical and theoretical framework of the sustainable development debate. The various criteria and indicators for sustainable forest management put forth by different institutions are critically explored. Specific types of climate change mitigation policies/projects in the forest sector are identified and examined in the light of the general criteria for sustainable forest management. Areas of compatibility and contradiction between the climate mitigation objectives and the minimum criteria for sustainable forest management are identified and discussed. Emphasis is put on the problems of monitoring and verifying carbon benefits associated with such projects given their impacts on pre-existing policy objectives on sustainable forest management. The implications of such policy interactions on assignment of carbon credits from forest projects under Joint Implementation/Activities Implemented Jointly initiatives are discussed. The paper concludes that a comprehensive monitoring and verification regime must include an impact assessment on the criteria covered under other agreements such as the Biodiversity and/or Desertification Conventions. The actual carbon credit assigned to a specific project should at least take into account the negative impacts on the criteria for sustainable forest management. The value of the impacts and/or the procedure to evaluate them need to be established by interested parties such as the Councils of the respective Conventions.
G. Marland, R.A. Pielke, Sr., M. Apps, R. Avissar, R. A. Betts, K.J. Davis, P.C. Frumhoff, S.T. Jackson, L.A. Joyce, P. Kauppi, J. Katzenberger, K. G. MacDicken, R. P. Neilson, J. O. Niles, D. S. Niyogi, R. J. Norby, N. Pena, N. Sampson, Y. Xue (2003). The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy. Climate Policy 3 (2): 149-157
ABSTRACT: Strategies to mitigate anthropogenic climate change recognize that carbon sequestration in the terrestrial biosphere can reduce the build-up of carbon dioxide in the Earth’s atmosphere. However, climate mitigation policies do not generally incorporate the effects of these changes in the land surface on the surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. Changes in these components of the surface energy budget can affect the local, regional, and global climate. Given the goal of mitigating climate change, it is important to consider all of the effects of changes in terrestrial vegetation and to work toward a better understanding of the full climate system. Acknowledging the importance of land surface change as a component of climate change makes it more challenging to create a system of credits and debits wherein emission or sequestration of carbon in the biosphere is equated with emission of carbon from fossil fuels. Recognition of the complexity of human-caused changes in climate does not, however, weaken the importance of actions that would seek to minimize our disturbance of the Earth’s environmental system and that would reduce societal and ecological vulnerability to environmental change and variability.
ABSTRACT: Climate policy decisions are being made despite layers of uncertainty. Such decisions directly influence the potential for "dangerous anthropogenic interference with the climate system." We mapped a metric for this concept, based on Intergovernmental Panel on Climate Change assessment of climate impacts, onto probability distributions of future climate change produced from uncertainty in key parameters of the coupled social-natural system—climate sensitivity, climate damages, and discount rate. Analyses with a simple integrated assessment model found that, under midrange assumptions, endogenously calculated, optimal climate policy controls can reduce the probability of dangerous anthropogenic interference from ~45% under minimal controls to near zero.
INTRODUCTION: Atmospheric concentrations of carbon dioxide (CO2 ) and other greenhouse gases have been increasing since the beginning of the industrial revolution in 1850. Over the next century, increasing gas concentrations could cause the temperature on the surface of the Earth to rise as much as 2–3°C over historic mean annual levels. Variation in annual climate could also increase.
The United States experienced one indication of climate change in 1988: The summer of that year was one of the hottest, driest ever recorded across the nation. Barges were stranded on the Mississippi River, and forest fires burned millions of acres in the western United States. In the eastern United States, temperatures were so high that many factory assembly lines had to be shut down. The former Soviet Union states and China also experienced severe drought, while Africa, India, and Bangladesh witnessed torrential rains and flooding.
These events triggered televised congressional debates, which concluded that atmospheric greenhouse gas inputs would very likely increase the intensity and severity of weather patterns during the next 100 years. The potential negative effects of global warming—melting of polar ice caps, a rise in the sea level, reduced agricultural and forest productivity, water shortages, and extinction of sensitive species—were also discussed.
These findings prompted the passage of the 1990 Global Change Research Act (GCRA) and the establishment of the US Global Change Research Program (USGCRP). The program sponsors ongoing research (over $1.6 billion in 2000) at several federal agencies, including the National Aeronautics and Space Administration, Department of Energy, US Department of Agriculture, Environmental Protection Agency, National Institutes of Health, Department of Commerce, and National Science Foundation, among others (USGCRP 1999). In addition to providing a mechanism for funding research on global change, the GCRA mandates that an assessment be conducted periodically to summarize research findings. Begun in 1997, the first National Assessment of the Potential Consequences of Climate Variability and Change was published in 2001 (USGCRP 2001). The assessment was a collaboration between federal and nonfederal researchers, resource managers, and users. The assessment is divided into five sectors: (1) water resources and availability, (2) agriculture and food production, (3) human health, (4) coastal areas, and (5) forests. These sectors represent important or potentially sensitive US resources that could be adversely affected by climate change. The assessment also includes over 20 regional studies, which examine the impacts of climate change for specific geographical areas of the United States. This special section of BioScience focuses on a summary of research findings from the forest sector and regional findings of the 2001 national assessment (USGCRP 2001).
The impacts of climate change on the forest sector are divided into four categories: (1) forest processes, (2) biodiversity change, (3) disturbance interactions, and (4) socioeconomic change. These categories represent key interactions between a changing climate, forest structure or function, and human interactions with forests.
ABSTRACT: Equity discussions in climate change policy focus on mitigation. Climate change impacts, adaptation and decision making are also important. General equity principles can be related to specific proposals for equitable sharing of mitigation but no objective preference for any principle exists. Most promising are mixed approaches, that combine various equity principles in a process oriented setting.
M. Milinski, D. Semmann, H. Krambeck, J. Marotzke (2006). Stabilizing the Earth’s climate is not a losing game: Supporting evidence from public goods experiments. Proceedings of the National Academy of Sciences 103 (11): 3994-2998
ABSTRACT: Maintaining the Earth’s climate within habitable boundaries is probably the greatest "public goods game" played by humans. However, with >6 billion "players" taking part, the game seems to rule out individual altruistic behavior. Thus, climate protection is a problem of sustaining a public resource that everybody is free to overuse, a "tragedy of the commons" problem that emerges in many social dilemmas. We perform a previously undescribed type of public goods experiment with human subjects contributing to a public pool. In contrast to the standard protocol, here the common pool is not divided among the participants; instead, it is promised that the pool will be invested to encourage people to reduce their fossil fuel use. Our extensive experiments demonstrate that players can behave altruistically to maintain the Earth’s climate given the right set of circumstances. We find a nonzero basic level of altruistic behavior, which is enhanced if the players are provided with expert information describing the state of knowledge in climate research. Furthermore, personal investments in climate protection increase substantially if players can invest publicly, thus gaining social reputation. This increase occurs because subjects reward other subjects’ contributions to sustaining the climate, thus reinforcing their altruism. Therefore, altruism may convert to net personal benefit and to relaxing the dilemma if the gain in reputation is large enough. Our finding that people reward contributions to sustaining the climate of others is a surprising result. There are obvious ways these unexpected findings can be applied on a large scale.
ABSTRACT: We offer a conceptual framework for managing forested ecosystems under an assumption that future environments will be different from present but that we cannot be certain about the specifics of change. We encourage flexible approaches that promote reversible and incremental steps, and that favor ongoing learning and capacity to modify direction as situations change. We suggest that no single solution fits all future challenges, especially in the context of changing climates, and that the best strategy is to mix different approaches for different situations. Resources managers will be challenged to integrate adaptation strategies (actions that help ecosystems accommodate changes adaptively) and mitigation strategies (actions that enable ecosystems to reduce anthropogenic influences on global climate) into overall plans. Adaptive strategies include resistance options (forestall impacts and protect highly valued resources), resilience options (improve the capacity of ecosystems to return to desired conditions after disturbance), and response options (facilitate transition of ecosystems from current to new conditions). Mitigation strategies include options to sequester carbon and reduce overall greenhouse gas emissions. Priority-setting approaches (e.g., triage), appropriate for rapidly changing conditions and for situations where needs are greater than available capacity to respond, will become increasingly important in the future.
INTRODUCTION: Climatic variations and climate change may affect the abundance, availability and even the continued existence of a wide range of natural resources. Many of these resources are not owned and controlled as private property. Rather, they are common or public property resources that are managed with varying degrees of effectiveness by local, national or international public authorities. Marine fisheries, particularly those exploited by more than one nation, are notable examples of climate-sensitive resources whose management is complicated by the difficulty of defining and enforcing exclusive rights to the resource.
The Pacific salmon stocks of North America are transboundary resources in that they cross state and international boundaries in their oceanic migrations. There are five species of Pacific salmon (chinook, coho, sockeye, pink and chum), with a multitude of distinct breeding populations. While the various species, and even different stocks of the same species, follow somewhat different life histories, all Pacific salmon are anadromous. In other words, they spawn in freshwater streams. The juveniles migrate to the ocean where they often traverse enormous distances as they feed and mature. Mature salmon then return to their natal streams to spawn and die. Their anadromous nature makes salmon sensitive to changes both in the ocean and stream environments. It also creates a perplexing set of difficulties for effective management.
The United States and Canada have a long and rocky history of alternating between cooperating on joint management of Pacific salmon harvests and squabbling over their respective shares of the catch. The most recent breakdown in cooperation began in 1993, when the two nations became embroiled in an extended dispute that left them unable to agree on a full set of salmon "fishing regimes" under the terms of the Pacific Salmon Treaty. A new Agreement, signed on June 30, 1999, may end the conflict, but it is too early to judge its likelihood of success. The Canadians remain bitterly divided over the merits of the Agreement, which has been labeled a "sellout" by Canadian fishing interests, and the arrangement is still contingent on U.S. Congressional approval of $140 million for two jointly managed endowment funds to be used for scientific cooperation, stock enhancement and habitat restoration (Culbert and Beatty, 1999). The Agreement is also contingent on a U.S. Federal Government determination, by December 31,1999, that the Agreement satisfies the legal requirements of the Endangered Species Act (U.S. Department of State, 1999).
The recent acrimony began when northern salmon runs increased dramatically while southern runs declined, leading to a change in the overall balance of "interceptions " between the U.S. and Canada. These trends appear to be influenced by the effects of climatic variations on the ocean and stream environments, but climate is not the only source of harvest variability. Because it is difficult to disentangle natural and anthropogenic sources of variability, the negotiation process has been complicated by differences of opinion over the biological "facts". When marine survival rates for chinook and coho salmon originating in Washington, Oregon and British Columbia declined sharply during the early 1990s, the Parties proved unable to quickly and effectively constrain harvests (PSC-JCTC, 1994; PSC, 1995; 1996; Confederated Tribes and Bands v. Baldridge [W.D. Wash. September 7, 1995]). This almost certainly contributed to the current imperiled state of some of these stocks, culminating in recent listings of some Columbia Basin and Puget Sound chinook stocks under the Endangered Species Act (Shaffer, 1998; Whitman, 1999).
The complex role of an extended climatic regime-shift (Hare and Francis, 1995; Mantua et al., 1997) in this dispute suggests that future efforts to adapt to greenhouse gas-induced climate change may encounter analogous pitfalls. A better understanding of the role of unanticipated climatic trends or shifts in current resource-management disputes may help to smooth the path of adaptation, for example, by encouraging the development of more flexible allocation rules. Accordingly, this paper has two goals. The first is to summarize the nature of the possible impacts of anthropogenic climate change on Pacific salmon. The second is to draw lessons from the Treaty dispute regarding the process of adaptation in the case of transboundary fishery resources.
FIRST PARAGRAPH: Both the natural variability of the hydrologic cycle and potential disruptions of that cycle resulting from possible climate change can affect water supply and thus water management in the western United States. Uncertainty about both types of change poses a challenge for water resource managers. At the request of the Bureau of Reclamation, a committee of the Water Science and Technology Board convened a colloquium on November 14–16, 1990, to draw together material on climate change and climate variability and to explore possible water management responses. This proceedings contains an overview of that colloquium, ''Managing Water Resources in the West Under Conditions of Climate Uncertainty,'' and the individual papers presented there.
ABSTRACT: The restricted definition of “climate change” used by the Framework Convention on Climate Change (FCCC) has profoundly affected the science, politics, and policy processes associated with the international response to the climate issue. Specifically, the FCCC definition has contributed to the gridlock and ineffectiveness of the global response to the challenge of climate change. This paper argues that the consequences of misdefining “climate change” create a bias against adaptation policies and set the stage for the politicization of climate science. The paper discusses options for bringing science, policy and politics in line with a more appropriate definition of climate change such as the more comprehensive perspective used by the Intergovernmental Panel on Climate Change.
S. P. Prisley, M. J. Mortimer (2004). A synthesis of literature on evaluation of models for policy applications, with implications for forest carbon accounting. Forest Ecology and Management 198 (1-3): 89-103
ABSTRACT: Forest modeling has moved beyond the realm of scientific discovery into the policy arena. The example that motivates this review is the application of models for forest carbon accounting. As negotiations determine the terms under which forest carbon will be accounted, reported, and potentially traded, guidelines and standards are being developed to ensure consistency, accuracy, transparency and verifiability. To date, these guidelines have focused on definitions, data, and reporting, not models. The goal of this paper is to synthesize literature that may inform the development of guidelines for the application of models in areas with policy implications, such as forest carbon accounting. We discuss validation, verification, and evaluation as applied to modeling, and review common components of model evaluation. Peer review, quantitative analysis of model results, and sensitivity analysis are the most widely used approaches to model evaluation. US judicial and legislative perspectives on criteria for model acceptability are summarized.
ABSTRACT: Terrestrial carbon sinks and sources were introduced into climate change mitigation related policy relatively late in the design of the architecture of those policies. Much literature addresses how terrestrial sources and sinks differ from emissions from fossil fuel combustion and, hence, is a possible justification for differential treatment of them in policy design. Late introduction in climate policy discussions and perceived differences appear to have resulted in very different policy approaches for sinks versus fossil emission sources. The attempt to differentiate has generated complexity in policy design and likely inefficiency in the operation of these policies. We review these issues and find that the characteristics claimed to apply to sinks apply as well to fossil sources, and differences that do exist are often more a matter of degree than of kind. Because cap-and-trade has gained momentum as the instrument of choice to control fossil emissions, we use as a starting point, how such a cap-and-trade system could be altered to include terrestrial carbon sinks and sources.
ABSTRACT: This article analyzes how U.S. climate change politics and policy making are changing in the public, private and civil society sectors, and how such changes are likely to influence U.S. federal policies. It outlines the current status of U.S. climate change action and explores four overlapping pathways of policy change: (1) the strategic demonstration of the feasibility of climate change action; (2) the creation and expansion of markets; (3) policy diffusion and learning; and (4) the creation and promulgation of norms about the need for more aggressive climate change action. These four pathways seek to fruitfully draw from rationalist and constructivist approaches to policy analysis, without collapsing or confusing the different logics. Building on this analysis, it predicts that future federal U.S. climate policy will include six major components: (1) A national cap on GHG emissions; (2) A national market based cap-and-trade GHG emissions trading scheme; (3) Mandatory renewable energy portfolio standards; (4) Increased national product standards for energy efficiency; (5) Increased vehicle fleet energy efficiency standards; and (6) Increased federal incentives for research and development on energy efficiency issues and renewable energy development. In addition, expanding federal climate policy may bring about significant changes in U.S. foreign policy as U.S. international re-engagement on climate change is likely to occur only after the development of more significant federal policy.
ABSTRACT: Having risen from relative obscurity as few as ten years ago, climate change now looms large among environmental policy issues. Its scope is global; the potential environmental and economic impacts are ubiquitous; the potential restrictions on human choices touch the most basic goals of people in all nations; and the sheer scope of the potential response ? a significant shift away from using fossil fuels as the primary energy source in the modern economy ? is daunting. In this paper, we explore the economics of climate change policy. We examine the risks that climate change poses for society, the benefits of protection against the effects of climate change, and the costs of alternative protection policies. We organize our discussion around three broad themes: why costs and benefits matter in assessing climate change policies, as does the uncertainty surrounding them; why well-designed, cost-effective climate policies are essential in addressing the threat of climate change; and why a coherent architecture of international agreements is key to successful policy implementation. We conclude the paper with a summary of key policy lessons and gaps in knowledge.
ABSTRACT; Many countries are preparing national climate change action plans that describe specific measures they are taking to mitigate greenhouse gas emissions and adapt to the potential effects of climate change. Among the reasons for preparing such plans are that climate change is likely to occur, and many anticipatory measures that would be taken in response to climate change are no regret measures that will produce benefits even if climate does not change. Additionally, these plans can serve as communications required by the U.N. Framework Convention on Climate Change. We propose here an assessment process for anticipatory adaptation measures that will enable countries to identify and select measures to adapt to climate change. These measures anticipate potential climate changes and are flexible enough to meet objectives under a wide variety of future climate conditions. The process builds on assessments of vulnerability by focusing on adaptation measures for the most sensitive regions, or populations, within a country. Potential anticipatory adaptation measures are identified, and two or three are chosen based on expert judgment and analysis regarding which measures would produce the greatest benefits and be easiest to implement. Analytic techniques are used to assess the benefits and costs of each of the measures and evaluate barriers to implementation. The measure that is most cost-effective and is easiest to implement is selected. We illustrate the application of the process by examining a hypothetical forest threatened by climate change.
FIRST PARAGRAPH: When and if the United States decides on mandatory policies to address global climate change, it will be necessary to decide whether carbon sequestration should be part of the domestic portfolio of compliance activities. The potential costs of carbon sequestration policies will presumably be a major criterion, so it is important to assess the cost of supplying forest-based carbon sequestration in the United States. In this report we survey major studies, examine the factors that have affected their carbon sequestration cost estimates, and synthesize the results.
Thompson, R.S., S.W. Hostetler, P.J. Bartlein, K.H. Anderson (1998). A strategy for assessing potential future changes in climate, hydrology, and vegetation in the western United States. U.S. Department of the Interior, U.S. Geological Survey: 20 pp.
ABSTRACT: Historical and geological data indicate that significant changes can occur in the Earth's climate on time scales ranging from years to millennia. In addition to natural climatic change, climatic changes may occur in the near future due to increased concentrations of carbon dioxide and other trace gases in the atmosphere that are the result of human activities. International research efforts using atmospheric general circulation models (AGCM's) to assess potential climatic conditions under atmospheric carbon dioxide concentrations of twice the pre-industrial level (a "2 X CO2 " atmosphere) conclude that climate would warm on a global basis. However, it is difficult to assess how the projected warmer climatic conditions would be distributed on a regional scale and what the effects of such warming would be on the landscape, especially for temperate mountainous regions such as the Western United States. In this report, we present a strategy to assess the regional sensitivity to global climatic change. The strategy makes use of a hierarchy of models ranging from an AGCM, to a regional climate model, to landscape-scale process models of hydrology and vegetation. A 2 X CO2 global climate simulation conducted with the National Center for Atmospheric Research (NCAR) GENESIS AGCM on a grid of approximately 4.5o of latitude by 7.5o of longitude was used to drive the NCAR regional climate model (RegCM) over the Western United States on a grid of 60 km by 60 km. The output from the RegCM is used directly (for hydrologic models) or interpolated onto a 15-km grid (for vegetation models) to quantify possible future environmental conditions on a spatial scale relevant to policy makers and land managers.
U.S. Global Change Research Group, (2000). Climate change impacts on the United States: The potential consequences of climate variability and change. National Assessment Synthesis Team, U.S. Global Change Research Program
ABOUT THIS DOCUMENT: What is this Assessment? The National Assessment of the Potential Consequences of Climate Variability and Change is a landmark in the major ongoing effort to understand what climate change means for the US. Climate science is developing rapidly and scientists are increasingly able to project some changes at the regional scale, identifying regional vulnerabilities, and assessing potential regional impacts. Science increasingly indicates that the Earth's climate has changed in the past and continues to change, and that even greater climate change is very likely in the 21st century. This Assessment has begun a national process of research, analysis, and dialogue about the coming changes in climate, their impacts, and what Americans can do to adapt to an uncertain and continuously changing climate. This Assessment is built on a solid foundation of science conducted as part of the United States Global Change Research Program (USGCRP).
What is this document and who is the NAST? This document is the Assessment Overview, written by the National Assessment Synthesis Team (NAST). The NAST is a committee of experts drawn from governments, universities, industry, and non-governmental organizations. It has been responsible for broad over-sight of the Assessment, with the Federal agencies of the USGCRP. This Overview is based on a longer, referenced "Foundation" report, written by the NAST in cooperation with independent regional and sector assessment teams. These two national-level, peer-reviewed documents synthesize results from studies conducted by regional and sector teams, and from the broader scientific literature.
Why was this Assessment undertaken? The Assessment was called for by a 1990 law, and has been con-ducted under the USGCRP in response to a request from the President's Science Advisor. The NAST developed the Assessment's plan, which was then approved by the National Science and Technology Council, the cabinet-level body of agencies responsible for scientific research, including global change research, in the US government.
D. P. Van Vuuren, M. Meinshausen, G.-K. Plattner, F. Joos, K. M. Strassmann, S. J. Smith, T. M. L. Wigley, S. C. B. Raper, K. Riahi, F. de la Chesnaye, M. G. J. den Elzen, J. Fujino, K. Jiang, N. Nakicenovic, S. Paltsev, J. M. Reilly (2008). Temperature increase of 21st century mitigation scenarios. Proceedings of the National Academy of Sciences 105 (40): 15258-15262
ABSTRACT: Estimates of 21st Century global-mean surface temperature increase have generally been based on scenarios that do not include climate policies. Newly developed multigas mitigation scenarios, based on a wide range of modeling approaches and socioeconomic assumptions, now allow the assessment of possible impacts of climate policies on projected warming ranges. This article assesses the atmospheric CO2 concentrations, radiative forcing, and temperature increase for these new scenarios using two reduced-complexity climate models. These scenarios result in temperature increase of 0.5–4.4°C over 1990 levels or 0.3–3.4°C less than the no-policy cases. The range results from differences in the assumed stringency of climate policy and uncertainty in our understanding of the climate system. Notably, an average minimum warming of ≈1.4°C (with a full range of 0.5–2.8°C) remains for even the most stringent stabilization scenarios analyzed here. This value is substantially above previously estimated committed warming based on climate system inertia alone. The results show that, although ambitious mitigation efforts can significantly reduce global warming, adaptation measures will be needed in addition to mitigation to reduce the impact of the residual warming.
ABSTRACT: The ultimate goal of the UN Framework Convention on Climate Change is to achieve "stabilization of greenhouse-gas concentrations at a level that would prevent dangerous anthropogenic interference with the climate system". With the concentration targets yet to be determined, Working Group I of the Intergovernmental Panel on Climate Change developed a set of illustrative pathways for stabilizing the atmospheric CO2 concentration at 350, 450, 550, 650 and 750 p.p.m.v. over the next few hundred years1,2 . But no attempt was made to determine whether the implied emissions might constitute a realistic transition away from the current heavy dependence on fossil fuels. Here we devise new stabilization profiles that explicitly (albeit qualitatively) incorporate considerations of the global economic system, estimate the corresponding anthropogenic emissions requirements, and assess the significance of the profiles in terms of global-mean temperature and sea level changes. Our findings raise a number of important issues for those engaged in climate-change policy making, particularly with regard to the optimal timing of mitigation measures.