Climate Change and...
Effects of Climate Change
Social, Cultural, and Economic Dimensions
- Climate Variability
- Climate Models
Effects of Climate Change
ABSTRACT: Abstract: Purpose – The purpose of this paper is to identify and describe key economic and policy-related issues with regard to terrestrial C sequestration and provide an overview of the economics of C sequestration on agricultural soils in the USA.
Design/methodology/approach – Recent economic literature on carbon sequestration was reviewed to gather insights on the role of agriculture in greenhouse gas emissions mitigation. Results from the most salient studies were presented in an attempt to highlight the general consensus on producer-level responses to C sequestration incentives and the likely mechanisms used to facilitate C sequestration activities on agricultural soils.
Findings – The likely economic potential of agriculture to store soil C appears to be considerably less than the technical potential. Terrestrial C sequestration is a readily implementable option for mitigating greenhouse gas emissions and can provide mitigation comparable in cost to current abatement options in other industries. Despite considerable research to date, many aspects of terrestrial C sequestration in the USA are not well understood.
Originality/value – The paper provides a useful synopsis of the terms and issues associated with C sequestration, and serves as an informative reference on the economics of C sequestration that will be useful as the USA debates future greenhouse gas emissions mitigation policies.
ABSTRACT: A multiperiod, regional, mathematical programming model is used to evaluate the potential economic impacts of global climatic change scenarios on the US forest and agricultural sectors, including impacts on forest carbon inventories. Four scenarios of the biological response of forests to climate change (reflected by changes in forest growth rates) are drawn from a national assessment of climate change and are based on combinations of global circulation and ecological process models. These scenarios are simulated in tile the forest and agricultural sector model and results are summarized to characterize broad impacts of climate change on the sectors. We find that less cropland is projected to be converted to forests, forest inventories generally increase, and that aggregate economic impacts (across all consumers and producers in the sector) are relatively small. Producers’ income is most at risk, and impacts of global climate change on the two sectors vary over the 100-year projection period. The forest sector is found to have adjustment mechanisms that mitigate climate change impacts, including interregional migration of production, substitution in consumption, and altered stand management.
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, 126.96.36.199 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.
P. Smith, D. S. Powlson, J. U. Smith, P. Falloon, K. Coleman (2000). Meeting Europe's climate change commitments: quantitative estimates of the potential for carbon mitigation by agriculture. Global Change Biology 6 (5): 525-539
ABSTRACT: Under the Kyoto Protocol, the European Union is committed to a reduction in CO2 emissions to 92% of baseline (1990) levels during the first commitment period (2008–2012). The Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere. Thus, land-use/land-management change and forestry activities that are shown to reduce atmospheric CO2 levels can be included in the Kyoto targets. These activities include afforestation, reforestation and deforestation (article 3.3 of the Kyoto Protocol) and the improved management of agricultural soils (article 3.4). In this paper, we estimate the carbon mitigation potential of various agricultural land-management strategies and examine the consequences of European policy options on carbon mitigation potential, by examining combinations of changes in agricultural land-use/land-management.
We show that no single land-management change in isolation can mitigate all of the carbon needed to meet Europe's climate change commitments, but integrated combinations of land-management strategies show considerable potential for carbon mitigation. Three of the combined scenarios, one of which is an optimal realistic scenario, are by themselves able to meet Europe's emission limitation or reduction commitments.
Through combined land-management scenarios, we show that the most important resource for carbon mitigation in agriculture is the surplus arable land. We conclude that in order to fully exploit the potential of arable land for carbon mitigation, policies will need to be implemented to allow surplus arable land to be put into alternative long-term land-use.
Of all options examined, bioenergy crops show the greatest potential for carbon mitigation. Bioenergy crop production also shows an indefinite mitigation potential compared to other options where the mitigation potential is finite. We suggest that in order to exploit fully the bioenergy option, the infrastructure for bioenergy production needs to be significantly enhanced before the beginning of the first Kyoto commitment period in 2008.
It is not expected that Europe will attempt to meet its climate change commitments solely through changes in agricultural land-use. A reduction in CO2 -carbon emissions will be key to meeting Europe's Kyoto targets, and forestry activities (Kyoto Article 3.3) will play a major role. In this study, however, we demonstrate the considerable potential of changes in agricultural land-use and -management (Kyoto Article 3.4) for carbon mitigation and highlight the policies needed to promote these agricultural activities. As all sources of carbon mitigation will be important in meeting Europe's climate change commitments, agricultural carbon mitigation options should be taken very seriously.
ABSTRACT: The world’s climate is changing and will continue to change into the coming century at rates projected to be unprecedented in recent human history. The risks associated with these changes are real but highly uncertain. Societal vulnerability to the risks associated with climate change may exacerbate ongoing social and economic challenges, particularly for those parts of societies dependent on resources that are sensitive to changes in climate. Risks are apparent in agriculture, fisheries and many other components that constitute the livelihood of rural populations in developing countries. In this paper we explore the nature of risk and vulnerability in the context of climate change and review the evidence on present-day adaptation in developing countries and on coordinated international action on future adaptation. We argue that all societies are fundamentally adaptive and there are many situations in the past where societies have adapted to changes in climate and to similar risks. But some sectors are more sensitive and some groups in society more vulnerable to the risks posed by climate change than others. Yet all societies need to enhance their adaptive capacity to face both present and future climate change outside their experienced coping range. The challenges of climate change for development are in the present. Observed climate change, present-day climate variability and future expectations of change are changing the course of development strategies - development agencies and governments are now planning for this adaptation challenge. The primary challenge, therefore, posed at both the scale of local natural resource management and at the scale of international agreements and actions, is to promote adaptive capacity in the context of competing sustainable development objectives.
ABSTRACT: The frequent warnings that global climate change will allow falciparum malaria to spread into northern latitudes, including Europe and large parts of the United States, are based on biological transmission models driven principally by temperature. These models were assessed for their value in predicting present, and therefore future, malaria distribution. In an alternative statistical approach, the recorded present-day global distribution offalciparum malaria was used to establish the current multivariate climatic constraints. These results were applied to future climate scenarios to predict future distributions, which showed remarkably few changes, even under the most extreme scenarios.
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: 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.
Vitousek, P.M., J. Aber, R. Howarth, G.E. Likens, P. Matson, D. Schindler, W. Schlesinger, G.D. Tilman (1997). Human alteration of the global nitrogen cycle: causes and consequences. Ecological Applications 7 (3): 737-750
ABSTRACT: Nitrogen is a key element controlling the species composition, diversity, dynamics, and functioning of many terrestrial, freshwater, and marine ecosystems. Many of the original plant species living in these ecosystems are adapted to, and function optimally in, soils and solutions with low levels of available nitrogen. The growth and dynamics of herbivore populations, and ultimately those of their predators, also are affected by N. Agriculture, combustion of fossil fuels, and other human activities have altered the global cycle of N substantially, generally increasing both the availability and the mobility of N over large regions of Earth. The mobility of N means that while most deliberate applications of N occur locally, their influence spreads regionally and even globally. Moreover, many of the mobile forms of N themselves have environmental consequences. Although most nitrogen inputs serve human needs such as agricultural production, their environmental consequences are serious and long term.
Based on our review of available scientific evidence, we are certain that human alterations of the nitrogen cycle have:
1. approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing;
2. increased concentrations of the potent greenhouse gas N2 O globally, and increased concentrations of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth;
3. caused losses of soil nutrients, such as calcium and potassium, that are essential for the long-term maintenance of soil fertility;
4. contributed substantially to the acidification of soils, streams, and lakes in several regions; and
5. greatly increased the transfer of nitrogen through rivers to estuaries and coastal oceans.
In addition, based on our review of available scientific evidence we are confident that human alterations of the nitrogen cycle have:
1. increased the quantity of organic carbon stored within terrestrial ecosystems;
2. accelerated losses of biological diversity, especially losses of plants adapted to efficient use of nitrogen, and losses of the animals and microorganisms that depend on them; and
3. caused changes in the composition and functioning of estuarine and nearshore ecosystems, and contributed to long-term declines in coastal marine fisheries.
ABSTRACT: Climate models suggest that global warming could bring warmer, drier conditions to Mexico. Although precipitation increases are projected by some models, in most cases they do not compensate for increases in potential evaporation. Thus, soil moisture and water availability may decrease over much of Mexico with serious consequences for rainfed and irrigated agriculture, urban and industrial water supplies, hydropower and ecosystems. However, the assessment of global warming impacts in Mexico is an uncertain task because the projections of different models vary widely, particularly for precipitation, and because they perform poorly in reproducing the observed climate of Mexico.
ABSTRACT: Fire was arguably the most important forest and rangeland disturbance process in the Inland Northwest United States for millennia. Prior to the Lewis and Clark expedition, fire regimes ranged from high severity with return intervals of one to five centuries, to low severity with fire-free periods lasting three decades or less. Indoamerican burning contributed to the fire ecology of grasslands and lower and mid-montane dry forests, especially where ponderosa pine was the dominant overstory species, but the extent of this contribution is difficult to quantify. Two centuries of settlement, exploitation, management, and climate variation have transformed the fire regimes, vegetation and fuel patterns, and overall functionality of these forests. We present a narrative that portrays conditions beginning at the first contact of Euro-American settlers with Indoamericans of the region and extending to the present. Due in part to its geographic isolation, the Inland Northwest was among the last regions to be discovered by Euro-Americans. In 200 years the region has undergone fur trapping and trading, sheep, cattle, and horse grazing, timber harvesting, mining, road construction, native grassland conversion to agricultural production, urban and rural area development, fire prevention, and fire suppression. We highlight key changes to forest landscape patterns and processes that occurred under these combined influences, discuss implications of the changes, and progress towards restoring sustainability. An adaptive ecosystem management model has been adopted by public land management agencies to remedy current conditions. Ecosystem management is a relatively new concept that emphasizes the integrity and sustainability of land systems rather than outputs from the land. Adaptive management emphasizes the twin notions that incomplete knowledge and high degrees of risk and uncertainty about earth and climate systems will always limit land and resource planning and management decisions, and that management is chiefly a learning and adapting process. We discuss current issues and future options associated with ecosystem management, including the low likelihood of social consensus concerning desired outcomes, the lack of integrated planning, analysis, and decision support tools, and mismatches between existing land management planning processes, Congressional appropriations, and complex management and restoration problems.
DESCRIPTION: Various human groups have greatly affected the processes and evolution of Middle Rio Grande Basin ecosystems, especially riparian zones, from A.D. 1540 to the present. Overgrazing, clear-cutting, irrigation farming, fire suppression, intensive hunting, and introduction of exotic plants have combined with droughts and floods to bring about environmental and associated cultural changes in the Basin. As a result of these changes, public laws were passed and agencies created to rectify or mitigate various environmental problems in the region. Although restoration and remedial programs have improved the overall "health" of Basin ecosystems, most old and new environmental problems persist.
ABSTRACT: A large assemblage of salmon bones excavated 50 yr ago from an ~10,000-yr-old archaeological site near The Dalles, Oregon, USA, has been the primary evidence that early native people along the Columbia River subsisted on salmon. Recent debate about the human role in creating the deposit prompted excavation of additional deposits and analysis of archaeologic, geologic, and hydrologic conditions at the site. Results indicate an anthropogenic source for most of the salmonid remains, which have associated radiocarbon dates indicating that the site was occupied as long ago as 9300 cal yr B.P. The abundance of salmon bone indicates that salmon was a major food item and suggests that migratory salmonids had well-established spawning populations in some parts of the Columbia Basin by 9300–8200 yr ago.
ABSTRACT: Modern complex societies exhibit marked resilience to interannual-to- decadal droughts, but cultural responses to multidecadal-to-multicentury droughts can only be addressed by integrating detailed archaeological and paleoclimatic records. Four case studies drawn from New and Old World civilizations document societal responses to prolonged drought, including population dislocations, urban abandonment, and state collapse. Further study of past cultural adaptations to persistent climate change may provide valuable perspective on possible responses of modern societies to future climate change.
ABSTRACT: Recent studies have yielded definitive information about the nation's economic impacts from extreme climates, although some sectoral values rely on educated estimates since hard data does not exist. Review of existing measures of the national impacts from weather–climate conditions reveals annual average losses of $36 billion from extremes and gains averaging $26 billion when conditions are favorable (good growing seasons, mild winters, etc.). Comparison of these values with various measures of the national economy reveals that the impacts are relatively small, typically about 1% of the Gross Domestic Product and less than 2% of the federal budget. The current impact information provides a basis for assessing various estimates of the nation's financial impacts resulting from a future climate change due to global warming. Most such estimates predict values similar to the magnitude of current climate impacts. Moreover, most economists attempting such estimates express a large degree of uncertainty about their projections.
FIRST PARAGRAPH(s): Global climate change, which might be anticipated as a result of increased atmospheric concentrations of CO2 and other trace gases (i.e. "greenhouse effect") has received considerable attention in recent years from the scientific (Kellogg 1987) and policy-oriented (Schneider 1989) communities.
Atmospheric concentrations of CO2 have increased by more than 25% since the Industrial Revolution began in the nineteenth century. Concentrations of other greenhouse gases (e.g. CH4 ) have also increased. At the same time, global temperature has risen by about 0.5°C (after accounting for urban effects on station data [Jones et al. 1989; Karl and Jones 1989]). Whether this is evidence of the arrival of an anthropogenically enhanced greenhouse effect is a subject of considerable debate, but there is a consensus that a much larger climatic warming is highly probable within the next few decades.
ABSTRACT: Land-use change is related to climate change as both a causal factor and a major way in which the effects of climate change are expressed. As a causal factor, land use influences the flux of mass and energy, and as land-cover patterns change, these fluxes are altered. Projected climate alterations will produce changes in land-cover patterns at a variety of temporal and spatial scales, although human uses of the land are expected to override many effects. A review of the literature dealing with the relationship between land-use change and climate change clearly shows that (1) in recent centuries land-use change has had much greater effects on ecological variables than has climate change; (2) the vast majority of land-use changes have little to do with climate change or even climate; and (3) humans will change land use, and especially land management, to adjust to climate change and these adaptations will have some ecological effects. Therefore, an understanding of the nonclimatic causes of land-use change (e.g., socioeconomics and politics) are necessary to manage ecological functions effectively on regional and global scales.
Parson, E. A., National Assessment Synthesis Team; U.S. Global Change Research Program, (2001). Potential consequences of climate variability and change for the Pacific Northwest. Cambridge University Press: Chapter 9
SUMMARY: The Northwest, which includes the states of Washington, Oregon, and Idaho, has a great diversity of resources and ecosystems, including spectacular forests containing some of the world’s largest trees; abrupt topography that generates sharp changes in climate and ecosystems over short distances; mountain and marine environments in close proximity, making for strong reciprocal influences between terrestrial and aquatic environments; and nearly all the volcanoes and glaciers in the contiguous US. The region has seen several decades of rapid population and economic growth, with population nearly doubling since 1970, a growth rate almost twice the national average. The same environmental attractions that draw people and investment to the region are increasingly stressed by the region’s rapid development. The consequences include loss of old growth forests, wetlands, and native grass and steppe communities, increasing urban air pollution, extreme reduction of salmon runs, and increasing numbers of threatened and endangered species. Climate change and its impacts will interact with these existing stresses in the region.
Mote, P. W., D. J. Canning, D. L. Fluharty, R.C. Francis, J. F. Franklin, A. F. Hamlet, M. Hershman, M. Holmberg, K. N. Ideker, W. S. Keeton, D. P. Lettenmaier, L. R. Leung, N. J. Mantua, E. L. Miles, B. Noble, H. Parandvash, D. W. Peterson, A. K. Snover, S. R. Willard (1999). Impacts of climate variability and change, Pacific Northwest. National Atmospheric and Oceanic Administration, Office of Global Programs, and JISAO/SMA Climate Impacts Group: 110 pp.
OVERVIEW: Experience of the recent past illustrates the impacts that the climate variations have on the Pacific Northwest, and illustrates that there are both winners and loser when the climate is different from the “average.” The mild winter and spring of 1997—98 saw an early snow melt, which strained regional water supplies during the summer and fall months. An especially warm and dry summer, coupled with the early melt, led to exceptionally low flows and high temperatures in many Northwest streams. These conditions in turn caused severe difficulties for salmon. However, 1997—98 also had benefits for the region, which avoided the damage and disruption caused by heavy snow fall and winter flooding during the previous two winters.
Climate is not a constant, and yet many aspects of human infrastructure and activities are planned with the assumption that it is constant. But what happens when climate produces a surprise? What if, furthermore, there are long-term changes in climate? Humans have altered the composition of Earth’s atmosphere to such an extent that climate itself appears to be changing. The consequences of a changing climate may be beneficial for some places and activities, and detrimental for others.
This report describes the possible impacts of human-induced climate change and of natural climate variability like El Niño, focusing on the water resources, salmon, forests, and coasts of the Pacific Northwest (PNW). It has been prepared largely by the Climate Impacts Group (CIG) at the University of Washington. The CIG, under the direction of Professor Edward L. Miles, is an interdisciplinary group of researchers from the physical, biological, and social sciences working together to understand the impacts of climate variability and change on the Northwest.
Looking at the recent past, much of the climate history of the PNW can be described by a few recurring patterns. The strongest pattern highlights the tendency for winter climate to be either relatively cool and wet or relatively warm and dry. Cool-wet winters are generally associated with increased risks of flooding and landslides, abundant summer water supply, more abundant salmon, reduced risk of forest fires, and improved tree growth (except at high elevation). Warm-dry winters are often followed by summer water shortages, less abundant salmon, and increased risk of forest fires. The occurrence of the cool-wet or warm-dry winter pattern is influenced by two main climate variations in the Pacific Basin: ENSO (El Niño-Southern Oscillation) primarily on year-to-year timescales and PDO (the Pacific Decadal oscillation) primarily on decade-to-decade timescales. ENSO and PDO cause variation sin snowpack and streamflow, and hence the ability to meet water resource objectives; with respect tot he region’s water resources, ENSO and PDO can reinforce or cancel each other. In contrast, the response of forests and salmon is correlated more strongly with the PDO than with ENSO. The magnitude of seasonal anomalies of temperature and precipitation leading to the above effects is strikingly small, but these past anomalies enable us to calibrate the possible responses to long-term climate change.
Looking to the future, computer models of climate generally agree that the PNW will become, over the next half century, gradually warmer and wetter, with most of the precipitation increase in winter. These trends mostly agree with observed changes over the past century. Wetter winters would likely mean more flooding of certain rivers, and landslides on steep coastal bluffs. The region’s warm, dry summers may see slight increases in rainfall, according to the models, but the gains in rainfall will be more than offset by losses due to increases in evaporation. Loss of moderate-elevation snowpack in response to warmer winter temperatures would have enormous and mostly negative impacts on the region’s water resources, forests, and salmon. Among these impacts are a diminished ability to store water in reservoirs for summer use, more drought-stressed tress leading to reductions in forested area, and spawning and rearing difficulties for salmon.
Knowing what changes might occur is only part of the challenge, however. This knowledge must make its way from the realm of research to the realm of decisions, and be used in decisions. Large practical and, in some cases, legal constraints prevent climate information from being fully utilized. Meeting the challenges posed by climate variations and climate change will require considerable revision of the policies and practices concerning how the region’s natural resources are managed. An indication of the scope of such revisions comes from considering how government agencies have handled climate-related stresses in the past, like droughts and coastal erosion. In many cases, agencies cannot even make use of a good seasonal forecast in making short-term planning decision: the operating assumption is often that climate is constant and extremes do not occur. There are wide variations among the four sectors considered here in how management presently makes use of climate information.