“Global Climate Change Impacts in the United States” – Report Overview (Part 1 of a series)


Global Climate Change Impacts in the United States, a scientifically based assessment report issued on June 16 by the U.S. Global Change Research Program, with its focus on the likely impacts of climate change across the nation, has the potential to add a much-needed dimension to policy debates about the costs and benefits of mitigation and adaptation measures.  The potentially devastating impacts of climate change on all aspects of human life have all-too-often been missing from discussions of climate change policy, which has emphasized mitigation options to reduce emissions while neglecting the need for strategies for adaptation and preparedness to deal with impacts that are already in evidence and projected to be much more damaging in the future.  As the report authors note: “concerns about climate change impacts will almost certainly alter perceptions and valuations of energy technology alternatives.” (p. 54).

This is the first in a series on the report and issues it raises for the US level of preparedness for climate change consequences and impacts.

See our related posts:

US Climate Change Impacts Report Shows Immediate Need for Action – White House must lead in preparing

Video link and key quotes from White House briefing on Global Climate Change Impacts report

President Obama should lead in talking about the consequences of inaction on climate change

The US Global Change Research Program (USGCRP) has a brand new website, launched on June 16, 2009, the day of release of the impacts report:

U.S. Global Change Research Program

The impacts report is posted there, along with supporting materials:  Impacts report home page, with a link to download the full report (.pdf), and a 20-page highlights brochure

Meanwhile, the former USGCRP/CCSP website, containing the full set of 21 Synthesis and Assessment Products generated under the Bush administration and other relevant reports and materials, is still open and accessible.


Global Climate Change Impacts in the United States synthesizes information from a number of other publications, chiefly the 21 Synthesis and Assessment Products sponsored by the Climate Change Science Program* (CCSP), in an attempt to outline the state of knowledge about current and future impacts of global climate change on ecosystems and the human systems in the United States that depend on them.

As scientific consensus about the occurrence and anthropogenic origins of climate change has solidified, the focus of some climate research is beginning to shift.  Throughout its 20-year history, the federal climate research program has focused primarily on observing and modeling change in the physical climate system.  The program’s annual report for FY2009, Our Changing Planet, notes that as our understanding of the global climate system has sharpened, interest in the local and regional impacts of climate change is growing. These concerns are reflected in the program’s Goals 4 and 5, which aim to, respectively: understand the sensitivity and adaptability of different natural and managed ecosystems and human systems to climate and related global changes, and explore the uses and identify the limits of evolving knowledge to manage risks and opportunities related to climate variability and change.

Accordingly, the USGCRP climate change impacts report lays out current knowledge on the present and future impacts of climate change on US ecosystems, public health, and built environments.  The report does not advocate particular mitigation or adaptation strategies nor project the results of any particular policy solution; it rather presents the future implications of current and projected rates of greenhouse gas emissions under scenarios that employ varying assumptions about population, economic activity, choice of energy technologies, and other factors.

The report says these scenarios “cover a range of emissions of heat-trapping gases, and the associated climate projections illustrate that lower emissions result in less climate change and thus reduced impacts over this century and beyond.  Under all scenarios considered in this report, however, relatively large and sustained changes in many aspects of climate are projected by the middle of the century, with even larger changes by the end of this century, especially under higher emissions scenarios” (p. 10).

Although the existence and projected continuation of a global warming trend is well-supported, the impacts of climate change on smaller geographical scales are only roughly understood.  Due to a number of factors, including uncertainties about climate sensitivity to increasing greenhouse gas concentrations, positive climate feedback effects, and the impacts of climate change on ecosystems and the human-built environment, further studies on local and regional impacts are very much needed.  The USGCRP report makes this explicit in the “Agenda for Climate Impacts Science” section, noting that while “advancing our knowledge in the many aspects of science that affect the climate system has already contributed greatly to decision making on climate change issues,” the focus of their recommendations is on “advancing our knowledge specifically on climate change impacts and those aspects of climate change responsible for these impacts in order to continue to guide decision making” (p. 153).”

While the report makes the need for further studies of the local and regional impacts of climate change readily apparent, there is an equally pressing need for the development of an operational U.S. management infrastructure equipped to deal with the challenges posed to a range of human and natural systems by a rapidly changing climate.  (However, the USGCRP, as it is currently configured and managed, is not the appropriate entity to lead or to orchestrate such an operational infrastructure within the federal government; we will stipulate and defend, in future posts, the need for new White House leadership and indeed a new coordination body to take on this ambitious but essential role of government.)

“Adaptation” in this context is defined in one of the CCSP’s 21 Synthesis and Assessment Products (SAPs) as “adjustments in human social systems (e.g., management) in response to climate stimuli and their effects” (CCSP SAP 4.4, p. 1).  Another of the SAPs identifies two related decision-making/management strategies that may be especially useful in the face of high uncertainty: “resilient” strategies that “try to identify the range of future circumstances that one might face, and then seek to identify approaches that work reasonably well across that range,” and “adaptive” strategies that “can be modified to achieve better performance as one learns more about the issues at hand and how the future is unfolding.” (CCSP SAP 5.2; p. 115-116).

The authors of the recent USGCRP impacts report refer frequently to “decision makers” and their need to be supplied with information about the changing climate on multiple scales: “these effects are very likely to be relevant for energy policies, decisions, and institutions in the United States, affecting courses of action and appropriate strategies for risk management” (54).  But the gap between scientific information and policy with respect to climate change adaptation has yet to be bridged.  As decision makers and managers at all levels consider strategies of this nature, they will be better equipped to apprise both researchers and elected officials of the data and resources needed for local adaptive responses.  This should offer an opportunity to strengthen the partnership between research and management that is so crucial in addressing an unprecedented and constantly evolving challenge.

The report takes some important steps towards advancing a more holistic understanding of the challenges presented by a warming climate, emphasizing the interconnectedness of impacts on human and natural systems.

Subsequent posts in this series will highlight projected impacts at the regional level nationwide, as well as in several key socioeconomic sectors, and begin to examine a variety of issues relating to “planning and preparedness” in communities across the nation, and associated “adaptation” and “mitigation” responses at the local and regional level.

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* The U.S. Global Change Research Program (USGCRP) coordinates and integrates federal research on changes in the global environment and their implications for society. The USGCRP began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990 (P.L. 101-606), which called for “a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.” Thirteen departments and agencies participate in the USGCRP, which was known as the U.S. Climate Change Science Program (CCSP) from 2002 through 2008.

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