'Third National Climate Assessment: Climate Change Impacts in the United States' released

May 6, 2014
Washington, D.C.
(This pages includes excerpts from globalchange.gov and NCA communications.)
The Third National Climate Assessment (NCA) was released by the White House on May 6, 2014. The assessment delivers on USGCRP’s legal mandate and the President’s Climate Action Plan, is 'the most comprehensive, authoritative, transparent scientific report ever generated on U.S. climate impacts, both as currently observed and as projected for the future'. The Third NCA documents climate change-related impacts and responses across key sectors and all regions of the U.S. with the goal of better informing public and private decision-making at all levels.

Carbon Cycle in the Third NCA

The U.S. Carbon Cycle Science Program/CCIWG provided technical input to the Third NCA via eight commissioned research papers that culminated into a special open access issue of the Ecological Society of America's Frontiers in Ecology on 'Biogenic Greenhouse Gases in North American Terrestrial Ecosystems'. These studies (Post and Venterea, 2013) found that:
  • Approximately 35% of fossil-fuel-derived CO2 emissions in North America are currently absorbed by terrestrial ecosystems;
  • Biogenic CH4 and N2O emissions offset at least half of this terrestrial COuptake; and
  • Full accounting of related costs and benefits shows that improved management of agricultural and forest ecosystems can economically mitigate atmospheric greenhouse gas concentrations in the next decades . 

The Third NCA's Biogeochemical Cycles Chapter highlights the above findings. (Also see adjoining figure from NCA, 2014.) More information on the carbon cycle can be found here



The Third NCA's Mitigation Chapter as well as other chapters/sections also address the carbon cycle. According to the key messages in the Mitigation Chapter:
'Carbon dioxide is removed from the atmosphere by natural processes at a rate that is roughly half of the current rate of emissions from human activities. Therefore, mitigation efforts that only stabilize global emissions will not reduce atmospheric concentrations of carbon dioxide, but will only limit their rate of increase. The same is true for other long-lived greenhouse gases.To meet the lower emissions scenario (B1) used in this assessment, global mitigation actions would need to limit global carbon dioxide emissions to a peak of around 44 billion tons per year within the next 25 years and decline thereafter. In 2011, global emissions were around 34 billion tons, and have been rising by about 0.9 billion tons per year for the past decade. Therefore, the world is on a path to exceed 44 billion tons per year within a decade.Over recent decades, the U.S. economy has emitted a decreasing amount of carbon dioxide per dollar of gross domestic product. Between 2008 and 2012, there was also a decline in the total amount of carbon dioxide emitted annually from energy use in the United States as a result of a variety of factors, including changes in the economy, the development of new energy production technologies, and various government policies.Carbon storage in land ecosystems, especially forests, has offset around 17% of annual U.S. fossil fuel emissions of greenhouse gases over the past several decades, but this carbon “sink” may not be sustainable. Both voluntary activities and a variety of policies and measures that lower emissions are currently in place at federal, state, and local levels in the United States, even though there is no comprehensive national climate legislation. Over the remainder of this century, aggressive and sustained greenhouse gas emission reductions by the United States and by other nations would be needed to reduce global emissions to a level consistent with the lower scenario (B1) analyzed in this assessment.'
Third NCA Print Materials Request Form 

The 830-page Full Report will not be available in print; however, printed copies of a 140-page Highlights summary report and a 20-page Overview booklet will be available in the next several weeks. Please note that the content of the 20-page Overview booklet is included in the beginning of the 140-page Highlights summary report. These can be mailed toyou free of charge. Requests for multiple copies can be accommodated, but may be limited by availability. The request form can be found here: http://tinyurl.com/nca3-orders



 Digital PDF Downloads
Low- and high-resolution PDFs of the 830-page Full Report in a single file, its individual sections, the 140-page Highlights summary report, and the 20-page Overview booklet are each available for immediate digital download here: http://nca2014.globalchange.gov/downloads
Additional PDF materials including a 4-page Report Findings brochure, a 4-page Climate Trends and Regional Impacts brochure, and 2-page summaries for the Northeast, Southeast and Caribbean, Midwest, Great Plains, Southwest, Northwest, Alaska, Hawaii and U.S. Affiliated Pacific Islands, and the Agriculture sector can be downloaded here: http://www.globalchange.gov/nca3-downloads-materials

The Third NCA is available to download and also can be explored in a novel interactive format through USGCRP’s newly redeployed web presence at http://globalchange.gov. An important feature of this interactivity is the traceability of the data and other information in the report, giving users the means to refer back to these data for their analyses and decision support. The site is mobile-compatible and every piece of the report—from highlights to chapters to key messages to graphics—has its own unique URL for social network sharing. Please find below links that will help you navigate the Third NCA:
Beyond the Third NCA, the new globalchange.gov features accessible and dynamic information on a wide range of climate-related topics.
White House materials about the release of the Third NCA are available from: http://www.whitehouse.gov/climate-change

(Source: NCA 2014, USGCRP and National Climate Assessment staff)

The data and information in the Third NCA can be of great value to the adaptation planning and implementation efforts of U.S. Federal Agencies and their partners and stakeholders. Some examples include: 
  • The latest science on observed trends and projected future conditions of changes in the climate across the 8 NCA regions and contiguous U.S. as well as 13 sectors and cross-sectors. 
  • Examples throughout of on-the-ground impacts across the U.S., many of which are already directly affecting substantial numbers of Americans.
  • For the first time in a U.S. national assessment, explicit chapters on Decision Support, Mitigation, and Adaptation, with specific information on those topics as they are practiced now in addition to identifying research needs associated with these topics for improving future implementation of climate resilience measures. Specifically related to adaptation, the following information is captured in the Adaptation chapter:
    • Adaptation key terms defined
    • An overview of adaptation activities at multiple levels including the Federal government, states, tribes, local and regional governments, non-governmental organizations, and the private sector
    • Example barriers to adaptation
    • Several illustrative case studies of adaptation in action
  • A useful and informative section that answers some frequently asked questions about climate change. The questions addressed range from those purely related to the science of climate change to those that extend to some of the issues being faced in consideration of mitigation and adaptation measures. 
  • Data and metadata behind content and images used in the assessment are accessible and traceable. 


Below are the very high level talking about about the Third NCA. 
  • Climate change is not just a problem for the future - it has moved firmly into the present. Observed climate changes across the United States and within its major regions over the past century are extensively documented in the Third NCA. The Assessment links these climate changes to impacts on the American people and on the environment in every region of our country.
  • Many Americans are already feeling the effects of increases in certain types of extreme weather and sea level rise that are fueled by climate change. Prolonged periods of heat and heavy downpours, and in some regions, drought, are affecting our health, agriculture, water resources, energy and transportation infrastructure, and much more. Rising sea level and higher storm surges are putting people and property at risk.
  • This Assessment is the most comprehensive analysis to date of how climate change is affecting our nation now and could affect it in the future. The Assessment helps inform Americans’ choices and decisions about investments, where to build and where to live, how to create safer communities and secure our own and our children's future.
  • America has important opportunities to reduce emissions and prepare for the effects of climate change. Large reductions in global emissions could avoid some of the damaging impacts of climate change. Just as importantly, communities that prepare for the range of climate change impacts can prevent needless harm.
See the NCAnet Partners Calendar (http://ncanet.usgcrp.gov/partners/calendar).