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U.S. National Climate Assessment Reports On The Science Of Climate Change And Its Impacts

By Bindu Bhakta

U.S. Global Change Research Program assessment presents many examples of how climate change is already affecting and will increasingly affect our lives in the future.

On May 6, 2014, the U.S. Global Change Program released The Third National Climate Assessment. This report reviews current and projected changes in climate, impacts of these changes on U.S. regions and sectors (such as agriculture, transportation, and public health), and options for responding. The goal of the Assessment is to better inform all levels of public and private decision-making.

The report is the result of a three year collaboration between public and private interests that included scientists, government representatives, business, and the general public. Over 70 workshops and listening sessions were held to provide additional input to the process. Material that was used to develop the assessment includes an extensive collection of scientific peer-reviewed research, technical input reports, and other publicly accessible sources. The report was reviewed extensively by the public and experts, including federal agencies and a panel of the National Academy of Sciences.

Michigan State University (MSU) professors who were involved in developing the National Climate Assessment include Dr. Jeff Andresen (Department of Geography), Dr. Phil Robertson (Director of the Long-Term Ecological Research Program at Kellogg Biological Station), Dr. Julie Winkler (Department of Geography), and Dr. Tom Dietz (Department of Sociology). The Great Lakes Integrated Sciences and Assessment, a partnership between MSU, the University of Michigan, and the National Oceanic and Atmospheric Administration (NOAA), contributed to the Midwest report.

The Assessment highlights several important key messages:

  • Human health. Climate change threatens human health and well-being in many ways. This includes impacts from increased extreme weather events, wildfire, decreased air quality, threats to mental health, and illnesses transmitted by food, water, and disease-carrying insects.
  • Forests. Climate change is increasing the vulnerability of many forests ecosystem changes and tree mortality through fire, infestations, drought, and disease outbreaks.
  • Water resources. Water quality and water supply reliability are jeopardized by climate change in a variety of ways that affect ecosystems and livelihoods. Two examples of how this is currently happening are increased duration and intensity of droughts and more extreme precipitation events causing water runoff. For more information on this message, read these Michigan State University Extension articles, “Climate change and water resources— a national assessment” and “How is the water cycle affected by climate change.”
  • Agriculture. Climate disruptions to agriculture have been increasing and are projected to become more severe over this century.
  • Indigenous peoples, lands, and resources. Climate change poses particular threats to Indigenous Peoples’ health, well-being, and ways of life. One example involves access to traditional foods that have provided sustenance, and cultural, economic, medicinal and community health benefits for generations of Native Peoples.
  • Ecosystems and biodiversity. Ecosystems and the benefits they provide to society are being affected by climate change. The capacity of ecosystems to buffer the impacts of extreme events is being overwhelmed.
  • Energy, water, and land use. Energy, water, and land systems interact in many ways. The combination of these factors affects climate change vulnerability as well as adaptation and mitigation options for different regions of the country. For additional details on this message, read the MSU Extension article, “Energy, water, and land use: how do they affect each other in a changing climate?”
  • Urban systems, infrastructure, and vulnerability. Climate change and its impacts threaten the well-being of urban residents across the U.S. Essential infrastructure systems such as water, energy supply, and transportation, will increasingly be compromised by interrelated climate change impacts. The nation’s economy, security, and culture all depend on the resilience of these urban systems. For additional details on this message, read the MSU Extension article, “Local government and climate change: assess your community’s flood resilience.”
  • Land use and land cover change. Choices about land-use and land cover patterns have affected how vulnerable or resilient human communities and ecosystems are to the effects of climate change. This message discusses how choices about land use may provide a means of reducing greenhouse gas emissions. For additional details, read the MSU Extension article, “Local government and climate change: planning for rainfall intensification in the Midwest.”
  • Transportation. Impacts of climate change, for example, extreme weather events, are affecting the reliability and capacity of the U.S. transportation system, and are causing disruption in transportation networks across the country. These impacts can be reduced through rerouting, mode change, and a wide range of adaptive actions.
  • Energy supply and use. Higher summer temperatures will increase electricity use, causing higher summer peak loads, while warmer winters will decrease energy demands for heating. Net electricity use is projected to increase. As new investments in energy technologies occur, future energy systems will differ from today’s in uncertain ways. Depending on the character of changes in the energy mix, climate change will introduce new risk as well as opportunities.
  • Biogeochemical cycles. Altered biogeochemical cycles (involving a series of changes of chemical elements among different parts of the earth, for example from living to non-living, from soil to plants, etc.) coupled with climate change increase the vulnerability of biodiversity, food security, human health, and water quality to changing climate. However, natural and managed shifts in major biogeochemical cycles can help limit rates of climate change.
  • Oceans. Ocean waters are becoming warmer and more acidic, broadly affecting ocean circulation, chemistry, ecosystems, and marine life.
  • Adaption and Mitigation. Planning for adaptation (to address and prepare for impacts) and mitigation (to reduce future climate change) is becoming more widespread, but current implementation efforts are insufficient to avoid increasingly negative social, environmental, and economic consequences.
  • Decision support. Decisions about how to address climate change can be complex, and responses will require a combination of adaptation and mitigation actions. Decision-makers need help integrating scientific information into adaptation and mitigation decisions.

Full access to the 2014 National Climate Assessment is available at the U.S. Global Change Research Program’s website. The full report of the National Climate Assessment provides an in-depth look at climate change impacts on the U.S and details the multitude of ways climate change is already affecting and will increasingly affect the lives of Americans.

There is also a highlights version of the Assessment available which provides the major findings and selected highlights from the full report. It is organized around the National Climate Assessment’s 12 report findings. A National Climate Assessment Overview document is available which serves as a brief summary of the full report version of the Assessment. It discusses the most important impacts at the national level rather than trying to provide a comprehensive summary of the entire assessment. A Frequently Asked Questions (FAQ) document and a Climate Science Assessment are also available on climate change impacts in the U.S.

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