Fourth National Climate Assessment

Fourth National Climate Assessment (NCA4) 2017/2018 is a 1,500 page two-part congressionally mandated report by the U.S. Global Change Research Program (USGCRP)[1]—the first of its kind by the Trump administration, who released the report on November 23, 2018.[2] The climate assessment process, with a report to be submitted to Congress every four years, is mandated by law through the Global Change Research Act of 1990. The report, which took two years to complete, is the fourth in a series of National Climate Assessments (NCA) which included NCA1 (2000), NCA2 (2009), and NCA3 (2014).[3]

Volume 1 of NCA4, "Climate Science Special Report" (CSSR) was released in October 2017.[4][5][6] In the CSSR, researchers reported that "it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence."[4][6]: 22 

Volume 2, entitled "Impacts, Risks, and Adaptation in the United States", was released on November 23, 2018.[7] According to NOAA, "human health and safety" and American "quality of life" is "increasingly vulnerable to the impacts of climate change".[8] Like the previous reports in this series, the NCA4 is a "stand-alone report of the state of science relating to climate change and its physical impacts".

The authors say that without more significant mitigation efforts, there will be "substantial damages on the U.S. economy, human health, and the environment. Under scenarios with high emissions and limited or no adaptation, annual losses in some sectors are estimated to grow to hundreds of billions of dollars by the end of the century."[9]

While the CSSR is "designed to be an authoritative assessment of the science of climate change" in the United States, it does not include policy recommendations.[10]

Fifth National Climate Assessment (NCA5) was published in November 2023.[11]

  1. ^ Cite error: The named reference UCS_Ekwurzel_2018 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference WaPo_20181123 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference latimes_Barboza_20181123 was invoked but never defined (see the help page).
  4. ^ a b Wehner, M. F.; Arnold, J. R.; Knutson, T.; Kunkel, K. E.; LeGrande, A. N. (2017). Wuebbles, D. J.; Fahey, D. W.; Hibbard, K. A.; Dokken, D. J.; Stewart, B. C.; Maycock, T. K. (eds.). Droughts, Floods, and Wildfires (Report). Climate Science Special Report: Fourth National Climate Assessment. Vol. 1. Washington, DC: U.S. Global Change Research Program. pp. 231–256. doi:10.7930/J0CJ8BNN.
  5. ^ Cite error: The named reference NCA4_Vol1_Wuebbles_2017_full was invoked but never defined (see the help page).
  6. ^ a b Leggett, Jane A. (February 1, 2018). Evolving Assessments of Human and Natural Contributions to Climate Change (PDF) (Report). Congressional Research Service (CRS). p. 22. Retrieved November 23, 2018. This CRS report provides context for the Administration's Climate Science Special Report (October 2017) by tracing the evolution of scientific understanding and confidence regarding the drivers of recent global climate change.
  7. ^ Impacts, Risks, and Adaptation in the United States (Report). National Climate Assessment. Vol. 2. November 23, 2018. Retrieved November 23, 2018.
  8. ^ "New federal climate assessment for U.S. released: Report highlights impacts, risks and adaptations to climate change". National Oceanic and Atmospheric Administration (NOAA). November 23, 2018. Retrieved November 23, 2018.
  9. ^ Cite error: The named reference NCA4_vol2_Chap29 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference NCA4_Vol1_Wuebbles_2017_about was invoked but never defined (see the help page).
  11. ^ "Fifth National Climate Assessment". U.S. Global Change Research Program. November 2023. Retrieved 2023-11-25.