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Consensus: 97% of climate scientists agree

Temperature data from four international science institutions. All show rapid warming in the past few decades and that the last decade has been the warmest on record.

Temperature data from four international science institutions. All show rapid warming in the past few decades and that the last decade has been the warmest on record.

Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities,1and most of the leading scientific organizations worldwide have issued public statements endorsing this position. The following is a partial list of these organizations, along with links to their published statements and a selection of related resources.


  • Statement on climate change from 18 scientific associations

    "Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver." (2009)2

  • AAAS emblem

    American Association for the Advancement of Science

    "The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society." (2006)3

  • ACS emblem

    American Chemical Society

    "Comprehensive scientific assessments of our current and potential future climates clearly indicate that climate change is real, largely attributable to emissions from human activities, and potentially a very serious problem." (2004)4

  • AGU emblem

    American Geophysical Union

    "Human‐induced climate change requires urgent action. Humanity is the major influence on the global climate change observed over the past 50 years. Rapid societal responses can significantly lessen negative outcomes." (Adopted 2003, revised and reaffirmed 2007, 2012, 2013)5

  • AMA emblem

    American Medical Association

    "Our AMA ... supports the findings of the Intergovernmental Panel on Climate Change’s fourth assessment report and concurs with the scientific consensus that the Earth is undergoing adverse global climate change and that anthropogenic contributions are significant." (2013)6

  • AMS emblem

    American Meteorological Society

    "It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide." (2012)7

  • APS emblem

    American Physical Society

    "The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now." (2007)8

  • GSA emblem

    The Geological Society of America

    "The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s." (2006; revised 2010)9


  • International academies: Joint statement

    "Climate change is real. There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001)." (2005, 11 international science academies)10

  • USNAS emblem

    U.S. National Academy of Sciences

    "The scientific understanding of climate change is now sufficiently clear to justify taking steps to reduce the amount of greenhouse gases in the atmosphere." (2005)11


  • USGCRP emblem

    U.S. Global Change Research Program

    "The global warming of the past 50 years is due primarily to human-induced increases in heat-trapping gases. Human 'fingerprints' also have been identified in many other aspects of the climate system, including changes in ocean heat content, precipitation, atmospheric moisture, and Arctic sea ice." (2009, 13 U.S. government departments and agencies)12


  • IPCC emblem

    Intergovernmental Panel on Climate Change

    “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.”13

    “Most of the observed increase in global average temperatures since the mid-20th century is very likely* due to the observed increase in anthropogenic greenhouse gas concentrations.”14

     *IPCC defines ‘very likely’ as greater than 90 percent probability of occurrence.