Full text of an open letter from 255 members of the US National Academy of Sciences in defence of climate research

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.

Scientific conclusions derive from an understanding of basic laws supported by laboratory experiments, observations of nature, and mathematical and computer modelling. Like all human beings, scientists make mistakes, but the scientific process is designed to find and correct them. This process is inherently adversarial— scientists build reputations and gain recognition not only for supporting conventional wisdom, but even more so for demonstrating that the scientific consensus is wrong and that there is a better explanation. That's what Galileo, Pasteur, Darwin, and Einstein did. But when some conclusions have been thoroughly and deeply tested, questioned, and examined, they gain the status of "well-established theories" and are often spoken of as "facts."

For instance, there is compelling scientific evidence that our planet is about 4.5bn years old (the theory of the origin of Earth), that our universe was born from a single event about 14bn years ago (the Big Bang theory), and that today's organisms evolved from ones living in the past (the theory of evolution). Even as these are overwhelmingly accepted by the scientific community, fame still awaits anyone who could show these theories to be wrong. Climate change now falls into this category: there is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend.

Many recent assaults on climate science and, more disturbingly, on climate scientists by climate change deniers, are typically driven by special interests or dogma, not by an honest effort to provide an alternative theory that credibly satisfies the evidence. The Intergovernmental Panel on Climate Change (IPCC) and other scientific assessments of climate change, which involve thousands of scientists producing massive and comprehensive reports, have, quite expectedly and normally, made some mistakes. When errors are pointed out, they are corrected.

But there is nothing remotely identified in the recent events that changes the fundamental conclusions about climate change:

(i) The planet is warming due to increased concentrations of heat-trapping gases in our atmosphere. A snowy winter in Washington does not alter this fact.

(ii) Most of the increase in the concentration of these gases over the last century is due to human activities, especially the burning of fossil fuels and deforestation.

(iii) Natural causes always play a role in changing Earth's climate, but are now being overwhelmed by human-induced changes.

(iv) Warming the planet will cause many other climatic patterns to change at speeds unprecedented in modern times, including increasing rates of sea-level rise and alterations in the hydrologic cycle. Rising concentrations of carbon dioxide are making the oceans more acidic.

(v) The combination of these complex climate changes threatens coastal communities and cities, our food and water supplies, marine and freshwater ecosystems, forests, high mountain environments, and far more.

Much more can be, and has been, said by the world's scientific societies, national academies, and individuals, but these conclusions should be enough to indicate why scientists are concerned about what future generations will face from business- as-usual practices. We urge our policymakers and the public to move forward immediately to address the causes of climate change, including the unrestrained burning of fossil fuels.

We also call for an end to McCarthy- like threats of criminal prosecution against our colleagues based on innuendo and guilt by association, the harassment of scientists by politicians seeking distractions to avoid taking action, and the outright lies being spread about them. Society has two choices: we can ignore the science and hide our heads in the sand and hope we are lucky, or we can act in the public interest to reduce the threat of global climate change quickly and substantively. The good news is that smart and effective actions are possible. But delay must not be an option.

• The signatories are all members of the US National Academy of Sciences but are not speaking on its behalf or on behalf of their institutions.

Adams, Robert McCormick, University of California, San Diego

Amasino, Richard M, University of Wisconsin

Anders, Edward, University of Chicago

Anderson, David J, California Institute of Technology

Anderson, Wyatt W, University of Georgia

Anselin, Luc E, Arizona State University

Arroyo, Mary Kalin, University of Chile

Asfaw, Berhane, Rift Valley Research Service

Ayala, Francisco J, University of California, Irvine

Bax, Adriaan, National Institutes of Health

Bebbington, Anthony J, University of Manchester

Bell, Gordon, Microsoft Research

Bennett, Michael V L, Albert Einstein College of Medicine

Bennetzen, Jeffrey L, University of Georgia

Berenbaum, May R, University of Illinois

Berlin, Overton Brent, University of Georgia

Bjorkman, Pamela J, California Institute of Technology

Blackburn, Elizabeth, University of California, San Francisco

Blamont, Jacques E, Centre National d' Etudes Spatiales

Botchan, Michael R, University of California, Berkeley

Boyer, John S, University of Delaware

Boyle, Ed A, Massachusetts Institute of Technology

Branton, Daniel, Harvard University

Briggs, Steven P, University of California, San Diego

Briggs, Winslow R, Carnegie Institution of Washington

Brill, Winston J, Winston J. Brill and Associates

Britten, Roy J, California Institute of Technology

Broecker, Wallace S, Lamont-Doherty Earth Observatory and Columbia University

Brown, James H, University of New Mexico

Brown, Patrick O, Stanford University School of Medicine

Brunger, Axel T, Stanford University

Cairns, Jr John, Virginia Polytechnic Institute and State University

Canfield, Donald E, University of Southern Denmark

Carpenter, Stephen R, University of Wisconsin

Carrington, James C, Oregon State University

Cashmore, Anthony R, University of Pennsylvania

Castilla, Juan Carlos, Pontificia Universidad Católica de Chile

Cazenave, Anny, Centre National d' Etudes Spatiales

Chapin, III F, Stuart, University of Alaska

Ciechanover, Aaron J, Technion-Israel Institute of Technology

Clapham, David E, Harvard Medical School

Clark, William C, Harvard University

Clayton, Robert N, University of Chicago

Coe, Michael D, Yale University

Conwell, Esther M, University of Rochester

Cowling, Ellis B, North Carolina State University

Cowling, Richard M, Nelson Mandela Metropolitan University

Cox, Charles S, University of California, San Diego

Croteau, Rodney B, Washington State University

Crothers, Donald M, Yale University

Crutzen, Paul J, Max Planck Institute for Chemistry

Daily, Gretchen C, Stanford University

Dalrymple, Brent G, Oregon State University

Dangl, Jeffrey L, University of North Carolina

Darst, Seth A, Rockefeller University

Davies, David R, National Institutes of Health

Davis, Margaret B, University of Minnesota, Minneapolis

De Camilli, Pietro V, Yale University School of Medicine

Dean, Caroline, John Innes Centre

DeFries, Ruth S, Columbia University

Deisenhofer, Johann, University of Texas Southwestern Medical Center at Dallas

Delmer, Deborah P, University of California, Davis

DeLong, Edward F, Massachusetts Institute of Technology

DeRosier, David J, Brandeis University

Diener, Theodor O, University of Maryland

Dirzo, Rodolfo, Stanford University

Dixon, Jack E, Howard Hughes Medical Center

Donoghue, Michael J, Yale University

Doolittle, Russell F, University of California, San Diego

Dunne, Thomas, University of California, Santa Barbara

Ehrlich, Paul R, Stanford University

Eisenstadt, Shmuel N, Hebrew University of Jerusalem

Eisner, Thomas, Cornell University

Emanuel, Kerry A, Massachusetts Institute of Technology

Englander, Walter S, University of Pennsylvania School of Medicine

Ernst, W, G, Stanford University

Falkowski, Paul G, Rutgers, State University of New Jersey

Feher, George, University of California, San Diego

Ferejohn, John A, Stanford University

Fersht, Sir Alan, University of Cambridge

Fischer, Edmond H, University of Washington

Fischer, Robert, University of California, Berkeley

Flannery, Kent V, University of Michigan

Frank, Joachim, Columbia University

Frey, Perry A, University of Wisconsin

Fridovich, Irwin, Duke University Medical Center

Frieden, Carl, Washington University School of Medicine

Futuyma, Douglas J, Stony Brook University

Gardner, Wilford R, University of California, Berkeley

Garrett, Christopher J R, University of Victoria

Gilbert, Walter, Harvard University

Gleick, Peter H, Pacific Institute, Oakland

Goldberg, Robert B, University of California, Los Angeles

Goodenough, Ward H, University of Pennsylvania

Goodman, Corey S, venBio, LLC

Goodman, Morris, Wayne State University School of Medicine

Greengard, Paul, Rockefeller University

Hake, Sarah, Agricultural Research Service

Hammel, Gene, University of California, Berkeley

Hanson, Susan, Clark University

Harrison, Stephen C, Harvard Medical School

Hart, Stanley R, Woods Hole Oceanographic Institution

Hartl, Daniel L, Harvard University

Haselkorn, Robert, University of Chicago

Hawkes, Kristen, University of Utah

Hayes, John M, Woods Hole Oceanographic Institution

Hille, Bertil, University of Washington

Hökfelt, Tomas, Karolinska Institutet

House, James S, University of Michigan

Hout, Michael, University of California, Berkeley

Hunten, Donald M, University of Arizona

Izquierdo, Ivan A, Pontifical Catholic University of Rio Grande do Sul

Jagendorf, André T, Cornell University

Janzen, Daniel H, University of Pennsylvania

Jeanloz, Raymond, University of California, Berkeley

Jencks, Christopher S, Harvard University

Jury, William A, University of California, Riverside

Kaback, H Ronald, University of California, Los Angeles

Kailath, Thomas, Stanford University

Kay, Paul, International Computer Science Institute

Kay, Steve A, University of California, San Diego

Kennedy, Donald, Stanford University

Kerr, Allen, University of Adelaide

Kessler, Ronald C, Harvard Medical School

Khush, Gurdev S, University of California, Davis

Kieffer, Susan W, University of Illinois

Kirch, Patrick V, University of California, Berkeley

Kirk, Kent C, University of Wisconsin

Kivelson, Margaret G, University of California, Los Angeles

Klinman, Judith P, University of California, Berkeley

Klug, Sir Aaron, Medical Research Council

Knopoff, Leon, University of California, Los Angeles

Kornberg, Sir Hans, Boston University

Kutzbach, John E, University of Wisconsin

Lagarias, J Clark, University of California, Davis

Lambeck, Kurt, Australian National University

Landy, Arthur, Brown University

Langmuir, Charles H, Harvard University

Larkins, Brian A, University of Arizona

Le Pichon, Xavier T, College de France

Lenski, Richard E, Michigan State University

Leopold, Estella B, University of Washington

Levin, Simon A, Princeton University

Levitt, Michael, Stanford University School of Medicine

Likens, Gene E, Cary Institute of Ecosystem Studies

Lippincott-Schwartz, Jennifer, National Institutes of Health

Lorand, Laszlo, Northwestern University

Lovejoy, Owen C, Kent State University

Lynch, Michael, Indiana University

Mabogunje, Akin L, Foundation for Development and Environmental Initiatives

Malone, Thomas F, North Carolina State University

Manabe, Syukuro, Princeton University

Marcus, Joyce, University of Michigan

Massey, Douglas S, Princeton University

McWilliams, Jim C, University of California, Los Angeles

Medina, Ernesto, Venezuelan Institute for Scientific Research

Melosh, Jay H, Purdue University

Meltzer, David J, Southern Methodist University

Michener, Charles D, University of Kansas

Miles, Edward L, University of Washington

Mooney, Harold A, Stanford University

Moore, Peter B, Yale University

Morel, Francois M M, Princeton University

Mosley-Thompson, Ellen, Ohio State University

Moss, Bernard, National Institutes of Health

Munk, Walter H, University of California, San Diego

Myers, Norman, University of Oxford

Nair, Balakrish G, National Institute of Cholera and Enteric Diseases

Nathans, Jeremy, Johns Hopkins University School of Medicine

Nester, Eugene W, University of Washington

Nicoll, Roger A, University of California, San Francisco

Novick, Richard P, New York University School of Medicine

O'Connell, James F, University of Utah

Olsen, Paul E, Lamont-Doherty Earth Observatory of Columbia University

Opdyke, Neil D, University of Florida

Oster, George F, University of California, Berkeley

Ostrom, Elinor, Indiana University

Pace, Norman R, University of Colorado

Paine, Robert T, University of Washington

Palmiter, Richard D, University of Washington School of Medicine

Pedlosky, Joseph, Woods Hole Oceanographic Institution

Petsko, Gregory A, Brandeis University

Pettengill, Gordon H, Massachusetts Institute of Technology

Philander, George S, Princeton University

Piperno, Dolores R, Smithsonian Tropical Research Institute

Pollard, Thomas D, Yale University

Price Jr. Buford P, University of California, Berkeley

Reichard, Peter A, Karolinska Institutet

Reskin, Barbara F, University of Washington

Ricklefs, Robert E, University of Missouri

Rivest, Ronald L, Massachusetts Institute of Technology

Roberts, John D, California Institute of Technology

Romney, Kimball A, University of California, Irvine

Rossmann, Michael G, Purdue University

Russell, David W, University of Texas Southwestern Medical Center of Dallas

Rutter, William J, Synergenics, LLC

Sabloff, Jeremy A, University of Pennsylvania Museum of Archeology and Anthropology

Sagdeev, Roald Z, University of Maryland

Sahlins, Marshall D, University of Chicago

Salmond, Anne, University of Auckland

Sanes, Joshua R, Harvard University

Schekman, Randy, University of California, Berkeley

Schellnhuber, John, Potsdam Institute for Climate Impact Research

Schindler, David W, University of Alberta

Schmitt, Johanna, Brown University

Schneider, Stephen H, Woods Institute for the Environment

Schramm, Vern L, Albert Einstein College of Medicine

Sederoff Ronald R, North Carolina State University

Shatz, Carla J, Stanford University

Sherman, Fred, University of Rochester Medical Center

Sidman, Richard L, Harvard Medical School

Sieh, Kerry, Nanyang Technological University

Simons, Elwyn L, Duke University Lemur Center

Singer, Burton H, Princeton University

Singer, Maxine F, Carnegie Institution of Washington

Skyrms, Brian, University of California, Irvine

Sleep, Norman H, Stanford University

Smith, Bruce D, Smithsonian Institution

Snyder, Solomon H, Johns Hopkins University School of Medicine

Sokal, Robert R, Stony Brook University

Spencer, Charles S, American Museum of Natural History

Steitz, Thomas A, Yale University

Strier, Karen B, University of Wisconsin

Südhof, Thomas C, Stanford University School of Medicine

Taylor, Susan S, University of California, San Diego

Terborgh, John, Duke University

Thomas, David Hurst, American Museum of Natural History

Thompson, Lonnie G, Ohio State University

Tjian, Robert T, Howard Hughes Medical Institute

Turner, Monica G, University of Wisconsin

Uyeda, Seiya, Tokai University

Valentine, James W, University of California, Berkeley

Valentine, Joan Selverstone, University of California, Los Angeles

Van Etten, James L, University of Nebraska

Van Holde, Kensal E, Oregon State University

Vaughan, Martha, National Institutes of Health

Verba Sidney, Harvard University

Von Hippel, Peter H, University of Oregon

Wake, David B, University of California, Berkeley

Walker, Alan, Pennsylvania State University

Walker John E, Medical Research Council

Watson, Bruce E, Rensselaer Polytechnic Institute

Watson, Patty Jo, Washington University, St. Louis

Weigel, Detlef, Max Planck Institute for Developmental Biology

Wessler, Susan R, University of Georgia

West-Eberhard, Mary Jane, Smithsonian Tropical Research Institute

White, Tim D, University of California, Berkeley

Wilson, William Julius, Harvard University

Wolfenden, Richard V, University of North Carolina

Wood, John A, Harvard-Smithsonian Center for Astrophysics

Woodwell, George M, Woods Hole Research Center

Wright, Jr Herbert E, University of Minnesota

Wu, Carl, National Institutes of Health

Wunsch, Carl, Massachusetts Institute of Technology

Zoback, Mary Lou, Risk Management Solutions, Inc