Dear Governor Brown and California state legislators,

California's continued leadership is needed now more than ever to address the risks of a dangerously warming climate.

The science is clear that human activity is the dominant cause of global warming over the last half-century. If heat-trapping emissions continue to rise, the scope and severity of impacts will accelerate. Communities across California are already being forced to cope with increased wildfires, more frequent and extreme heat waves, a strained water management system, growing risks to agricultural crops, greater summer electricity demand, and more coastal flooding.

While we must adapt to those impacts of climate change that cannot be avoided, California must also continue to take ambitious steps to reduce its heat-trapping emissions. California deserves tremendous credit for putting innovative climate policies into practice, spurring investment, innovation, and jobs in a growing "green technology" sector. The state is well positioned to maintain its leadership in this effort.

We urge you to take decisive action this year to ensure that California:

• reduces heat-trapping emissions to 80 percent below 1990 levels by 2050;

• increases its share of electricity generated from renewable sources to 50 percent by 2030; and

• reduces petroleum use in the transportation sector 50 percent by 2030.

  These objectives are currently reflected in two bills before the California state legislature: Senate Bills 32 and 350. As scientists and researchers with expertise in climate change, its impacts, and its solutions, we ask you to support policies that will ensure California meets these goals.

This letter was open to scientists, researchers, and economists with a Ph.D. whose peer-reviewed research focuses on the causes of climate change, the impacts of climate change, or solutions to climate change.

Steven Allison, Ph.D., University of California, Irvine

Simone Aloisio, Ph.D., California State University, Channel Islands

Cort Anastasio, Ph.D., University of California, Davis

Ray Anderson, Ph.D., USDA, Agricultural Research Service

Kenneth Arrow, Ph.D., Stanford University

Gregory Asner, Ph.D., Carnegie Institution for Science

Jeffrey Bada, Ph.D., Scripps Institution of Oceanography

Dennis Baldocchi, Ph.D., University of California, Berkeley

Roger Bales, Ph.D., University of California, Merced

Asmeret Asefaw Berhe, Ph.D., University of California, Merced

Hilda Blanco, Ph.D., University of Southern California

Robert Brecha, Ph.D., University of Dayton

Holger Brix, Ph.D., University of California, Los Angeles

Chris Busch, Ph.D., Energy Innovation

Becky Chaplin, Ph.D., Stanford University

Karen Chapple, Ph.D., University of California, Berkeley

Juliet Christian-Smith, Ph.D., Union of Concerned Scientists

David Cleveland, Ph.D., University of California, Santa Barbara

Erin Conlisk, Ph.D., University of California, Berkeley

Eugene Cordero, Ph.D., San Jose State University

Helen Cox, Ph.D., California State University, Northridge

Gretchen Daily, Ph.D., Stanford University

Bruce Daniels, Ph.D., Hydroclimatology.com

Jeannie Darby, Ph.D., University of California, Davis

John Dracup, Ph.D., University of California, Berkeley

Ellen Druffel, Ph.D., University of California, Irvine

Tim Duane, Ph.D., University of California, Santa Cruz

Robert Dunbar, Ph.D., Stanford University

Y. Hossein Farzin, Ph.D., University of California, Davis

Howard Feder, Ph.D., University of Alaska, Fairbanks (Retired)

Gabriel Filippelli, Ph.D., Indiana University - Purdue University Indianapolis

Anthony Fisher, Ph.D., University of California, Berkeley

Graham Fogg, Ph.D., University of California, Davis

Lee Friedman, Ph.D., University of California, Berkeley

Peter Frumhoff, Ph.D., Union of Concerned Scientists

Jed Fuhrman, Ph.D., University of Southern California

Robert Gamache, Ph.D., University of Massachusetts, Lowell

Gregg Garfin, Ph.D., University of Arizona

Catherine Gautier, Ph.D., University of California, Santa Barbara

Alexander Gershenson, Ph.D. San Jose State University

Teamrat Ghezzehei, Ph.D., University of California, Merced

J. Keith Gilless, Ph.D., University of California, Berkeley

Steven Glaser, Ph.D., University of California, Berkeley

Peter Gleick, Ph.D., Pacific Institute

Wilson Goddard, Ph.D., Goddard & Goddard Engineering

Gary Griggs, Ph.D., University of California, Santa Cruz

Andrew Gutierrez, Ph.D., University of California, Berkeley

Steven Hackett, Ph.D., Humboldt State University

Brent Haddad, Ph.D., University of California, Santa Cruz

Darwin Hall, Ph.D., California State University, Fullerton

W. Michael Hanemann, Ph.D., University of California, Berkeley

Thomas Harmon, Ph.D., University of California, Merced

David Hastings, Ph.D., Eckerd College

Lelia Hawkins, Ph.D., Harvey Mudd College

Geoffrey Heal, Ph.D., Columbia University

Karen Holl, Ph.D., University of California, Santa Cruz

John Holtzclaw, Ph.D., Sierra Club

Edward Huang, Ph.D., California Institute of Environmental Design and Management

Janice Hudgings, Ph.D., Pomona College

Louise Jackson, Ph.D., University of California, Davis

Arne Jacobson, Ph.D., Humboldt State University

Mark Jacobson, Ph.D., Stanford University

Daniel Kammen, Ph.D., University of California, Berkeley

Carrie Kappel, Ph.D., University of California, Santa Barbara

Anne Kapuscinski, Ph.D., Dartmouth College

David Karowe, Ph.D., Western Michigan University

Michael Kiparsky, Ph.D., University of California, Berkeley

Jeffrey Koseff, Ph.D., Stanford University

Lara Kueppers, Ph.D., University of California, Merced

Steve LaDochy, Ph.D., California State University, Los Angeles

John Lemons, Ph.D., University of New England

Dennis Lettenmaier, Ph.D., University of California, Los Angeles

Sherman Lewis, Ph.D., California State University, East Bay

Michael Loik, Ph.D., University of California, Santa Cruz

Michael C. MacCracken, Ph.D., Climate Institute

Edward Maibach, Ph.D., George Mason University

Wade Martin, Ph.D., California State University, Long Beach

Mark Mascal, Ph.D., University of California, Davis

Edwin Maurer, Ph.D., Santa Clara University

James McCarthy, Ph.D., Harvard University

Josue Medellin-Azuara, Ph.D., University of California, Davis

Adam Millard-Ball, Ph.D. University of California, Santa Cruz

Norman Miller, Ph.D., University of California, Berkeley

Mario Molina, Ph.D., University of California, San Diego

William Moomaw, Ph.D., Tufts University

Jean Moran, Ph.D., California State University, East Bay

Emily Moran, Ph.D., University of California, Merced

Max Moritz, Ph.D., University of Califonia, Berkeley

Susanne Moser, Ph.D., Susanne Moser Research & Consulting

Dustin Mulvaney, Ph.D., San Jose State University

Knute Nadelhoffer, Ph.D., University of Michigan

Raymond Najjar, Ph.D., The Pennsylvania State University

Roz Naylor, Ph.D., Stanford University

William Nazaroff, Ph.D., University of California, Berkeley

Jimmy Nelson, Ph.D., Union of Concerned Scientists

Wallace Nichols, Ph.D., California Academy of Sciences

Deb Niemeier, Ph.D., University of California, Davis

Richard Norgaard, Ph.D., University of California, Berkeley

Richard Norris, Ph.D., Scripps Institution of Oceanography

Susan Nossal, Ph.D. University of Wisconsin, Madison

Anthony O'Geen, Ph.D., University of California, Davis

Michael O'Hare, Ph.D., University of California, Berkeley

Stephanie Ohshita, Ph.D., University of San Francisco

Patricia Oikawa, Ph.D., University of California, Berkeley

Stuart Oskamp, Ph.D., Claremont Graduate University

Jonathan Overpeck, Ph.D., University of Arizona

Doug Parker, Ph.D. University of California

Edward Parson, Ph.D., University of California, Los Angeles

Manuel Pastor, Ph.D., University of Southern California

John Pearse, Ph.D., University of California, Santa Cruz

Stacy Philpott, Ph.D., University of California, Santa Cruz

Richard Plevin, Ph.D. University of California, Davis

James Powell, Ph.D., University of Southern California

Michael Prather, Ph.D., University of California, Irvine

Daniel Press, Ph.D., University of California, Santa Cruz

Veerabhadran Ramanathan, Ph.D., Scripps Institution of Oceanography

Greg Rau, Ph.D., University of California, Santa Cruz

David Reichmuth, Ph.D., Union of Concerned Scientists

Robert Rhew, Ph.D., University of California, Berkeley

Eric Rignot, Ph.D., University of California, Irvine

Alan Robock, Ph.D., Rutgers University

David Roland-Holst, Ph.D., University of California, Berkeley

Peter Saeta, Ph.D., Harvey Mudd College

Jayant Sathaye, Ph.D., Lawerence Berkeley National Laboratory

Whendee Silver, Ph.D., University of California, Berkeley

John Skillman, Ph.D., California State University, San Bernardino

Leonard Sklar, Ph.D., San Francisco State University

Kenneth Small, Ph.D., University of California, Irvine

Raymond Smith, Ph.D., University of California, Santa Barbara

Kirk R Smith, Ph.D., University of California, Berkeley

George Somero, Ph.D., Stanford University

Richard C.J. Somerville, Ph.D., Scripps Institution of Oceanography

Wayne Spencer, Ph.D., Conservation Biology Institute

Michael Springborn, Ph.D., University of California, Davis

Scott Stephens, Ph.D., University of California, Berkeley

Iris Stewart-Frey, Ph.D., Santa Clara University

William Sundstrom, Ph.D., Santa Clara University

Andrew Szasz, Ph.D., University of California, Santa Cruz

Eugene Takle, Ph.D., Iowa State University

Dee Trent, Ph.D., Citrus Community College

Aradhna Tripati, Ph.D., University of California, Los Angeles

Slawek Tulaczyk, Ph.D., University of California, Santa Cruz

Susan Ustin, Ph.D., University of California, Davis

Hartwell Welsh, Ph.D., USDA Forest Service

A. Leroy Westerling, Ph.D., University of California, Merced

Robert Wolf, Ph.D., Harvey Mudd College

Carl Wunsch, Ph.D., Harvard University

Erika Zavaleta, Ph.D., University of California, Santa Cruz

Louis Zeidberg, Ph.D., California State University, Monterey Bay

Charlie Zender, Ph.D., University of California, Irvine