[W]e have at most ten years—not ten years to decide upon action, but ten years to alter fundamentally the trajectory of global greenhouse emissions. ...

[W]e are near a tipping point, a point of no return, beyond which the built in momentum and feedbacks will carry us to levels of climate change with staggering consequences for humanity and all of the residents of this planet. (2006)

—Dr. James Hansen, Director NASA Goddard Institute of Space Studies

We, the signers of this declaration, urge all government leaders to demonstrate a new commitment to protecting the global environment for future generations. ... We encourage scientists and citizens around the world to hold their leaders accountable for addressing the global warming threat. Leaders must take this first step to protect future generations from dire prospects that would result from failure to meet our responsibilities toward them. ...

Climate change is likely to exacerbate ... food problems by adversely affecting water supplies, soil conditions, temperature tolerances, and growing seasons. ...

Climate change will accelerate the appalling pace at which species are now being liquidated, especially in vulnerable ecosystems. (1997)

—World Scientists' Call for Action at the Kyoto Climate Summit, signed by 1,600 scientists including 110 Nobel Laureates.

What we need now is good information and careful thinking, because in the years to come this issue will dwarf all the others combined. It will become the only issue. (2005)

—Dr. Tim Flannery, biologist and director, South Australian Museum

If carbon dioxide continues to increase, the study group finds no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible. ... However, the study group points out that the ocean, the great and ponderous flywheel of the global climate system, may be expected to slow the course of observable climate change. A wait-and-see policy may mean waiting until it is too late. (1979)

—Ad Hoc Study Group on Carbon Dioxide and Climate, National Academies of Science

Of the doomsday clocks ticking toward midnight, climate change is the most fearful.

—Dr. John Polanyi, winner Nobel Prize in Chemistry, 1986

There is enough water stored in the glaciers of Greenland and the West Antarctic Ice Sheet to raise average sea level 12 meters or more. Glaciers are melting now more rapidly than anyone had anticipated or thought possible. Three meters of sea level rise puts virtually all coastal cities, and their hundreds of millions of people, at hazard. The probability of such flooding over the next century, as the climactic disruption feeds on itself and accelerates, is high enough to warrant immediate action to stabilize the composition of the atmosphere. (2006)

—Dr. George M. Woodwell, founder and senior scientist, Woods Hole Research Center

Climate change is the single most important driving force that will negatively affect the future of the human race unless we do something about it now. (2005)

—Dr. Peter Raven, director, Missouri Botanical Garden