What is science telling us? Mounting climate science evidence shows that our atmosphere is dangerously out of balance and the climate we depend on for our food, water and health is changing rapidly. Studies published since the Intergovernmental Panel on Climate Change issued its comprehensive report in 2007 point ever more compellingly to the urgent need for swift, deep reductions of heat-trapping gasses to avoid catastrophic climate change. United States leadership is essential, and there is no time to waste.

Click here for updated CO2 data from the Mauna Loa Observatory.

Climate Change is already having real impacts:

  • Sea levels are projected to rise faster than we thought the last time the IPCC weighed in. Without emissions reductions, a 2.6 foot rise is likely by the end of the century and a 6.6 foot rise is possible.

Science indicates an even stronger need to act than previously thought:

  • Globally, an estimated 8.7 billion tons of carbon were emitted in 2008 from burning coal, oil and natural gas, more than a 40 percent increase from 1990.
  • The ocean’s ability to absorb carbon dioxide is declining as it heats up and becomes more acidic. In 1959, the ocean absorbed 60 percent of the extra CO2 we put in the atmosphere. In 2008, it only absorbed 55 percent.
  • Studies indicate that the Earth will take a long time — at least a thousand years — to come back into balance and recover from the excess CO2 we are putting into the atmosphere.

Every day of delay locks in more warming for ourselves and future generations.

Responding to skeptics: Given the preponderance of scientific evidence, it is hard to believe that there are still climate change deniers out there, but there are. For an excellent, well-researched article responding to some of the skeptics common charges and misperceptions see “Seven Answers to Climate Contrarian Nonsense” by the former Chief Editor of Scientific American. This is a great piece to use the next time you visit your skeptical relative in Ohio, Wyoming or Alabama.

Thanks to Union of Concerned Scientists for much of the information on this page.

A Few More Science Facts

  • Naomi Oreskes, a science historian at UC San Diego reviewed 928 abstracts of peer-reviewed articles on climate change published in scientific journals between 1993 and 2003 and could not find a single one that challenged the scientific consensus that global warming is happening and that it is primarily human caused.
  • The Intergovernmental Panel on Climate Change which involved over 2000 scientists representing 100 countries, the largest peer-reviewed scientific collaboration in history, has concluded that human contributions to climate change is substantial and that we need to move quickly to reduce our consumption of fossil fuels, the largest contributor to global warming;


  • Further, the National Academy of Sciences, the American Geophysical Union, American Meteorological Society and the American Association for the Advancement of Science all agree that the scientific evidence is that global warming is happening and human activity is the predominant contributor.


  • The National Oceanic and Atmospheric Association determined that 19 of the hottest 20 years on record have occurred since 1980. 2010 was the hottest year since the instrumental temperature record began. The temperature record is bolstered by a host of evidence from all over the globe, including the receding of glaciers worldwide, the melting of the Greenland Ice Cap, huge losses of sea ice (250 million acres since 1979) an impact on bird and butterfly migratory patterns and habitat, a change in the timing of the seasons, the thawing of permafrost melting (including the reabsorption by the tundra of 120 lakes in Siberia) and much more.