THE SCIENCE IS IN
Increasing concentrations of greenhouse gases like carbon dioxide, methane, and nitrous oxide, produced in mass quantities by society’s combustion of fossil fuels for energy, now cloak the earth. These increasing greenhouse gas concentrations are causing the atmosphere to retain a greater proportion of the sun’s energy, warming the climate much like the interior of a greenhouse. The world’s preeminent scientists have firmly established that human production of greenhouse gases is responsible for the unprecedented rate of warming over the past century and will lead to much greater changes in this century and beyond.
As a result, extraordinary human-induced changes to our planet are currently underway, and things are literally heating up. The entire earth, and especially the Arctic, is warming more rapidly than scientists projected even just a few years ago. Average winter temperatures have already risen by over 7º F in some parts of Alaska, and will likely rise by 18 º F over the Arctic oceans in the next century. Arctic sea ice is disappearing at an alarming rate, and hit a new record minimum in September 2005.
 ACIA. 2004. Impacts of a Warming Climate: Arctic Climate Impact Assessment. Cambridge University Press. Available at http://amap.no/acia/.
Large glaciers in Greenland are melting at three times the rate of just several years ago, and water collecting at the base of the glaciers is encouraging further disintegration. Complete melting of the Greenland ice sheet would raise sea level by over 21 feet. More temperate regions are also feeling the impacts that have long been predicted: more frequent and extreme heat waves and droughts, and more intense hurricanes in the Caribbean and Atlantic regions.
GLOBAL WARMING AND EXTINCTION
Climate change poses an overwhelming threat to biodiversity. In a landmark study published in Nature, researchers found that 18 to 35 percent of species studied in a survey of 20 percent of the Earth’s land area will be committed to extinction by the year 2050 if greenhouse gas emission trends continue. Climate change will alter species’ habitats, and therefore the distribution and abundance of many plants and animals. Species that cannot adapt to new conditions or migrate to more suitable areas will become extinct. Lower levels of greenhouse gas emissions will result in less warming and change, and, therefore, fewer extinctions.
The Big Chill ©Thomas D. Mangelsen/Imagesofnaturestock.com. Polar bears are threatened with extinction because their sea ice habitat is melting away due to global warming.
Please click the links on the left for more on individual species already at high risk, including the polar bear, numerous penguin species, and Caribbean corals, all of which the Center is working to protect.
THE HUMAN COST
Global warming exacts an enormous human and economic toll as well. Climate change is already responsible for over 150,000 human deaths per year, according to the World Health Organization. And the Stern Review on the Economics of Climate Change predicts that unabated emissions will cost the world between five and 20 percent of gross domestic product annually, or between $1.5 and $6 trillion. However, the full ramifications of global warming are almost impossible to calculate at this time. What we do know already is that they are very likely to be catastrophic.
TEN YEARS TO ACT
Recent studies in the world’s leading scientific journals indicate that due to the lag time between emissions and the earth’s climatic adjustment to them, we have already committed the planet to a certain warming trajectory we cannot halt. In other words, even if all anthropogenic emissions ceased tomorrow, we would still be committed to about a doubling of the warming we have already experienced. But this does not mean we should not act quickly and decisively — in fact it reinforces the urgent need to do so.
Leading scientists have issued urgent warnings that future warming must be limited to no more than 1° C (1.8° F) above year 2000 levels, in order to avoid triggering climate feedbacks leading to even greater warming, and therefore catastrophic impacts such as 20 feet of sea level rise and extinction of a third of the world’s species.
Further, scientists advise that atmospheric carbon dioxide levels must be kept below about 450 parts per million to limit future warming to less than 1° C. With atmospheric carbon dioxide levels already at over 380 parts per million and increasing by more than two parts per million per year, just ten more years of “business as usual” emissions trajectories would make it difficult or impossible to avoid the disaster scenario.
We have, at most, ten years to act.
THE CENTER’S WORK ON GLOBAL WARMING
The Center’s Climate, Air, and Energy Program works to reduce U.S. greenhouse gas emissions to protect biological diversity, our environment, and public health. Our multifaceted approach involves national and state policy advocacy for mandatory emissions caps; petitions and litigation to protect species and habitats at urgent risk of harm from global warming and to promote government compliance with energy laws; and advocacy for new federal legislation to improve management and protection of highest-risk species. We work to educate the public about the impacts of climate change on our world and the animals and plants that live in it and to build the political will to enact solutions.
The good news is that solutions are readily available to avoid the worst impacts of global warming. Measures like increasing energy efficiency, fuel economy, and changing land use and transportation patterns with existing technology could slash current emissions while improving our quality of life and benefiting the economy. And the regulation of greenhouse gas pollution will spur the development and deployment of new technologies far beyond what is possible today.
At the same time, the measures necessary to protect the species most at risk from global warming will help improve the way we manage our public lands and ecosystems.
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