Over the years of his presidency, George Bush's attitude toward climate change has evolved.
As a candidate, he pledged to control carbon dioxide (CO2) emissions – the main greenhouse gas linked to rising global temperatures. Once elected, he reversed that position as Vice President Dick Cheney took the lead on crafting the administration's energy policy.
Mr. Bush rejected the Kyoto Protocol, the international agreement to reduce greenhouse gases, on the grounds that it would harm the US economy and also because major polluters (especially China) were exempt from the treaty.
In recent years, he has more regularly and readily acknowledged the reality of climate change and the need to do something about it. More evidence in this direction came recently when White House science adviser John Marburger acknowledged that the planet may become "unlivable" without cuts in CO2. He told the BBC:
"I think there is widespread agreement on certain basics, and one of the most important is that we are producing far more CO2 from fossil fuels than we ought to be. And it's going to lead to trouble unless we can begin to reduce the amount of fossil fuels we are burning and using in our economies.... The CO2 accumulates in the atmosphere, and there's no end point, it just gets hotter and hotter, and so at some point it becomes unlivable."
In essence, Dr. Marburger, a physicist and former director of Brookhaven National Laboratory, is endorsing the latest major review of climate science from the United Nations Intergovernmental Panel on Climate Change. The IPCC now says that "most of the observed increase in global average temperatures since the mid-20th century is very likely [defined as with more than 90 percent certainty] due to the observed increase in anthropogenic [human-induced] greenhouse-gas concentrations."
By agreeing with this conclusion, reports the British newspaper The Telegraph:
" [Marburger has] delivered the strongest statement yet from within the US administration that greenhouse-gas emissions caused by human activity are to blame for climate change."
Marburger's comments set the scene for two major gatherings next week on climate issues. On Sept. 24, the UN General Assembly has scheduled a day-long seminar on future international agreements, focusing on four themes: mitigation, adaptation, technology, and financing. More than 70 heads of state (including Bush) are expected to attend, making it the largest meeting ever of world leaders on climate change.
Later in the week, the US president hosts a two-day meeting of the 20 nations most responsible for emitting greenhouse gases. As Bush wrote in his invitation to heads of state:
"The United States is committed to collaborating with other major economies to agree on a detailed contribution for a new global framework by the end of 2008, which would contribute to a global agreement under the U.N. Framework Convention on Climate Change by 2009.... We expect to place special emphasis on how major economies can, in close cooperation with the private sector, accelerate the development and deployment of clean technologies."
Critics have said that by calling for meetings late in his tenure as president, Bush is merely running out the clock before he turns over the problem to his successor. But in his invitation to world leaders, the president indicated that his view may have changed as the IPCC and other organizations confirmed with greater certainty the reality and causes of climate change. He wrote:
"In recent years, science has deepened our understanding of climate change and opened new possibilities for confronting it."
That understanding apparently includes more certainty that greenhouse gases are a major cause. Last week, ScientificAmerican.com reported new evidence found in fossilized shells that confirms the link between carbon dioxide levels in the atmosphere and warmer oceans.
Ancient species of squids and clams stored rare isotopes of carbon and oxygen in their calcium carbonate shells that then fossilized. Says the ScientificAmerican.com story:
"By examining the percentage of such bonded rare isotopes, scientists have now confirmed the link between carbon dioxide levels and warmer ancient climates.... The finding adds yet more weight to the contention that greenhouse gases drive climate change, and bode ill for the present increases in atmospheric concentrations of such gases."