BioEd Online

Throughout his time in office, President George Bush has been slammed by environmentalists for avoiding steps to reduce global warming. Climate experts recommend cuts in greenhouse-gas emissions - and John Kerry pledges to take a greener stance.

While acknowledging that humans are at least partly responsible for the Earth's gradual warming, the current administration has stressed uncertainties in the scientific data. It says that it is unclear how much natural climate fluctuations contribute to observed temperature changes, and how much the climate will change in the future. "We do not know how fast change will occur, or even how some of our actions could impact it," Bush said in a White House speech in June 2001.

Because of these uncertainties, the Bush administration has opposed the introduction of enforced cuts in greenhouse-gas emissions and has refused to sign up to the Kyoto Protocol. Instead, Bush's domestic policies favour voluntary reductions by industry and moves to cleaner fuels and fuel-burning technologies.

By contrast, Kerry has promised to resume international climate-change negotiations and to match the efforts of other industrial countries to cut emissions. But he has not released any specific numbers or targets during the campaign. Furthermore, a Kerry-Edwards administration will not sign up to the Kyoto Protocol, partly because the short-term goals are unfeasible, says Devona Dolliole, a spokeswoman for the campaign. She says that they want to develop an alternative to Kyoto with more achievable targets.

For their part, climate scientists are chafing against Bush's approach to climate-change research. They are satisfied by evidence that man's emissions are contributing to global warming, and that cuts in emissions would help to improve the situation. "You can't find very many climate scientists who are happy with the administration," says Stephen Schneider, a climatologist from Stanford University, California.

Michael MacCracken, an expert in the field at the Climate Institute in Washington DC, says that renewed international negotiations are important to the climate community. One of the best ways to lower emissions, he says, is to introduce a system in which greenhouse-gas emitters pay for their pollution. MacCraken, having seen Kerry argue in Senate hearings on climate change, believes that the presidential challenger shares his views.