Obama sorting Bush's environment legacy
But even those who view his environmental record most harshly acknowledge that he also took significant action. He improved air quality, gave renewable energy a large financial boost, left behind the largest marine sanctuaries ever established and started a dialogue that could help lead to the next international treaty on climate change.
Bush and his aides stressed that he tried to find a balance between the environment and the economy.
Obama has called that a false choice. He intends, he says, to promote economic growth and develop new sources of energy while at the same time protecting the natural world.
So far, he has devoted most attention to reversing direction on various issues. Within days of taking the oath of office, he froze a series of last-minute actions by the departing Bush team and ordered regulators to write tough new rules on automobile emissions and fuel economy.
Earlier this week, he upended Bush administration policies on drilling in Utah and the operation of coal-fired power plants.
But as Obama moves further, a bigger challenge may be to decide how much to preserve of the broad landscape left to him by Bush - environmental and energy policies that encompass land, air, water, wildlife and climate.
The public view of Bush's record on global warming was largely set by his blunt rejection of the Kyoto Protocol, his swift abandonment of his campaign pledge to restrict some greenhouse gases and the disclosures of interference by presidential appointees with government climate scientists.
Overall, Claussen said, Bush's climate legacy was mainly one of delay and lost opportunities. Through most of his presidency, Bush largely framed his approach to global warming around two talking points - the uncertainties in forecasts of a dangerously human-heated world and the certainty that economic harm would come from mandatory cuts in greenhouse gas emissions.
Obama has taken precisely the opposite tack. He spoke late last month of the specter of "violent conflict, terrible storms, shrinking coastlines" and other perils from unchecked warming, while pressing his vision of prosperity rebuilt around clean cars and pollution-free power from the wind and sun.
Many analysts say that Obama must navigate among an array of campaigners, lobbyists and lawmakers with particular interests - from dependency on coal to aversion to power lines or nuclear plants. But if he makes too many political compromises, he may find his plan fails on environmental grounds.