Michael McCarthy: The 44th President – and the first serious hope for our climate

Obama's agenda: 1. Environment

Can there ever have been a weightier in-tray than that awaiting the 44th President of the United States? When Barack Obama assumes office in five days' time, three giant problems will dominate his agenda, each one capable of daunting the most accomplished of national leaders: rescuing the US economy, dealing with the aftermath of George Bush's "war on terror", and confronting global climate change.

While the first two are of the utmost concern to US citizens fearing for their jobs and fearing a repeat of 9/11, and to Islamic nations who see themselves in the firing line, the key characteristics of the third are that is of concern to everyone in the world, and even more dangerous, in the long term, than the other two.

Yet global warming was the issue the Bush government ruthlessly sidelined, withdrawing from the Kyoto Treaty only weeks after the Texan oilman president moved into the White House and making strenuous efforts to deny the mounting scientific evidence. There can be no greater illustration of the chasm in priorities between the outgoing and incoming administrations than that the new US leader, with no ties whatsoever to Big Oil, sees what is happening to the atmosphere as the crucial issue that it is.

In doing so, he has reignited hope around the globe that climate change can be tackled – hope that was badly dented by the eight years of Bush obstructionism. Obama ran for office on a platform that included proper action to deal with it, and now for many people inside the United States and outside, how he does so will be the defining issue of his presidency.

There is broad agreement that what he has to do is two-fold. The first priority is to lead the charge to the low-carbon economy, and build a completely new energy infrastructure that is less and less dependent on fossil fuels – and so enable US carbon dioxide emissions, the highest in the world along with China's, to be slashed. The second priority is to re-engage the US with the international effort to construct a new climate treaty, which will come to a head at the UN climate conference in Copenhagen in December.

He has made a very good start, even as President-elect. He has said the right things: within days of winning the election, he committed the US to a drastic reduction of its CO2 emissions, pledging to cut them back to 80 per cent of 1990 levels by 2050 (Bush made no commitment). And he has appointed the right people: his new senior staff include some of the world's most respected climate scientists and advocates for radical action, such as Professor Steven Chu, the new energy secretary, Professor John Holdren, the new White House chief scientist, and Professor Jane Lubchenco, new head of the National Oceanic and Atmospheric Administration. "These are all people who have climate change as a central part of what they think is crucial," said Eileen Clausen, president of America's leading climate think-tank, the Pew Center.

In terms of substantive policy, President Obama is likely to act at once: climate-related spending, such as a new push for renewable energy, is likely to figure prominently in the economic-stimulus package he is discussing, and American energy suppliers are likely to be given a target of providing 25 per cent of their electricity from renewable sources by 2025. But the key measure to get America's CO2 down will be a national emissions trading scheme along the lines of the one now up and running in the EU. The President will have to get this through Congress: the House of Representatives will be easier than the Senate, where the Democrats do not have the 60 seats out of 100 necessary to override a filibuster, but hopes are high that he will succeed.

Most of all, he has to engage with the rest of the world. There is a massive vacancy for a world leader in the fight to preserve the atmosphere and the habitability of the earth; many people in many countries are fervently hoping that the 44th President is the man who is willing and able to fill it.