The latest appointments to Barack Obama's administration are significant for a host of reasons. But perhaps most significant is what they tell us about the environmental priorities of the incoming American President: Mr Obama is deadly serious about facing up to the challenge of climate change.
At the weekend, the President-elect appointed two of the world's most respected climate scientists, John Holdren and Jane Lubchenco, to his team as scientific adviser and head of the National Oceanic and Atmospheric Administration respectively. Both are advocates of urgent action to curtail global warming.
They will join the incoming Energy Secretary, Steven Chu, who is another prominent advocate of the need to tackle climate change, and the Labour Secretary, Hilda Solis, who sponsored a Green Jobs Act in Congress last year.
Several of Mr Obama's team appointments reflected a spirit of compromise (Hillary Clinton as Secretary of State) and bipartisanship (Robert Gates to remain as Defence Secretary). There will be intense disagreement when it comes to foreign policy. But on matters touching the environment there will be consensus. Mr Obama's team is united in the belief that climate change is a serious danger and demands co-ordinated action from national governments to counter it. After the denial and wrecking tactics of the Bush Administration that will be a relief.
But what will the new administration's environmental orientation mean in practical terms? Some expect Mr Obama's anticipated fiscal stimulus package to include a heavy emphasis on creating green jobs. The prospects of a breakthrough deal on global emission reductions in Copenhagen next year also look brighter.
There is, of course, only so much one nation can do in the face of a threat like global warming, even the US. A huge amount will depend on the willingness of rapidly industrialising nations such as China and India to reform too. But Mr Obama has unquestionably laid down a signal of intent: the struggle against runaway climate change will now enjoy the full-hearted support of the leader of the most powerful nation on the planet. That is a change we all need.