There is certainly much to talk about at Davos this year. Under a characteristically banal official title – "resilient dynamism" – the five-day World Economic Forum meeting that began tonight will take in such meaty matters as lacklustre global growth, the euro crisis, and the outlook for the Middle East.

So far, so predictable. Less expected – and to be warmly welcomed – are the signs that climate change is heading back up the agenda. About time, too. Policymakers have lost much of their environmental urgency as the exigencies of recession have distracted public attention and a "pause" in the rise of global temperatures has given succour to the sceptical and the complacent. Yet the risks from increasingly unstable weather patterns are more evident than ever, from the unprecedented melt-back of Arctic sea ice, to the devastation wreaked by Hurricane Sandy, to Australian temperatures so high that the Bureau of Meteorologists had to add an extra colour to its heat scale.

Indeed, the WEF's Global Risks report, published in the run-up to Davos, judged the three biggest dangers to world stability to be government debt levels, the growing gap between rich and poor, and rising greenhouse gas emissions. It can only be hoped that so stark an assessment will focus the minds of the 2,500 world leaders, central bankers, business people and lobbyists now gathered at the Swiss mountain resort.

That the UN Secretary General this week ranked climate change alongside the war in Syria as his top priorities will help. As will his stated intention to use Davos to bang the drum for the UN's efforts to tackle global emissions. And if there was any lingering doubt as to what it will take to cut our carbon intensity, it will be dispelled by the Green Growth Action Alliance. The WEF-backed group led by former Mexican President Felipe Calderón estimates that some $14 trillion will need to be spent on low-carbon industry and infrastructure between now and 2030.

Mr Calderón does not pull his punches, warning of "a climate crisis with potentially devastating impacts on the global economy" and, rightly, observing that the upfront investment is a bargain compared with the cost of dealing with extreme weather. His message chimes closely with the priorities of the Davos delegates at whom it is aimed. And the implications could hardly be clearer: there is no time to waste.

It is encouraging, then, that Monday's inauguration speech from Barack Obama also put the environment firmly on the US priority list. The President talked explicitly of the need to "respond to the threat of climate change", stressing both the moral responsibility of protecting the environment and the "new jobs and new industries" that are being established. Rhetoric alone will not be enough; Mr Obama must now act with equal decisiveness. At home, the priority is to get to grips with emissions from power plants and motor vehicles and to significantly boost renewable energy. But there is also a crucial role for the US President on the world stage.

At the UN climate conference in Durban two years ago, there were real advances: the world's three biggest carbon-emitters – China, India and the US – agreed, for the first time, to be bound by the next global treaty. At Doha in November, however, progress was negligible. With just three years left to negotiate the deal, high-profile international leadership would make all the difference. Now is the moment – if only Mr Obama will take it. Perhaps all the talk of climate change emanating from Davos will help focus the President's mind, too.