Whose job is it to stop climate change? For a while, it has seemed like it's up to us, as individuals, to change our personal behavior. Witness the BBC news item this week, exposing Britons' slobby habit of leaving electronic appliances on stand-by, in contrast with the conscientious, energy-efficient Germans. David Cameron's wind turbine on the roof, even his cycling, have fed the notion that greenism is now all about personal conduct.
But we should be careful: climate change is too big a problem to be solved simply by virtuous individuals hopping on a bus instead of taking the car, or disconnecting the tumble dryer, valuable though those moves are. This is one responsibility that can't be saddled solely on activists and consumers. This is a job for government.
Which means governments, no less than individuals, have to rethink their behavior. Until now, governments have tended to dump climate change into the laps of their environment ministries. The odd speech from the president or prime minister, to raise the issue's profile, but otherwise filed under "e" for environment.
That approach is no longer, how shall we put it, sustainable. It should be obvious that climate change is not a discrete policy problem but an across-the-board threat to every aspect of our lives, if not our very survival. Confronted with a planetary emergency, it takes a special kind of bureaucratic myopia to allocate it to a single government ministry.
On Tuesday there were two signs that this penny has at last dropped. The first was word of a new climate change bill, which will create a new body dedicated to following the science on global warming and setting targets on carbon emissions decade by decade.
The second sign was a useful speech by British Foreign Secretary Margaret Beckett. She flew to Berlin to give it (adding to a carbon dioxide cloud of nearly 1,000 tonnes last year and this year alone, thanks to the 10.4 million air kilometers racked up by British Cabinet ministers and their entourages), but we'll put that particular inconvenient truth to one side.
Significantly, this was a speech about climate change delivered not by an environment minister but by the foreign secretary.
"This is not just an environmental problem," she said. "It is a defense problem. It is a problem for those who deal with economics and development, conflict prevention, agriculture, finance, housing, transport, innovation, trade and health."
She's right, with economics the obvious example.
On Monday, former World Bank vice president Sir Nicholas Stern will deliver his report on the economics of climate change, and I'm told his message will be stark. He believes that climate change represents the biggest market failure ever, bigger than the two world wars and the Depression put together. To combat it will cost a huge amount. But Stern will say that it is affordable, if only because a refusal to act will end up costing a whole lot more.
Still, if global warming is inseparable from economics, it casts a similar shadow over foreign policy. John Ashton, who sits as the UK's special representative for climate change within the Foreign Office, reckons that the fires that diplomats spend their lives putting out will only proliferate as the planet heats up. He cites Darfur, where a main cause of conflict has been a shift in rainfall, pitting nomadic herders against settled pastoralists.