How can we seriously tackle climate change when one of the biggest barriers to reducing emissions is sitting in the White House?

We have no choice but to press on, but without the cooperation of countries such as the US and China, the rate of global warming won’t slow down fast enough to make a difference

Economists call it the “tragedy of the commons” – the tendency for human beings to trash their common resources. It can be witnessed anywhere from the vandalism and neglect of the “common parts” of blocks of flats, to the destruction of cod stocks in the Atlantic through overfishing.

It is appropriate that, on the day the UN Intergovernmental Panel on Climate Change (IPCC) issued a further urgent warning on global warming, the Nobel Prize in Economics has been awarded to Paul Romer and William Nordhaus, whose work tries to deal with this very problem on a planetary scale. Economic insight, technology and political will are the best weapons at our disposal.

The ultimate tragedy of the ultimate commons is, of course, the despoliation of planet earth by its inhabitants. All, or at least many, individually, of the earth’s inhabitants may accept the case for controlling emissions and limiting pollution, but this broad consensus, such as it is, seems insufficient to change either individual behaviour or national policies decisively.

The risks are too remote in time for many to comprehend; the citizens of richer nations seem complacent, indeed misguided, about their immunity from the effects of climate change and, closely related to that, are ignorant of the economic, social and political changes that such dramatic trends will give rise to. Some “just about managing” family in Bolton or Bologna may not immediately be alarmed that the Maldives are about to go under water.

Some of that may be down to that other economic law – of diminishing returns. As the warnings about climate change grow ever more shrill – and understandably so – they seem to have less and less impact. Populations may be growing to feel that the task of saving the planet is for superheroes, and is simply so awesome that they almost give up. As Mr Romer explains: “Once we start to try to reduce carbon emissions, we’ll be surprised that it wasn’t as hard as we anticipated. The danger with very alarming forecasts is that it will make people feel apathetic and hopeless.”

There is a lesson there for the west’s politicians – to convert the abstract scientific language into something that their voters can understand and feel they can actually make a difference about.

The IPCC, though, has no choice other than to be extremely clear about what is happening to the climate – as scientists have been for decades now, with disappointing results. We are already headed for an environmental disaster with an apparently unavoidable rise in global temperatures of 1.5C by the end of this century. That in itself will eliminate one in 20 insect species, for example, raise sea levels and destroy 90 per cent of the coral reefs on earth.

The precise consequences of that are incalculable, but need not be abstract, and will not be confined to non-human species. What will the impact on crops if there are fewer insects to pollinate them? On forced migration of large populations from, say, the Indian subcontinent as a result of rising sea levels drowning Bangladesh, and loss of drinking water? What will that do for international peace and security? It is difficult to imagine that Europe, Asia and North America, the major engines of climate change, will escape unscathed from such dislocations.

If nothing is done, then that disaster, terrifying as it is, will actually be as good as it gets, because limiting the rise in temperatures to 1.5C is the least that the world will get away with now. If even less is done, and temperatures rise by 2 or 3 per cent or more, then the future of the human species on this fragile chunk of rock seems bleak indeed.

Of course, things have been done. The world has not slept. Since the Rio summit and Kyoto protocol in the 1990s, many countries have taken action to limit CO2 emissions, and act on other issues such as plastic pollution. Technology has delivered us leaps forward in electric cars, renewable energy, recycling and ever-more energy efficient homes, appliances, offices and factories.

Vegetarianism and veganism will also, perhaps, make a substantial impact in time. Crucially, China seems to have undergone a dramatic alteration in official attitudes, under its grey, polluted skies. The global climate of opinion is changing, albeit more slowly than the climate of the planet.

The Paris climate change agreement, signed only in 2016, was moment of tremendous hope for the whole planet, a time when almost every nation on earth did come together and agreed that the common shared future of humankind was greater than the short-term interest of any economy, large or small. By no means perfect, the agreement was at least a workable plan, the effects of which would save lives, prevent wars and achieve nothing less than the remaining habitability of every continent.

Then came Donald Trump. Despite intense diplomatic pressure, not least by the supposed “Trump-whisperer” President Emmanuel Macron of France, America has withdrawn from the agreement. Perhaps one day a sane, decent president will be elected by an American people increasingly spooked by the freakish weather that is disturbing their lives, agriculture and energy supplies.

There is some cause for optimism that the Trump era will eventually pass, and that in the meantime progressive individual states such as California can mitigate the most noxious effects of this American exceptionalism. Still, the fracking will go on.

Either way, the rest of the world has no choice but to press on, and to do even more given that the world’s largest economy has opted out of its global responsibilities – as it increasingly seems ready to do. It is unfair, it is perhaps politically impossible, and it certainly makes the task of revolutionising energy, industry, agriculture and transportation that much harder. Yet the rest of us have no alternative.

The media also bears a responsibility here. “Balance” does not mean that some jokey journalist or unqualified politician with a dismissive line about polar bears or a heavy night of snow should be granted the same weight and credibility as almost the entire scientific community. Cranks are entitled to their point of view, and to express it freely; but, like flat-Earthers or creationists, they have no right to be believed.

The largest single obstacle to saving the planet’s ecology sits in the White House. So many times in the past America has saved the world; now the moment has come when the rest of the world will need to make many sacrifices to save itself and America. A tragedy indeed.