The catastrophic outcome of last November's United States presidential election is now clear. President Donald Trump's indifference to the risk of climate change, and the actions he is taking because of that indifference, are likely to have consequences that dwarf the significance of his executive order on immigration, his nomination of an arch-conservative to the Supreme Court, and, should he manage to achieve it, his repeal of the Affordable Care Act ("Obamacare").
With the exception of launching a nuclear war, it is hard to think of anything a US president could do that is liable to harm more people than last month's order cancelling rules issued under former president Barack Obama to freeze the construction of new coal-fired power plants and shut down many old ones. Mr Trump's order followed his pledge to rescind stricter fuel-efficiency standards for cars and trucks, and his announcement that he wants to slash spending on climate science.
Although Mr Trump did not announce the withdrawal of the US from the Paris climate agreement, his actions are likely to prove incompatible with the US government's pledge to reduce greenhouse-gas emissions to 26% below 2005 levels by 2025. The Paris agreement, signed by 195 countries, is our last real chance of keeping global warming to less than 2 degrees Celsius above pre-industrial levels. Even 2ºC is too much for the inhabitants of low-lying island states. Many of these states were pleading for a 1.5ºC limit -- without which some will disappear beneath the ocean.
Any increase in global temperature greater than 2ºC, scientists agree, risks triggering feedback loops that cause much greater warming and could render large parts of the planet uninhabitable. For example, further warming would release large quantities of methane -- a more potent greenhouse gas than carbon dioxide -- from thawing Siberian permafrost, leading to more warming, more thawing, and more methane in the atmosphere. Similarly, warming causes the loss of arctic ice, which means that less of the sun's heat is reflected back rather than being absorbed by the ocean.
During the election campaign, Mr Trump described climate change as a "hoax" perpetrated by the Chinese to destroy American industry. Last month, Scott Pruitt, Mr Trump's appointee to head the Environmental Protection Agency, said that he did not believe that CO2 is the primary contributor to climate change. He added that "we do not know that yet," and "we need to continue the review and analysis."
The American Meteorological Society promptly wrote to Mr Pruitt saying that it is "indisputable" that CO2 and other greenhouse gases are the primary cause of global warming, and that it is "not familiar with any scientific institution with relevant subject matter expertise that has reached a different conclusion."
That is true. What many commentators failed to notice, however, is that even if, contrary to all the evidence, we were to accept Mr Pruitt's statement that "we do not know" whether CO2 is the primary contributor to climate change, the Trump administration's actions would still be reckless. Unless the probability that CO2 is the primary contributor to climate change is very small, it is wrong to take chances with the future of our planet and the lives of hundreds of millions of people in order to reduce energy costs for Americans and preserve a few thousand jobs in the coal industry. (In fact, coal jobs are disappearing because of automation and competition from cheaper natural gas, not because of regulations to reduce CO2 emissions.)
Perhaps, though, Mr Trump does not see his policy as reckless because, as he has repeatedly proclaimed, he puts "America first." And it is indeed America between now and the next election that he puts first, at the expense of Americans' longer-term interests and the interests of everyone who is not American.
In the short term, those who will suffer most from climate change are not Americans, but people living in tropical latitudes, and especially the poor, who will have nowhere to go when rains fail or the heat parches their crops. When sea levels rise, those island-state inhabitants, living just a metre or two above sea level, will be the first to be driven off their land, followed by tens of millions of people farming small plots in fertile delta regions in Bangladesh, Southeast Asia, and Egypt.
The Paris climate agreement has no mechanism for sanctioning countries that fail to fulfill their pledges. The idea is that such countries will be "named and shamed." Well before Mr Trump was elected president it was obvious that he is immune to shame. What, then, can other countries, and individuals, whether in the US or beyond its borders, do about the fact that Mr Trump is jeopardising our future?
If the US uses the cheapest available fuels to produce energy, irrespective of the harm that burning those fuels does to others, it is giving its companies an unfair advantage over those that are trying to meet their Paris pledges. That should be enough for the World Trade Organisation to allow other countries to erect trade barriers against US goods. Otherwise, the remedy is in the hands of foreign consumers, who can show their opposition by choosing to not to buy American.
A boycott is a blunt instrument that would, regrettably, harm many US workers who did not vote for Mr Trump and are in no way responsible for his policies. But with so much at stake, and such limited means of changing Mr Trump's policies, what else is there to do? ©2017 PROJECT SYNDICATE