Will the Earth burn up, or be inundated by floods, or both, unless drastic and immediate action is taken? Several Democratic Members of Congress think so. In February they introduced a proposal for a “Green New Deal,” a hugely ambitious program for a rapid and steep reduction in the emission of the greenhouse gases that cause the Earth’s temperature to rise. The program includes, among other goals, abolishing the domestic use of all carbon-based fuels—coal, oil, and natural gas—in ten years. In combination with the beginning of the contest for the 2020 Democratic presidential nomination, the candidates for which have already begun to compete with one another in their commitment—in principle if not in all of its particulars—to the program, it has vaulted the issue of climate change to the top of the American political agenda.
The program’s proponents have a propensity for calling climate change an “existential threat” to the well-being not only of all Americans but of all the inhabitants of the planet Earth. They thus suggest that it is a danger on a par with, and perhaps even greater than, past and present threats such as fascism, communism, terrorism, and weapons of mass destruction.
Even if one of the Green New Deal-promoting Democrats manages to become President, however, he or she will not be able to implement the sweeping policies the program advocates. Three formidable barriers to the political consensus required to take the necessary steps stand in the way, each of them built into the problem of climate change: the uncertainties associated with it; the very long time horizon it involves; and the global scope required for an effective response to it.
Climate change is not a hoax. Its geophysical basis has been known for well over 100 years. Greenhouse gases form a kind of blanket in the Earth’s atmosphere, trapping heat and raising the temperature not just of the atmosphere but of its surface and oceans as well. The greater the volume of greenhouse gas emitted, the thicker the blanket becomes and therefore the higher the temperature will rise. In recent decades emissions have soared and recorded temperatures have, in an uneven pattern, increased.
Beyond these basic facts, however, lie considerable uncertainties. It is impossible to know how much greenhouse gas will be emitted in the future. It is not clear precisely how great an increase in temperature a given expansion of the atmospheric blanket will produce. It is even less certain what the geophysical effects will be of whatever temperature increases will occur: scientists envision rising sea levels and more frequent extreme events such as droughts and hurricanes but cannot forecast them with confidence or precision. Less certain still are the social, economic, and political consequences of whatever impact on the planet temperature increases turn out to have.
The predictions that scientists do make are based on the models of the climate that they construct; but it is difficult for them to produce wholly reliable models because the climate is so complicated and because their models incorporate assumptions about a range of physical effects that are almost certainly imprecise and might ultimately prove to be entirely erroneous. This limits the value of the predictions.
Combating climate change will require a measure of economic sacrifice, in the form of higher prices for energy and the many products that energy is used to make and perhaps even, as the Green New Deal suggests, through changes of lifestyle. Summoning taxpayers and voters to make sacrifices is not easy under any circumstances and is all the harder when the harms the sacrifices are designed to avoid cannot be precisely defined or measured.
Given so much uncertainty, it is possible that the disruption that climate change causes will be more modest than the most prominent forecasts foretell. This is not, however, a reason for complacency. Uncertainty, after all, cuts both ways. The impact of whatever temperature increases takes place could equally plausibly turn out to be worse than the predictions that the most widely used climate models have yielded.
Scientists believe that the most serious effects of climate change will not occur for decades. This, too, presents an obstacle to decisive action to curtail it. Prevention requires citizens to make sacrifices now to avoid harm to people they do not and cannot know because the beneficiaries have yet to be born.
It is notoriously difficult to get people to do things in the present that will pay off, even for those same people, in familiar and important ways, in the future: too few save enough for retirement, or get regular medical checkups, or follow healthy diets. It is all the more difficult to persuade them to make what may seem considerable sacrifices in the present on behalf of others not yet living and for vaguer, less familiar purposes.
Moreover, to have a serious impact on climate change, preventive measures must be taken by all the countries that contribute substantially to the Earth’s blanket of greenhouse gas. Even if the United States were to adopt every one of the initiatives that make up the Green New Deal, climate change would remain a serious problem unless China, India, Russia and Europe were to act along similar lines.
The imposition of limits on climate change is an example of what economists call an “international public good.” A public good is something whose benefits cannot be denied to anybody, such as national defense, clean air, and clean water. Public goods are difficult to produce because everyone has an incentive to be a free rider—to avoid paying for them. If all relevant parties act in this way, of course, there is no public good. Within countries this problem is solved by the existence of government, which uses its coercive power to compel citizens to pay through taxation. Since there is no global government, however, this solution is not available for restraining climate change. True, 195 countries have signed the 2015 Paris Climate Accord, whose goal is to stop the rise in the global temperature—although the United States has since withdrawn; but that accord is merely a statement of good intentions. It lacks an enforcement mechanism.
So the Green New Deal, whatever its role in the politics of 2020, will not be implemented—which in turn raises the question of what, if anything, can be done to limit what could, in the worst case, be the catastrophic impact of climate change. As it happens, two useful measures are at least possible politically, as the Green New Deal is not.
One is a tax on greenhouse gas emissions, especially from carbon-based fuels. A large number of economists, from all parts of the political spectrum, favor such a tax. On the well established principle that taxing something yields less of it (while subsidizing it produces more) a tax would reduce such emissions. Americans are notoriously tax-averse (Europeans and Japanese tax gasoline far more heavily, for example) but Democratic presidential candidates have proposed tax increases in order to pay for more generous social welfare benefits and reduce economic inequality in the United States. Whatever the merits of their proposals, a carbon tax would do far more than those they propose to combat what these same candidates declare to be an existential threat.
Such a tax would give individuals and businesses the incentive to find ways to conduct their activities using less carbon-based fuel. A second measure would assist in this effort: increased funding for research and development on technologies that save energy, something that Senator Lamar Alexander, a Tennessee Republican, has proposed and that a number of Democratic presidential candidates support. To be sure, neither measure individually, nor the two of them taken together, would reduce the volume of greenhouse gas emissions as dramatically as the Green New Deal aspires to do. Unlike that program, however, an actual American government might conceivably adopt them.
All this means that the Earth’s greenhouse-gas blanket will very likely continue to thicken, the Earth’s temperature will correspondingly rise, and this will probably have adverse consequences of some kind for the planet’s inhabitants in the decades to come. If the United States and other countries fail to prevent such consequences they will have to adapt to them. Adaptation could prove very costly. If, for example melting ice should cause sea levels to rise by thirty feet, as some estimates foresee, this would require building a very high protective wall around the island of Manhattan or abandoning it altogether.
Whether circumstances will become this dire cannot be known in advance; but it can be asserted with confidence that if and when it does become necessary, adaptation, unlike prevention, will take place: the three major obstacles to prevention will not block it. The effects of climate change will be all too real rather than speculative. The impact will be felt by those living at the time, not by distant future generations. And adaptation will not require the participation of other countries. In fact, other countries surely will not participate. If a great wall of Manhattan has to be built, it is safe to predict, it will be Americans, not Russians, Chinese, Indians or Europeans, who will pay for it.