Column: What does Trump’s victory mean for climate change policy?

Although he denied it during the presidential debates, it is well known that Donald Trump tweeted in November 2012 that “the concept of global warming was created by and for the Chinese in order to make U.S. manufacturing noncompetitive.” Tweets should hardly be taken as clear and reliable signs of likely public policies, but Mr. Trump followed up during the campaign with his “America First Energy Plan,” in which he pledged to reverse all of President Obama’s actions on climate change.

The plan includes canceling United States participation in the Paris climate agreement and stopping all American funding of United Nations climate change programs. It also includes abandoning the Clean Power Plan, a mainstay of the Obama administration’s approach to achieving its emissions reduction target for carbon dioxide under the Paris agreement.

What should we make of such campaign promises? If we take Mr. Trump at his word, he will seek to pull the country out of the Paris pact. But because the agreement has already come into force, under the rules, any party must wait three years before requesting to withdraw, followed by a one-year notice period. A delightful irony here is that the reason why it came into force so quickly (less than one year after being negotiated in Paris, whereas it took five years for the 1997 Kyoto Protocol to come into effect) is that countries around the world rapidly ratified it to achieve the required threshold, precisely to prevent a possible Trump administration from immediately withdrawing. The United States is now part of the agreement for a minimum of four years.

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In theory, the new administration could try to bypass the four-year delay involved in dropping out of the Paris climate agreement by taking the one-year route of dropping out of the overall United Nations Framework Convention on Climate Change — signed by President George H.W. Bush and ratified by the Senate in 1992. But that would likely require a two-thirds vote of the Senate (the Democrats would filibuster, in any event), would be challenged in the courts and would be unwise in the extreme.

On the other hand, the incoming Trump administration can simply disregard America’s pledge to reduce carbon dioxide emissions by 26 to 28 percent below the 2005 level by 2025. That would be bad enough, but the greater concern is what other key countries, including the world’s largest emitter, China, as well as India and Brazil, will do if the United States reneges on its pledge. The result could be that the Paris agreement unravels, taking it from the 97 percent of global emissions currently covered by the pact to little more than the European Union’s 10 percent share.

In addition, Mr. Trump’s Environmental Protection Agency will probably stop work on regulations of methane emissions (a very potent greenhouse gas) from existing oil and gas operations. Undoing existing regulations, such as the Clean Power Plan, will be more difficult, but a reconstituted Supreme Court will probably help President Trump when that plan inevitably comes before the court. Also, the new president will most likely ask that the Keystone XL pipeline permit application be renewed.

On the campaign trail in North Dakota, Mr. Trump promised to “bring back” the coal industry by cutting environmental regulations. That will not be easy. The decline of that industry and related employment has been caused by technological changes in mining and competition from low-priced natural gas for electricity generation, not by environmental regulations. In Pittsburgh, Mr. Trump pledged to promote fracking for oil and gas, but that would make natural gas even more economically attractive and accelerate the elimination of coal-sector jobs. The inconsistency of these claims — indeed, the internal contradiction — is striking.

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This overall assessment is not optimistic, to put it mildly, so let me close with some good news. First, there are a number of federal “climate change policies” that have been bipartisan and are therefore much less likely to be repealed, such as the latest Corporate Average Fuel Economy standards, which regulate motor vehicle fuel efficiency, appliance efficiency standards as well the recently extended wind and solar tax credits.

Second, there should be little worry at this point about the new president and the new Congress weakening environmental laws, since such attempts would almost certainly be met with a filibuster from Senate Democrats, and the Republicans with their slim 51-48 majority (with one outstanding runoff election) are a substantial distance from a filibuster-proof total of 60 votes.

Third and finally, there are a myriad of subnational climate change policies, ranging from AB-32 in California to the Regional Greenhouse Gas Initiative in the Northeast. It is not a coincidence that there is a high — although not perfect — correlation between these states and those Hillary Clinton won in the election.

Despite this moderately “good news,” the reality is that if he lives up to his campaign rhetoric, Mr. Trump may indeed be able to reverse course on climate change policy, increasing the threat to the planet and in the process destroy much of the Obama legacy in this realm.