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It’s not exactly news that Donald Trump’s election as president signals a drastic shift in U.S. environmental policy, but there may be more than meets the eye initially.

Trump has called climate change a “hoax,” and railed against economic impacts of environmental regulation at the national and international level. He has indicated he will pull the U.S. out of the Paris Agreement climate change pact, kill President Obama’s Clean Power Plan for the electricity sector and increase output of coal and oil. Potential appointees for major cabinet positions such as Secretary of Energy and Administrator of the Environmental Protection Agency include fossil fuel industry lobbyists and climate change denialists.

However, the president-elect has also emphasized the importance of maintaining clean air and water, and has stated support for the U.S. Environmental Protection Agency as a tool for “ensuring clean air, and clean, safe drinking water for all Americans.” A Trump website declares an intention to gain energy independence for the U.S. by using a range of sources, including renewable energy.

Stanford experts in law, economics, energy and climate change discussed the likely environmental impacts of a Trump presidency.

What could the election mean for U.S. commitments to national and international environmental agreements?

Charles Kolstad: Trying to figure out what Donald Trump may pursue unilaterally or with the Republican Congress is not easy and it depends on whether Trump will choose to serve narrow Republican interest groups, the percentage of the electorate that voted for him or pursue actions that have broader support. If we assume that he will focus on a larger slice of the electorate than his base, he may focus on streamlining regulation rather than tackling the difficult task of eliminating environmental protection. A potential move in this direction would be to institute a revenue-neutral carbon tax in exchange for scrapping the Clean Power Plan. The revenue from the carbon tax could be used to reduce the payroll tax, which hits a lot of his rural constituents hard. There is Republican support for a revenue-neutral carbon tax. One problem is that Trump has promised to save the U.S. coal industry. That is not very feasible. Wall Street has already pronounced investment in coal combustion risky.

John Weyant: The current, non-legally binding U.S. commitment to the Paris Agreement does not technically expire for three years and then requires a year of advance notice to withdraw it. He could just delay or weaken actual policies during that time, but he probably won’t care. He could also, with only one-year notice, drop out of the United Nations Framework Convention on Climate Change signed by President George H.W. Bush and ratified by the U.S. Senate in 1992. The biggest impact of any of these things is that it may cause other major emitting countries to reduce their commitments. Trump can probably undo the executive order-driven Clean Power Plan commitments, but the courts have already required the Environmental Protection Agency to regulate greenhouse gasses under the Clean Air Act, so it may go back to the EPA for another try. Of course, it could be sent back to the Supreme Court, especially if Trump has appointed a justice who will reverse the earlier decision. This would be time-consuming to coordinate, so it is more likely he will just try to delay doing anything as long as possible.

Chris Field and Katharine Mach: Trump has spoken about the importance of protecting the environment, but he has also consistently indicated that he would cancel any environmental regulations or withdraw the U.S. from any international agreements that are bad for U.S. interests. If he looks closely at the evidence, he will find that that the overwhelming majority of environmental regulations, both nationally and internationally, are good for U.S. interests and good for the world. Some might be improved through better monitoring or implementation. But overall, a clean, sustainable environment is a huge asset for everyone. If we take Mr. Trump at his word that he wants regulations that truly protect the environment, we need stronger, not weaker environmental protection.

Does a Trump presidency suggest any surprises in terms of environmental regulation or diplomacy?

Rob Jackson: One interesting question is how much international pressure we’ll face if we withdraw from the Paris accord. Will countries and companies face pressure to boycott U.S. goods and services? The court of public opinion can be a strong motivator for business.

Kolstad: It could be a repeat of the Reagan and Bush years with the environmental community hunkering down. But it may be like the George H.W. Bush years, in which major steps were taken to streamline environmental regulation. This showed we can have a better environment without as much bureaucracy and burdensome regulation. The Clean Air Act Amendments of 1990 were promoted by Bush the elder. That initiative ended a decade of squabbling over acid rain. It also was the beginning of the highly successful cap-and-trade program for sulfur emissions, which was the model for the European Carbon Trading System.

Deborah Sivas: What I fervently hope is that some of those with expertise in environmental and energy issues can find a way to talk with the Trump team about the real facts of what is at stake and how his jobs rhetoric can actually be synchronized with, for example, a robust renewable energy strategy. There is a way to talk about these issues that aligns with some of the Trump message, although not necessarily with the fossil-fuel industry that has the ear of traditional Republicans. For example, the big utilities, protected by state public utility commissions, are essentially the establishment fighting to preserve their monopolies. Breaking that entrenched business model would open up opportunities for a new path forward and a new way of doing business that fosters economic prosperity.

Weyant: Trump will probably learn that energy and, potentially, climate change can have critical national security dimensions, so he may be motivated to move a bit more on those accounts.

Noah Diffenbaugh: Trump has emphasized investment in infrastructure, including in his acceptance speech this week. Most of our infrastructure – including our water and transportation infrastructure here in California – was designed and built in an old climate, and emphasized a fossil-fuel-based economy. Serious investments in revitalizing our nation’s infrastructure with a focus on efficiency, resiliency and adaptability could have major benefits for both reducing greenhouse gas emissions and increasing resilience to climate stresses now and in the future.

How might the U.S. Environmental Protection Agency be affected by a President Trump?

Sivas: Given the campaign rhetoric and the extreme partisan nature of environmental issues, my best guess is that we are looking at something like the Anne Gorsuch days, when EPA management under President Reagan set about to defund, delegitimize and demoralize the agency. I am telling some of our despairing students not to give up on government. We need good, smart people in government agencies. If our best and brightest students walk away from government opportunities, which are admittedly challenging in times like these, there is little hope that we will have smart, thoughtful people trying to shape environmental policies. That’s a national tragedy in the making.

How likely is the Keystone XL Pipeline to be resurrected?

Sivas: My guess is very likely. If nothing else, this is an easy target where there is little daylight between Trump’s rural blue-collar supporters and the Republican Party establishment. And the president can act quickly on his own. So I would expect to see action on this early, as a down payment on campaign promises by Trump, who is going to have a much harder time on some of his other trade and jobs issues. And then expect to see lawsuits in response.

Jackson: The bulldozers are already firing up, and lawyers on both sides are smiling.

Kolstad: The low price of oil means that approval of the Keystone XL Pipeline is moot – it is unlikely to be built anytime soon anyway.

Noah Diffenbaugh is a professor of Earth system science in the School of Earth, Energy & Environmental Sciences and a senior fellow at the Stanford Woods Institute for the Environment.

Chris Field is the Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies, director of the Stanford Woods Institute for the Environment, professor of Earth system science and of biology and a senior fellow the Precourt Institute for Energy.

Rob Jackson is the Michelle and Kevin Douglas Provostial Professor, a professor of Earth system science in the School of Earth, Energy & Environmental Sciences, and a senior fellow at the Stanford Woods Institute for the Environment and at the Precourt Institute for Energy.

Charles Kolstad is a senior fellow at the Precourt Institute for Energy and at the Stanford Institute for Economic Policy Research.

Katharine Mach is senior research scientist in the Department of Earth System Science and the director of the Stanford Environment Assessment Facility.

Deborah Sivas is the Luke W. Cole Professor of Environmental Law, director of the Environmental Law Clinic and director of the Environmental and Natural Resources Law and Policy Program at Stanford Law School. She is also a senior fellow at the Stanford Woods Institute for the Environment.

John Weyant is a professor (research) of management science and engineering, director of the Energy Modeling Forum and deputy director of the Precourt Institute for Energy Efficiency.