Earlier this week, I sketched out what I think is the most plausible outcome for climate policy over the next four years of Donald Trump’s presidency.

To wit: Despite Trump’s regulatory rollbacks, wind and solar power will keep growing, coal will keep declining, and US emissions will dip modestly. But without a big federal policy push, it’s unlikely the US will be on track for the “deep decarbonization” that’s really needed to stop global warming. That task will fall to a future president.

In this post, I’d like to explain why that prediction could very well be wrong! Or at least wildly incomplete.

My starting point is that the evolution of policy, energy markets, and technology can be hugely unpredictable. Not in the hand-wavy sense of “the future’s always unknowable, blah blah.” Rather, over the past 17 years, we’ve seen some monumental surprises in the energy world — ground-shaking court decisions, unexpected swings in coal use, the sudden emergence of new technologies — that have radically revised the climate picture. And it’s a safe bet we’ll see more such shocks in the Trump era.

“You have to remember that presidents don’t entirely control their own agenda,” says Paul Sabin, an environmental historian at Yale University. “They often get shaped by external events that are tough to predict ahead of time.”

A lot of the commentary around Trump and global warming hasn’t wrestled with this deep uncertainty. So let’s wrestle a bit. Down below, I’ll offer some thoughts on what sorts of climate/energy surprises we may see under Trump, though obviously this is ground for endless argument and I'd love to hear from readers on this.

Many of the biggest climate developments of the past 17 years were major shocks

Before getting to the predictions, it’s instructive to think back on George W. Bush. In 2001, Bush entered the White House and announced he’d withdraw from the Kyoto Protocol — the main global climate treaty at the time — and double down on fossil fuels domestically. (Remember Dick Cheney’s Energy Task Force?) It looked for all the world like the US was turning its back on climate action … and that’s mostly how it played out for the next eight years.

But there were also some huge, consequential plot twists along the way. Like:

Unexpected policy swings: By the mid-2000s, China’s rapid growth had sent global oil prices soaring to unbelievable new highs, which jumbled energy politics and spurred Congress to pass strict new fuel economy rules for cars and SUVs (plus biofuel incentives). Then in 2007, states like Massachusetts and California sued the Environmental Protection Agency over Bush’s inaction on global warming — and, shockingly, won. The Supreme Court’s decision paved the way for the EPA to start regulating greenhouse gases.

Those two twists, which were totally unforeseen when Bush entered office, ended up giving the Obama administration two of its most powerful tools for tackling carbon pollution.

The surprising decline of US coal. Meanwhile, technology was evolving in unexpected ways. In the 1990s, George Mitchell was tinkering with hydraulic fracturing techniques to extract natural gas from underground shale rock formations in Texas, which had long been thought inaccessible. By the late 2000s, motivated by high oil prices, a lot of companies were combining hydraulic fracturing with horizontal drilling to pull up enormous amounts of shale gas, and later crude oil, in Texas, Pennsylvania, Ohio, North Dakota, and elsewhere.

Around the same time, the (unexpected) financial crisis in 2008 led Congress to pass a major economic stimulus bill that happened to extend and expand key tax credits for wind and solar power. Those credits, combined with state renewable policies that had grown under Bush and a frenzy of Chinese silicon manufacturing, helped accelerate the growth of wind and solar in the United States.

This fracking and renewables boom revolutionized US electricity markets. The availability of cheap natural gas helped bolster the Sierra Club’s campaign to block the hundreds of new coal plants that were being planned around the country under Bush. By 2016, coal was getting absolutely crushed, and US carbon dioxide emissions from energy had fallen to their lowest levels since 1991. In many states, the growth of rooftop solar is now scrambling utility business models.

China kept defying forecasts. In the early 2000s, China defied the predictions of energy forecasters by going on an unprecedented coal binge, persuading many climate scientists that we were on track for the worst-case climate projections. But then China stunned (many) experts again in 2015 when its coal use suddenly flattened out and started declining far ahead of predictions. That reversal, along with the recent slowdown in global coal use, has helped convince many onlookers that we might be able to stave off the most dire global warming scenarios after all.

Those legal, economic, and technological forces all blended together in complex ways. The US clean energy surge, plus new EPA rules, gave the Obama administration room to announce ambitious goals for reducing US emissions. That, in turn, helped the White House break a longstanding deadlock with China over climate policy. And that, in turn, set the foundation for the Paris climate treaty — which, for all its flaws, seems to represent a new and promising advance over the old Kyoto Protocol that Bush rejected, much to everyone’s consternation in 2001.

Certainly there were prescient experts who saw some of these trends unfolding. But very few people predicted all of these things coming together the way they did even 10 years ago — and these were developments that drastically reshaped the climate and energy landscape. That should instill some humility about forecasting what’s next.

So what climate surprises could the Trump era have in store for us?

Sadly, I can’t predict the future. But that capsule history of the past 17 years does offer clues about what types of surprises we could see in the Trump era — legal, economic, technological, political. I’ll throw out six possibilities, though this list is hardly exhaustive:

1) New technology shifts the energy landscape. Much as fracking did in the 2000s, we could see the emergence of new clean technologies that forcibly shift our emissions trajectory and make the climate challenge feel less dire. Dirt-cheap batteries that upend the economics of electric cars are one possibility. Or perhaps Net Power’s scheme for a gas plant in Texas that can cheaply bury its emissions will prove game-changing. Or maybe scientists tinkering with CRISPR will develop some revolutionary biofuel-making yeasts. Maybe perovskites will usher in an era of breathtakingly low-cost solar power. Maybe rapid changes in utility models will lead to tectonic shifts in the electricity sector. Dream big!

2) A stunning court decision spurs fresh government action. The Supreme Court’s 2007 decision in Massachusetts v. EPA marked a sea change in US climate policy: The EPA is now a major player in CO2 regulation, even after Trump’s efforts to rein it in. Are there more landmark decisions lurking? Perhaps the courts will swat down Trump’s attempts to repeal climate regs. Or: Right now 21 children are suing the feds over climate inaction — on the off chance they prevail, the government may face new obligations to act. Or: If Congress were to repeal the EPA’s ability to regulate greenhouse gases, that could trigger a wave of common law suits against polluters.

3) A high-profile disaster upends energy politics. As Sabin told me, the history of energy and environmental policy is a history of industrial accidents and disasters. The Santa Barbara oil spill of 1969 birthed the modern US environmental movement. Conversely, the Deepwater Horizon oil spill in 2010 helped scuttle a major cap-and-trade bill in the Senate. And the 2011 reactor meltdown at Fukushima put a major crimp on the use of nuclear power as a climate tool worldwide.

It’s quite possible a disaster will jumble energy politics in the Trump era in an unexpected way. Maybe some big shale gas disaster leads to a widespread push to ban fracking (which could help Trump achieve his dream of bringing back coal). Or there’s a big oil spill or pipeline leak that bolsters activism. Or maybe there’s some weather disaster that somehow shifts public opinion on climate change.

4) Oil markets go haywire. For the past few years, oil prices have been fairly low, leading to a resurgence of SUVs and road trips and hindering the growth of electric vehicles. But oil markets are notoriously hard to predict. Conflict in the Middle East, faster-than-expected declines in Russia’s fields, a state-led push to restrict fracking in the United States — it’s not impossible to imagine a future spike in oil prices. And, historically, such spikes have led to major changes in US energy policy.

5) India defies all predictions on coal. India, home to 1.2 billion people, remains one of the biggest climate wild cards. It’s still a very poor country, and it hasn’t gone through the same phase of coal-fueled industrial development that China did over the past few decades. Scenarios for avoiding drastic climate change usually envision India finding a cleaner path than China did. So … will it? Right now the Indian government is projecting that it will halt building coal plants by 2022 and pursue renewables much more heavily. And regulatory dysfunction is hampering coal’s expansion. But how sure are we that that dynamic will persist? As recent Chinese history shows, forecasts are always uncertain, in both directions.

6) Trump changes his mind on climate — or at least does something unexpected. This one doesn’t seem terribly likely. But then again, Sabin notes, Ronald Reagan came into office in 1981 planning to smash the EPA. Within a few years, he faced a huge backlash and turned to more moderate environmental appointees. He ended his tenure by signing the Montreal Protocol to phase out CFCs and save the ozone layer (albeit after much foot dragging and pressure), a treaty that proved a major success story.

That’s not to say Reagan was really an environmentalist, or that Trump will be either. Far from it. Presidents mostly do what they say they’ll do. But history is also full of intriguing wrinkles. The future will be too.

Further reading: