Todd Stern, a visiting lecturer at Yale Law School, was U.S. special envoy for climate change from 2009 to 2016.

As President Trump takes the reins of power, anxiety and uncertainty are the order of the day for those concerned about the threat of climate change. Trump has ranged from disbelieving (climate change is a Chinese “hoax”) to dismissive (we should “cancel” the 2015 Paris agreement) to open (“I’m looking at it very closely. . . . I have an open mind to it”) on the issue.

The truth is that the climate challenge Trump faces is large and the stakes are high, but he has been dealt a very good hand if he is willing to play it.

The challenge is that achieving the climate goals endorsed by all the countries in Paris — especially holding the increase in global average temperature to well below 2 degrees Celsius compared with preindustrial levels — will take a concerted commitment centered on rapidly transitioning from a high- to a very-low-carbon global energy system. A global economy that currently runs more than 80 percent on fossil fuels will have to cut that habit dramatically by 2050 and eliminate or capture all carbon emissions by the 2060s or 2070s.

Nor can the Paris goals be shrugged off as an excess of zeal that we can comfortably revise upward. With average temperature having risen by only 0.9 degrees Celsius so far, we already see rapidly accumulating evidence of rising sea levels, stressed water supplies and “100-year” events such as extreme droughts, floods and storms. As these and other effects worsen, we will face risks to health, safety, economic well-being and national security that we have never tolerated in any other context. If you doubt this, just consult the published views of the Pentagon, the intelligence community and any number of major corporations, not to mention the leading lights of the U.S. and global scientific establishment.

The good news, though, is that while meeting the challenge of transitioning to clean energy is formidable, it is also doable as a matter of innovation, policy and financing. We know what we need to do, and we can do it — if the political will is there.

Which brings us back to Trump and those good cards he has been dealt. First, he has the Paris agreement itself. Climate change is a global problem, so it can’t be solved without a global regime to drive joint action, and the landmark Paris accord finally delivered that regime, after 20 years of trying. It is built to work both for the United States and for others. It has a bottom-up structure based on countries devising their own climate plans and targets; it applies to all, including China and India; it renews itself every five years as countries update and augment the ambition of their efforts; and it includes binding commitments for full transparency, so all countries can have confidence that others are acting.

(Daron Taylor/The Washington Post)

Second, we have entered a period of explosive growth in clean energy, led by the genius of U.S. innovation both in technology and in business models, and by the massive markets being created worldwide for pollution-free energy. The costs of wind and solar generation have been plummeting and are already near the cost of fossil fuel, and sometimes cheaper. More than 60 percent of new electricity capacity in the United States in the past two years has come from these sources.

And innovation is blossoming all over the clean-tech landscape, from storage technology to open the door for expanding use of renewables, to electric vehicles, to a smarter grid that will enable more work to be done with less energy.

Plus, there are jobs — for example, more solar jobs now in the United States than in the oil, gas and coal extraction industries combined. And clean energy is hugely popular with both Democratic and Republican voters.

We still, crucially, need strong policy support and research and development, but the change is gathering speed.

Globally, the economic potential of the clean-energy transition is staggering, amounting to trillions of dollars. No one has more to gain than the United States by jumping into this new “great race” with both feet, given our unparalleled culture and infrastructure of innovation. It’s the deal of the century, and a presidential dealmaker should pursue it with gusto.

None of this would prevent generous treatment for those, such as coal miners, who helped build the industrial backbone of our nation. Or, indeed, for full-on R&D and other support for technologies such as carbon capture and storage.

Is it plausible that Trump could recognize the climate challenge and embrace this opportunity? The key lies in that “open mind” of his. If it is open, then he will listen to knowledgeable advisers — from the military, big business, Wall Street, the scientific community — and he’ll come quickly to understand the risk of climate change and the reward of taking it on.

With an open mind, Trump can make history. He has a Nixon-to-China capacity to bring Congress, the American public and the rest of the world with him on climate. He should seize it.