President-elect Donald Trump announced he will nominate ExxonMobil chief executive Rex Tillerson as Secretary of State.

Tillerson’s nomination makes him the first —and thus far, only— cabinet pick who does not reject climate change science and embraces a free enterprise solution to the matter. As CEO, he led Exxon away from a position of climate skepticism, supported a climate tax, and praised the Paris climate agreement.

In a speech in October, Tillerson said ExxonMobile “share[s] the view that the risks of climate change are serious and warrant thoughtful action. Addressing these risks requires broad-based, practical solutions around the world. Importantly, as a result of the Paris agreement, both developed and developing countries are now working together to mitigate greenhouse gas emissions, while recognizing differing national responsibilities, capacities and circumstances.” He went on to stress the importance of encouraging “long-term investments in both proven and new technologies, while supporting effective policies.”

Under Tillerson, Exxon “long supported a carbon tax as the best policy” on the table for reducing carbon emissions. “Replacing the hodge-podge of current, largely ineffective regulations with a revenue-neutral carbon tax would ensure a uniform and predictable cost of carbon across the economy. It would allow market forces to drive solutions. It would maximize transparency, reduce administrative complexity, promote global participation and easily adjust to future developments in our understanding of climate science as well as the policy consequences of these actions.”

Tillerson faces a tough nomination process in the U.S. Senate.