President-elect Donald Trump's nominee for secretary of state, Rex Tillerson, said he believes the risks of climate change "could be serious enough that action should be taken," but he did not elaborate on what that action should be. (Reuters)

Secretary of state nominee Rex Tillerson on Wednesday said he believes “the risk of climate change does exist, and the consequences could be serious enough that action should be taken.” But while the Obama administration and other world leaders have aggressively pursued efforts to slash carbon dioxide emissions and stave off global warming, the former ExxonMobil chief executive expressed little such urgency when testifying before the Senate Foreign Relations Committee on Capitol Hill Wednesday.

Asked by Sen. Bob Corker (R-Tenn.) about his personal position on climate change, Tillerson said he formed his views “over about 20 years as an engineer and a scientist, understanding the evolution of the science.” Ultimately, he said, he concluded that increasing greenhouse-gas concentrations in the atmosphere are having an effect on the earth’s climate. But he added, “Our ability to predict that effect is very limited,” and precisely what actions nations should take “seems to be the largest area of debate existing in the public discourse.”

Tillerson’s statements on climate change were in line with views he has expressed in the past: In short, that climate change is real and could pose problems for humans, but the degree of threat remains unclear. Tillerson sees climate change primarily through the eyes of an engineer, as something that must be solved largely through innovation and ingenuity.

Scientists, though, would dispute his claim that we have a “very limited” ability to predict what is happening to the planet’s climate due to our emissions — it is warming, and unless action is taken will warm well beyond 2 degrees Celsius above pre-industrial levels. And they’d also dispute his refusal at the hearing to firmly link climate warming to specific weather events, an area where the research is becoming increasingly clear that some attributions are possible, in a statistical or risk-based way.

At another moment, he said that when it comes to climate change, “I don’t see it as the imminent national security threat that perhaps others do.”

Tillerson shared his views — which run counter to President-elect Donald Trump’s brazen skepticism, but also fall far short of a cry of urgency — in multiple segments of questioning as the subject surfaced repeatedly during his lengthy confirmation hearing on Wednesday. And the answers matter greatly because as Secretary of State, he’d head up the U.S.’s engagement, or, its disengagement, in the United Nations climate negotiations that led to the Paris climate agreement.

At one point, Tillerson had a testy exchange with Sen. Tim Kaine (D-Va.), the former vice presidential candidate, about whether ExxonMobil had for decades concealed from investors and the public what it knew about the science of climate change — going as far as paying outside groups, Kaine said, to raise doubts about the growing scientific consensus around the problem.

“I’m in no position to speak” on behalf of company executives, Tillerson said, dodging the senator’s questions about the company where he worked for 40 years. “You would have to speak to them.”

Kaine continued to press Tillerson about his knowledge of ExxonMobil’s history on climate change. Tillerson continued to refer him to the company he led until recently.

At one point, Kaine asked, “Do you lack the knowledge to answer my question, or are you refusing to do so?”

“A little of both,” Tillerson responded.

Kaine later tweeted, “It’s shameful Tillerson refused to answer my questions on his company’s role in funding phony climate science. Bottom line: #ExxonKnew.”

Early in the hearing, Sen. Ben Cardin (D-Md.) asked Tillerson if he thought the United States should continue to play a leading role in a global climate agreement signed in Paris in late 2015. Trump has vowed to “cancel” U.S. participation in the accord, in which hundreds of countries collectively agreed to slash carbon emissions to help mitigate the effects of global warming.

“It’s important that the U.S. maintains its seat at the table about how to address the threat of climate change, which does require a global response,” Tillerson said. “No one country is going to solve this on its own.”

It was a brief exchange, with little new information about how the incoming administration might actually approach the issue. But Tillerson said multiple times Wednesday that the incoming president, who in the past has called climate change a “hoax,” had solicited his opinion on the subject.

“The president-elect has invited my views on climate change, and he has asked for them, and he knows that I am on the public record with my views,” Tillerson said. “And I look forward to providing those, if confirmed, to him, and in discussion around how the U.S. should conduct its policies in this area.”

Ultimately, Tillerson said, he would carry out the new president’s policies, “but I think it’s important to note that he has asked, and I feel free to express those views.”

Sen. Edward Markey (D-Mass.) also pressed on whether the United States would continue to be a primary player in the Paris accord. Tillerson echoed Trump’s position that any international agreement would above all need to benefit the United States.

“I’m sure that there will be opportunity…to do a fulsome review of our policies around engagement on climate issues through global accords, global agreements,” he said. “I also know the president as part of his priority in campaigning was America first. So there’s important considerations…as we commit to those accords, are there any elements of that that put America to a disadvantage?”

“While Tillerson is admitting the role of greenhouse gas emissions in causing climate change, his circumlocutions about climate policy and the Paris agreement so far leave the impression that as Secretary of State he will be somewhere to the right of Exxon on these key issues,” said Paul Bledsoe, a former Senate staff member and Clinton White House adviser, of the performance.

In the past, Tillerson has articulated a more nuanced position on climate change than other Trump cabinet nominees. He repeatedly has acknowledged the potential consequences of climate change and the impact of CO2 emissions in the atmosphere, but has questioned the reliability of climate models and suggested humanity has bigger problems to tackle.

Still, Tillerson and ExxonMobil generally have supported the Paris climate accord in the past, calling it an important international framework for tackling the problem.

“At ExxonMobil, we share 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,” he said in a speech last year in Abu Dhabi. “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. The best hope for the future is to enable and encourage long-term investments in both proven and new technologies, while supporting effective policies.”

That’s a far different position than that of Tillerson’s predecessor at ExxonMobil, Lee Raymond. On the Charlie Rose show in 2005, for instance, Raymond said “natural variability” could affect climate and said the science wasn’t sufficient to determine whether climate changes amount to anything more than that. Such statements help explain why many scientists and environmentalists have continued to criticize ExxonMobil’s past record on climate change.

President Trump entered the White House with an environmental policy agenda opposed to that of the Obama administration and many other nations that have pledged support to the Paris climate agreement. The Washington Post's Chris Mooney breaks down what a Donald Trump presidency will mean when it comes to climate change. (Daron Taylor/The Washington Post)

Read more:

Trump names Scott Pruitt, Oklahoma attorney general suing EPA on climate change, to head the EPA

Scientists are frantically copying U.S. climate data, fearing it might vanish under Trump

America’s first ‘clean coal’ plant is now operational — and another one is on the way

For more, you can sign up for our weekly newsletter here and follow us on Twitter here.