Climate activists protested Rex Tillerson’s nomination in T. Rex costumes

With a name like Rex, such a stunt was inevitable.

On Wednesday, environmental activists marched around Washington, D.C., in Tyrannosaurus rex suits to show their disdain for Rex Tillerson, the former CEO of ExxonMobil and Donald Trump's nominee for secretary of state.

The protest coincides with Tillerson's confirmation hearing held by the Senate Foreign Relations Committee.

"We won’t allow our climate diplomacy to be in the hands of a dinosaur like Rex Tillerson," May Boeve, executive director of 350.org, the grassroots environmental group leading Wednesday's march, said in a statement. "By tapping Rex Tillerson as Secretary of State, Donald Trump is essentially declaring war on our planet and betting against a livable future."

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Climate advocates argue that tapping the long-time leader of a major fossil fuel company to be the nation's top diplomat would undermine U.S. efforts to drive global reductions of greenhouse gases and curb the world's use of oil, coal and natural gas.

Tillerson's critics also abhor the idea of appointing the former CEO of a company that's been accused of deliberately misleading investors and the public about the connections between climate change and burning fossil fuels.

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Exxon is currently under investigation by the attorneys general of Massachusetts, New York and the U.S. Virgin Islands for researching climate change in the 1970s and then spending millions of dollars to spread misinformation through think tanks and friendly politicians.

The movement surrounding the activism and investigations is known by the hashtag #ExxonKnew.

Tillerson joined Exxon Company USA in 1975 as a production engineer and spent the next 41 years climbing up Exxon's corporate ladder. Following his nomination as secretary of state, he retired from his positions as CEO and chairman three months earlier than planned, on Dec. 31, 2016.

The company has denied climate advocates' accusations. Exxon has said that it accepts the mainstream scientific consensus that humans are causing global warming, and that "the risk warrants action," according to Exxon's website.

Sierra Club, another environmental group involved in Wednesday's demonstrations, said Tillerson's long track record in the oil and gas business should should tarnish his reputation, not bolster it.

"At a time when the climate crisis is deepening, both the United States and the world deserve much better than having a fossil fuel tycoon run U.S. foreign policy," Michael Brune, Sierra Club's executive director, said in a statement.