President Trump's 2018 budget proposal also represents a major departure from recent years. The blueprint slices more than $10 billion off the current State Department budget, including zeroing out U.S. commitments to the international climate process and funding. That's in addition to cuts into clean energy innovation and domestic climate programs (though the final budget passed through Congress will likely look different).
In a letter to State Department staff, Tillerson endorsed shrinking the budget.
"It acknowledges that US engagement must be more efficient, that our aid be more effective, and that advocating the national interests of our country always be our primary mission," Tillerson wrote, according to the Washington Post. "Additionally, the budget is an acknowledgment that development needs are a global challenge to be met not just by contributions from the United States, but through greater partnership with and contributions from our allies and others."
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What happens to the Paris Agreement itself will be perhaps the strongest signal of how the US approaches climate change on the international stage. Reports indicate that presidential advisor Steve Bannon and the more populist faction of Trump's inner circle want the U.S. to exit the agreement, which Trump said he would "cancel" during the campaign.
Another faction of the White House is in favor of staying in the Paris Agreement, of which Tillerson is likely a part. During his testimony before the Senate Foreign Relations Committee, he said, "I think we're better served by being at that table than leaving that table," though he also puts the brakes on a bit by noting "as we commit to those accords, are there any elements of that that put America to a disadvantage?"
Any changes to how the U.S. acts - or doesn't act - on climate change come at a crucial time for the world. The planet just endured its third straight year of record-setting heat, and 16 of the 17 hottest years have all occurred since 2000.
While renewable energy investments are at an all-time high, there's still a vast amount of work the world will need to do to shift away from fossil fuels and avoid the worst impacts of climate change. What role the U.S. plays in that remains to be seen.
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