Donald Trump locked up his status as the presumptive Republican presidential nominee this week and environmentalists declared war on him moments later.

Trump is one of the most prominent climate change doubters in modern politics, often musing on Twitter that cold spells or heavy snowstorms are proof that global warming is not real. He once theorized that climate change is a conspiracy created by the Chinese, though he later claimed to be joking.

During his victory remarks on Tuesday and again on Thursday at a campaign stop in West Virginia, Trump promised to get coal miners back to work and increase coal production in Appalachia. His campaign promises include eliminating the Environmental Protection Agency.

Given that track record, it's no surprise that in the following days environmentalists declared they'll do whatever it takes to stop The Donald from taking the White House.

The Sierra Club was among the first groups to put its members on notice that they would be going all out to stop Trump.

"Donald Trump has made clear that he has a total disregard for the crisis posed by climate change, as well as virtually all other essential environmental and public health protections, and those are just a few reasons we will be speaking out, organizing, and doing everything we can to stop Trump this election," said Khalid Pitts, political director at the Sierra Club. "There is too much on the line to not take action."

The next president will have a major role in deciding how the United States, and by extension the entire world, fights off the effects of climate change. The Paris Agreement, signed by the U.S. last month after being agreed to in December, is not a legally-binding treaty so it's feasible that the next president could simply decide to ignore its provisions.

Many of the regulations that would keep the United States on target to meet its carbon emissions cuts set out in the Paris Agreement were unilaterally implemented by President Obama and his administration. A President Trump could repeal those regulations as soon as he took office if he wanted.

Pitts said the Sierra Club and its members would do whatever it takes in the coming month to make sure that doesn't happen.

"The Pope, the Dalai Lama, big business leaders, huge majorities of the American public and nearly every nation on earth want action to tackle the climate crisis, but Trump's refusal to acknowledge reality would completely undermine U.S. global leadership and our key alliances around the world," he said.

The League of Conservation Voters similarly released a fact sheet called "President Trump: An Environmental Disaster" after Trump's Indiana win.

The green group pointed out a myriad of ways that Trump differs from their agenda, including his refusal to comment on the lead water crisis in Flint, Mich., and his statement that he would have skipped the Paris climate conference that resulted in the first-ever worldwide climate change agreement.

The League of Conservation Voters has already endorsed former Secretary of State Hillary Clinton for president and plans to step up its attacks on Trump as the general election fight heats up.

"Donald Trump lacks the judgment, character and temperament to handle the coming challenges," the group said in a statement. "A Donald Trump presidency would be an environmental disaster."