Scientists say that climate change is one of the most pressing issues of our time. But if you ask policy makers, you might hear them argue that combatting it is just too expensive a battle to fight. President Trump called the Paris climate accord a “self-inflicted major economic wound” when he announced that the US will back out of the agreement. He’s also proposed slashing the Environmental Protection Agency’s budget by 31 percent. Mick Mulvaney, the director of the Office of Management and Budget, said that funding efforts to curb rising global temperatures are “a waste of your money.”

But they are dangerously wrong. In fact, experts say that the economic costs of climate change are so massive that delayed action, or inaction, is the most expensive policy option out there.

OMB Director Mick Mulvaney on climate change: "We consider that to be a waste of your money" https://t.co/JaqaoOPfhZ — Alysha Love (@News_with_Love) March 16, 2017

First, let’s get this out of the way: there is overwhelming evidence that climate change is real, and caused by carbon emissions. Scientifically, the debate’s over and this is our fault — no matter how much Scott Pruitt or Ryan Zinke try to duck responsibility on behalf of humankind.

Sitting out on global warming is a bad deal for America

Second, there are big chunks of the US economy that depend on the global temperature staying put — like the agriculture and fish industries, for example. All told, the agriculture and food sectors account for more than $750 billion dollars of the United States’ gross domestic product, according to an EPA report.

Physicist William Happer loves to say that plants grow better when there are higher atmospheric levels of the greenhouse gas carbon dioxide, but that’s only one part of the picture. Most plants also have specific temperature and moisture ranges. And as global temperatures climb, severe droughts, extreme rain and snowfall, flooding, and heatwaves have already started to increase — making it a lot harder to grow crops no matter how much they love guzzling down that CO2.

Unchecked climate change will hit farmers where it hurts

We’ve started seeing some of the consequences of climate change on agriculture already, according to a government report: high temperatures in 2011 cost meat producers more than $1 billion dollars in what the EPA called “heat-related losses.” Unseasonably warm evenings in 2012 caused Michigan’s cherry crop to bud too early, causing $220 million in damage. California’s record-setting drought, which was exacerbated by global warming, cost the state’s agriculture sector $603 million and 4,700 jobs between 2015 and 2016. Unchecked climate change will hit farmers where it hurts.

Let’s talk coastal property, too, since we know how much time President Trump spends at Mar-a-Lago. Florida’s in big trouble because of the sea level rise, a consequence of the warming planet. By 2050, between $15 billion and $23 billion of property will be underwater in the state. By the end of the 21st century, that could climb to between $53 billion and $208 billion, according to The Risky Business Project’s Climate Risk Assessment. And that’s just in Florida. Nationwide, The Risky Business Project estimates that anywhere from $66 billion to $106 billion of coastal real estate is probably going to hard to enjoy without a snorkel by the year 2050.

This is bad for more than just Mar-a-Lago: massive coastal flooding could also have major ripple effects on the economy, according to a report by government-sponsored mortgage company Freddie Mac. Coastal businesses could relocate or simply go under, taking jobs with them. Lenders and mortgage insurers could also suffer huge losses because, the report says, “It is less likely that borrowers will continue to make mortgage payments if their homes are literally underwater.” It gets worse: “Non-economic losses may be substantial as some communities disappear or unravel. Social unrest may increase in the affected areas.”

“It is less likely that borrowers will continue to make mortgage payments if their homes are literally underwater.”

Big picture: global warming could cause the global economy to plummet — leading to a 23 percent drop in gross domestic product per person by the year 2100, according to a 2015 study published in Nature. “We’re basically throwing away money by not addressing the issue," Marshall Burke, an assistant professor at Stanford University, told Time.

Even bankers agree — and they’re not known for being tree-huggers. A 2015 report published by Citigroup estimates that that climate change could cost the global economy between $2 trillion and $72 trillion between 2015 and 2060. Who else but a group of financial wonks could write something like this: “The cumulative losses to global GDP from climate change impacts (‘Inaction’) from 2015 to 2060 are estimated at $2 trillion to $72 trillion depending on the discount rate and scenario used. Lower discount rates encourage early action.”

Trump, of all people, should see how bad a deal it is

The Department of Defense not only acknowledges climate change, but warns that it could exacerbate “poverty, social tensions, environmental degradation, ineffectual leadership and weak political institutions that threaten stability in a number of countries.” ProPublica recently obtained an unpublished testimony by Secretary of Defense James Mattis, who told the Senate Armed Services Committee, “Climate change can be a driver of instability and the Department of Defense must pay attention to potential adverse impacts generated by this phenomenon.”

One of the most frustrating parts of Mulvaney’s press conference is that he can just lob statements like fighting climate change is a “waste of money” out into the world — and people might believe it. But there are real experts out there, who spend time and money to collect data, analyze it, and publish their results before their conclusions might be somewhat accepted as something resembling fact.

Maybe politicians making claims about science they don’t understand should have to go through the scientific peer-review process — even Reviewer 2 wouldn’t let Mulvaney get away with this kind of wild talk:

We wish to thank Reviewer 2 for their insightful monograph and sincerely apologize for not having written the paper they wish they had. — Shit Academics Say (@AcademicsSay) April 2, 2015

The most painful part? Even the world’s best efforts to combat climate change might not be good enough. But waiting to start fighting global warming — or sitting out the fight altogether — is a bad deal for America’s future. Given President Trump’s claims about his business acumen, he, of all people, should see that.

Why we need the EPA:

Update June 8th 11:00AM ET: This article was originally published on March 16, 2017 and has been updated to include a video, and relevant current events.

Correction: An earlier version of this article stated “from $66 billion to $106 billion of coastal real estate is probably going to hard to enjoy without a snorkel by the year 2100.” The correct date is 2050. We regret the error.