Last month was the hottest month is recorded history.

Catastrophic climate change is already costing tens of billions in damage, displacing more and more people, causing more and more casualties from California fires to the increasing force of hurricanes, the spread of desert and drought.

It is real, accelerating and poses what literally is an existential threat.

And the commander-in-chief of the most powerful nation in the world remains in denial.

President Donald Trump not only denies the threat posed by manmade climate change, he consciously, purposefully and perversely works to accelerate it.

This week, the administration announced that it would roll back regulations to limit methane emissions from natural gas sites on public lands. Methane is a potent gas, more destructive than carbon dioxide in trapping the earth’s heat, according to the United States Environmental Protection Agency.

It now represents about 10 percent of U.S. greenhouse gas emissions — but the administration is intent on making that worse.

Trump’s rationale is consistent. He hates all things Obama, particularly in the area of the environment, so he’s made reversing Obama’s achievements — leaving the Paris Climate Accord, rolling back auto mileage standards, and weakening greenhouse gas controls — a first priority.

He is ideologically committed to deregulation, claiming that it will unleash growth and blind to the damage caused to clean water, air, much less to the threat to our existence.

The methane regulation, the Department of Interior announced, was “unnecessarily burdensome” to the multibillion dollar natural gas industry.

The easing of methane rules, Trump’s EPA estimates, will save the oil and gas industry $17 million to $19 million a year. It will cost far more than that in contributing to the acceleration of global warming.

Ironically, the big oil and gas companies oppose the deregulation. They are trying to sell natural gas as the environmentally friendly transition fuel from coal, in an era when they understand global warming will make the transition inevitable.

Methane leaks foul their story.

Trump will make it harder for them to sell themselves in the future.

The United States has been taken by surprise by enemies in the past — think Pearl Harbor or 9/11. We’ve had our share of incompetent generals and foolish leaders — think of the north’s Civil War generals before Ulysses S. Grant or the folly of the Iraq debacle.

But we’ve never had a president committed to making a clear and present danger to our security worse. We’ve never had one so divorced from the reality he faces.

Trump argues that his deregulation is unleashing growth and prosperity. But his economy has grown no faster than that of Obama, who was moving the country to meet the challenge of climate change.

The scientific consensus is that we have about 10 years to move dramatically to limit greenhouse gases and transition to renewable energy. Even now, we face accelerating natural disasters triggered or worsened by global warming.

Trump wants us to ignore the human and financial costs of this present threat and celebrate deregulation that will save the natural gas companies what to them is chump change. Never in our history has our national security been so threatened by the very president charged with defending it.

The Democratic majority in the House will move to block this ruling; state attorney generals have already announced that they will sue to reverse it. But Republicans in the Senate under Mitch McConnell will block congressional action. And the legions of judges that Trump has appointed are likely to limit judicial remedy.

The perversity will continue until Americans in large numbers — spurred by a younger generation that understands that their future is at risk — rise up and demand action and sweep out those standing in the way.

That is already long overdue.