If things don’t change soon, we’re toast.

We saw it last week when Hurricane Michael wiped out entire communities in Florida, and last month when Florence wreaked havoc in the Carolinas. We’ve seen it on Long Island, where we will face even worse flooding than the destruction from superstorm Sandy.

The Earth is getting hotter, and more intense storms are only one result. If we don’t stop the warming, the changes will be irreversible. Hundreds of millions of people are at risk, with damages in the trillions of dollars. Among the problems: severe coastline flooding, more intense droughts and worsening wildfires; declining fish catches and crop yields; mass migrations of people, especially from the tropics; and the collapse of ice sheets in Antarctica and Greenland, accelerating sea level rise.

That scenario was described in detail by the UN’s panel on climate change, in a report it dropped as Michael was forming. The panel, the world’s definitive source on climate science, is by nature conservative. Its 91 scientists from 40 countries analyzed more than 6,000 studies.

In the Paris pact of 2015, countries pledged to reduce greenhouse gases enough to limit the rise in temperature above preindustrial levels to 3.6 degrees Fahrenheit. The panel analyzed a lower threshold of 2.7 degrees, and found that beyond that number, dire changes start to cascade. Given the current lack of progress, the UN says we’ll see those changes by 2040, way earlier than previously forecast. Put the urgency in perspective: An infant born today will graduate college around then.

The panel was direct in its prescription: Transform the world’s energy system, period. Nothing else will work. That means a 40 to 50 percent reduction in emissions by 2030, and a carbon-neutral world by 2050. It means more solar and wind energy. It means an aggressive push toward electric cars. It means a tax on carbon emissions. It means planting more trees, and inventing ways to remove greenhouse gases from the air. And it means the virtual elimination of burning coal — the easiest way to get carbon dioxide out of the atmosphere is to never put it there.

This calls for leadership that grasps the threat and has the courage to take tough steps. But President Donald Trump is steering us toward a climate disaster. His administration has moved to weaken limits on power plant emissions and roll back fuel efficiency standards. He plans to remove the United States from the Paris agreement. And he wants to burn more of what he calls “clean, beautiful coal.”

This recklessness isn’t like Nero fiddling as Rome burns. This is Nero pumping gasoline onto the flames.

Trump expressed skepticism about the report while saying he would look at it. But his representatives had to approve the panel’s conclusions, and did. His Pentagon says climate change is a national security issue. His National Highway Traffic Safety Administration projects a 7-degree rise in global temperatures by 2100. Even Exxon Mobil Corp. has announced its support for a carbon tax.

Trump isn’t alone in his dereliction. Big emitters like China and India aren’t doing their share. But we need to lead. We won’t be insulated from the changes. But we can help stave them off. The UN report is a warning. Monster storms are the alarm: The window is short. The potential for destruction is huge. We must act. Now.