Hurricane Harvey pummeled southern Texas all weekend, causing apocalyptic flooding. Worse, several more days of torrential rainfall are in the cards, as Harvey is predicted to slowly wander slightly back out to sea and then make landfall again in a day or two. Several deaths have already been confirmed, and forecasters estimate there will be up to 50 inches of rain in the worst-hit areas.

This destruction is a window into the future of climate change. This is what happens when humanity fails to either meaningfully restrict greenhouse gas emissions or prepare for the damage that is certainly coming.

Now, before the inevitable pedant brigade pounces in, that doesn't mean Harvey was definitely caused by climate change. Global temperatures have only markedly increased for a few decades, and extreme weather events are rare and random by definition. It will take many more years for enough data to be collected to be able to establish causality.

But what we can say is that climate science predicts with high confidence that increased temperatures will increase the likelihood of extreme weather.

It will make hurricanes that do form stronger. It may also increase the number of hurricanes, though that's harder to predict with certainty. It's also besides the point. A storm doesn't need to qualify as a hurricane to pose many of the same dangers. Simple big storms can still have high winds, tornadoes, and especially flooding, which is the major danger along the Gulf Coast.

And when it comes to attributing an increased flooding trend directly to climate change, we are on firmer ground (so to speak). As the 2014 Intergovernmental Panel on Climate Change report notes, models predict that increasing temperature ought to cause greater precipitation extremes in both directions — both drought and flooding, though there are likely more areas of heavy precipitation. As climate scientist Michael Mann writes, "Harvey was almost certainly more intense than it would have been in the absence of human-caused warming."

All that is seriously worsened by abysmal American preparedness — particularly in the South, where drainage and other flood protection infrastructure is often designed poorly and maintained worse. Southern Texas is notorious in this respect — not as bad as New Orleans, which still has not been completely rebuilt from Hurricane Katrina — but still bad. As this ProPublica/Texas Tribune report details, Houston has been increasing its vulnerability to flooding, mainly through ever-sprawling development. Prairie absorbs water to some extent, while concrete and pavement sheds it quickly. Paving over soil therefore increases the speed and volume of runoff, and hence flooding. (Naturally, the Republican head of the local flood control district denies this is happening and has no plans to study how climate change might affect the local region.)

Furthermore, the Houston area also has some critical infrastructure that is seriously vulnerable to a direct hit from a major hurricane — like the Johnson Space Center and the Houston Ship Channel, which has the largest oil refinery complex in the entire country. At the time of writing, the Johnson center is closed but operational, while refineries with about one million barrels of daily capacity have been shut down — with more to come, most likely.

Houston has been hit with a 100-year flood — a rainstorm that, going by previous records, has a 1 percent chance of happening in one year — in 2015 and in 2016. Now in 2017 it's enduring what will probably be the worst flood in the city's history. (That, plus the suggestive science on climate change precipitation, would suggest the probabilities need to be updated.)

And that brings me to President Trump. It's not clear how the disaster response is going, though I would certainly not expect top-notch performance. But just days before Harvey hit, Trump announced that he was going to rescind an Obama executive order that would require buildings receiving federal funding to consider climate change and build above extreme flood levels. Since there is a big federal program to provide flood insurance to many such buildings (that is incidentally nearly bankrupt due to massive claims of late), this amounts to a government subsidy to build in flood-prone areas.

That's Trump alright: stupendous, almost unimaginable idiocy in every situation. But here it drives home the fact that failing to act on climate change is putting the United States under direct threat of physical devastation. If ISIS had some plot to blow up the nation's biggest oil refinery, it would be instant justification for limitless spending and endless war. But because the threat comes through abstract and slow-moving scientific processes — and because one of our two political parties has become intellectually unhinged — we sit here, twiddling our thumbs, until the disaster is on us.

Well, it's here now — and the longer we wait, the more expensive and deadly prevention and defense will be. It's time to get moving.