In all of U.S. history, there’s never been a storm like Hurricane Harvey. That fact is increasingly clear, even though the rains are still falling and the water levels in Houston are still rising.
But there’s an uncomfortable point that, so far, everyone is skating around: We knew this would happen, decades ago. We knew this would happen, and we didn’t care. Now is the time to say it as loudly as possible: Harvey is what climate change looks like. More specifically, Harvey is what climate change looks like in a world that has decided, over and over, that it doesn’t want to take climate change seriously.
Houston has been sprawling out into the swamp for decades, largely unplanned and unzoned. Now, all that pavement has transformed the bayous into surging torrents and shunted Harvey’s floodwaters toward homes and businesses. Individually, each of these subdivisions or strip malls might have seemed like a good idea at the time, but in aggregate, they’ve converted the metro area into a flood factory. Houston, as it was before Harvey, will never be the same again.
Harvey is the third 500-year flood to hit the Houston area in the past three years, but Harvey is in a class by itself. By the time the storm leaves the region on Wednesday, an estimated 40 to 60 inches of rain will have fallen on parts of Houston. So much rain has fallen already that the National Weather Service had to add additional colors to its maps to account for the extreme totals.
Harvey is infusing new meaning into meteorologists’ favorite superlatives: There are simply no words to describe what has happened in the past few days. In just the first three days since landfall, Harvey has already doubled Houston’s previous record for the wettest month in city history, set during the previous benchmark flood, Tropical Storm Allison in June 2001. For most of the Houston area, in a stable climate, a rainstorm like Harvey is not expected to happen more than once in a millennium.
In fact, Harvey is likely already the worst rainstorm in U.S. history. An initial analysis by John Nielsen-Gammon, the Texas state climatologist, compared Harvey’s rainfall intensity to the worst storms in the most downpour-prone region of the United States, the Gulf Coast. Harvey ranks at the top of the list, with a total rainwater output equivalent to 3.6 times the flow of the Mississippi River. (And this is likely an underestimate, because there are still two days of rains left.) That much water—20 trillion gallons over five days—is about one-sixth the volume of Lake Erie. According to a preliminary and informal estimate by disaster economist Kevin Simmons of Austin College, Harvey’s economic toll “will likely exceed Katrina”—the most expensive disaster in U.S. history. Harvey is now the benchmark disaster of record in the United States.
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