Climate activists pointed to the historic rainfall and epic flooding as exactly the type of extreme event forecast to occur as the globe warms. Skeptics cited a long list of tropical storms that slammed Texas even before the buildup of greenhouse gases in the atmosphere.
So who’s right?
In some ways, the question is premature, even unseemly, while search and rescue efforts continue. And a definitive answer won’t come until scientists conduct post-storm “attribution” studies. In all likelihood, though, the conclusion will be that climate change didn’t cause Harvey, but it almost surely made the storm worse.
Harvey produced 40- to 50-inch rainfall totals that left parts of Houston looking like Venice and rivaled snowfall accumulations from blizzards in the Northeast. It was, in fact, the most extreme rainfall event on the continental United States in recorded history.
Such events are consistent with the basic science of climate change: Warmer than normal water temperatures, in places such as the Gulf of Mexico, provide heat energy that fuels the formation and rapid strengthening of tropical storms. Warmer air holds more water vapor, which in turn produces more rainfall. And rising sea levels exacerbate storm surge and inland flooding.
According to the National Climate Assessment, “Heavy downpours are increasing nationally (in recent decades), with the largest increases in the Midwest and Northeast. Increases in extreme precipitation are projected for all U.S. regions.”
This isn’t just happening in North America.
Even as Harvey riveted the nation’s attention this week, the death toll topped 1,000 from unusually severe monsoonal rains half a world away in Bangladesh, India and Nepal.
In the coming days and weeks, expect to hear politicians describe Harvey as an “act of God” that had little or nothing to do with human-induced climate change. Even if climate change is real, they’ll add, a serious effort to curb greenhouse gas emissions, through a carbon tax or other means, would be too expensive.
On Wednesday, the private company AccuWeather estimated that Harvey could end up costing $190 billion, making it the priciest natural disaster in U.S. history, equal to the combined cost of Hurricanes Katrina and Sandy.
With that kind of price tag atop a torrent of human misery, the question isn’t whether the nation can afford to get serious about global warming. We can’t afford not to.
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