Meteorologists seem to be running out of adjectives to describe the devastation of Harvey, with phrases such as "beyond anything experienced" and "1-in-1,000 year event" being thrown around. But why is Harvey so bad? The New York Times explains that it involves an unusual combination of factors, the main ones being unusually warm water in the Gulf of Mexico and weak winds in the upper atmosphere that have allowed the storm to essentially park in place. On top of that, Galveston Bay is elevated because of the storm surge, which means the copious amount of rain falling on Houston isn't draining. "A 2- or 3-foot storm surge alone would not have been catastrophic," a storm surge expert tells the newspaper. "It was all these ingredients coming together."
So how about the boogeyman of climate change? As the Atlantic explains, trying to show any such link is a tricky affair. But in a general sense, climate change makes ocean temperatures higher, which might have played a role in a unique Harvey phenomenon. Most hurricanes weaken as they approach land and churn up deeper, colder water. But Harvey actually intensified, in part because even the deeper water it was churning up was unusually warm. "This is the main fuel for the storm," says Kevin Trenberth of US National Center for Atmospheric Research. "Although these storms occur naturally, the storm is apt to be more intense, maybe a bit bigger, longer-lasting, and with much heavier rainfalls [because of that ocean heat]."