Hurricane Harvey, now Tropical Storm Harvey, has brought devastation to Texas and parts of Louisiana. Although it doesn’t compare to the monsoon-driven floods that are ravaging South Asia at the moment, it’s safe to say that it’ll be one of, if not the most costly natural disaster in US history. The Federal Emergency Management Agency (FEMA) have said that they’ll be around for “years” to come.
Inevitably, climate change has been brought up – and right now, depending on where you look, the man-made phenomenon has either definitely caused Hurricane Harvey or it has nothing to do with it. As it so happens, there are a few things you can definitely say about climate change in this sense, and a few things you certainly cannot say.
So let’s start with what we definitely cannot say: namely, that climate change caused this natural disaster to occur, because it didn’t. No one can say with any confidence that this exact cause-and-effect relationship can be found here, and no climatologist worth their salt would ever do so.
Hurricanes have been happening ever since Earth has had significant amounts of water. Although the process is still not completely understood, they form when specific types of wind currents coalesce around spots of warm oceanic water located close to the equator.
Hurricanes like Harvey gather strength over warm water, and they lose strength when they drift over cool, dry land. There’s more to it than that, but those are the basics. If humanity hadn’t been changing the climate, hurricanes would still be taking place today.
We also cannot say whether or not hurricanes would be more frequent as a result of climate change. Instinctively, it feels like that this should be the case. After all, all that carbon dioxide we’re pumping into the atmosphere is directly linked to warmer oceanic surface waters, the primary “fuel” source of hurricanes – so you might expect that warmer waters would lead to more hurricanes.
There’s no solid evidence in the scientific community that this is what we’re seeing. Plenty of multidisciplinary studies looking into this link have come up empty handed. More specifically, there’s not enough evidence yet to come down on either side.