Does Global Warming Make Hurricanes Worse?

With a particularly bad hurricane season in 2017, there's been a lot of talk about climate change and hurricanes, and it's been a bit difficult to find actual science in the conversations. I figured I'd post what good information I've been able to find on the topic to answer some questions.

Does global warming make flooding from storm surges worse? Yes...

We know that sea levels are rising. For a given storm surge then, it is obvious that it will flood more areas. Areas close to sea level are more affected by storm surges, and sea level rise means more stuff gets closer to sea level. 

This article has a great analysis of how this will progress in the next few decades. There's another one here that was really popular following Hurricane Sandy. There is enough evidence that this is happening to assume it is true.

Does global warming increase the potential rain amounts from hurricanes? Yes...

There is no question that warmer air can hold more water and this is described by the Clausius–Clapeyron relation. The water-holding capacity of air increases by ~7% for each 1 degree Celsius rise in temperature. We have a number of studies that found that global warming has already increased the frequency of extreme rainfall events (example 1 and example 2). We also have good reason to believe that they will continue to get worse (example 1 and example 2...start at page 7 on example 2).

Several recent storms have resulted in extreme precipitation, including Tropical Storm Allison and Hurricane Harvey that both devastated the Houston area (I'm in Austin, TX so those are well-known here...I know there are terrible ones in other places also). There's enough evidence now to assume that this will get worse for a given storm.

Does global warming increase hurricane wind speeds? Probably...

I couldn't find as much research here, but the research available is consistent. There is one study that found that intense storms are getting more intense. There's also this cool plot that I've posted previously that implies that warmer waters can lead to more intense storms:

Global warming makes waters warmer on average, and warmer waters can fuel more intense hurricanes, so it's reasonable to conclude that global warming can lead to more intense hurricanes.

The primary question here is if increased wind shear from global warming will counter this effect. The available studies (example 1 and example 2) don't point to a consistent answer yet, so I wouldn't be 100% confident in this, hence the 'probably' instead of 'yes'.

Will more hurricanes make landfall in the US because of global warming? Unclear...

I haven't found much consistent information on this. You'd expect more hurricanes because of warmer oceans, and you'd expect fewer because of increased shear from the warming. So few hurricanes make landfall that it's also very difficult to infer much from the stats. One study projects more strong storms and fewer overall storms, but that's about it. Since I can't find anything really conclusive, I'm calling this unclear.

Will hurricanes occur further north going forward because of global warming? Unclear but more likely than not...

There's surprisingly very little out there that I could find on this. There is a study that found that the tropics appear to be expanding because of global warming. The study listed in the previous question finds intense storms occurring more frequently at high latitudes in a warmer world than the present one. Another study projects more hurricanes hitting Europe. There's still not enough available for me to consider this settled though so I'm calling it unclear but noting that the little bit of information available suggests that it's probable.

Will hurricanes move more slowly and get stuck over areas because of global warming? Unclear...

One thing that made Hurricane Harvey particularly devastating is the fact that it stayed in one location for an extended period and rained in the same places for days. Will this become more common? I could only find one study remotely related to this, and it's not enough to call this anything other than unclear.

No comments:

Post a Comment