It’s impossible to say that climate change is responsible for any individual storm or hurricane, but climate change is making these storms stronger.
How much stronger?
It turns out, Hurricane Harvey is the ideal test case to measure how a warming planet and warming oceans, amplify our worst storms.
[OPEN] In August of 2017, Hurricane Harvey dumped 27 trillion gallons of rain over four days in and around eastern Texas.
Some places got more than four feet of rain, that's a kindergartener's worth.
2017 was a particularly nasty Atlantic hurricane season.
There were 6 major hurricanes that impacted hundreds of thousands of people, costing billions of dollars and thousands of lives.
In future hurricane seasons, storms will likely be stronger and carry more rain.
The math here’s pretty simple.
The world’s oceans have absorbed more than 90% of the excess heat trapped by our emissions.
And every bit of extra heat the ocean absorbs is fuel a hurricane can burn to crank up its wind speeds.
The amount of precipitation a hurricane can hold depends on how much heat it pulls from the ocean’s surface.
So hotter oceans also lead to wetter hurricanes.
We can see this really well with Hurricane Harvey.
Leading up to Harvey, the Gulf of Mexico and oceans around the world were at record highs of “ocean heat content,” a fancy name for how much thermal energy the water holds.
The Gulf was primed to feed a superstorm.
Isolated in the Gulf of Mexico, Harvey’s path allowed researchers to tease out the precise relationship between extra ocean heat and extra rain.
Before Harvey, surface water in the Gulf was hot - more than 30ºC/86ºF, after, the waters had given up more than 2ºC.
All that heat had been sucked up into the storm in the form of stronger winds and heavier rains.
This data tells us the warmer Gulf of Mexico likely turbo-charged Harvey from a bad storm into a historic superstorm.
Putting an exact number on that is difficult, but estimates suggest climate change increased Harvey’s precipitation over land by up to 40% As much as 10.8 trillion extra gallons of rain, courtesy of climate change.
If warming trends continue, the trend of slower, stronger, and wetter storms will continue too.
But the evolution and aftermath of Harvey shows us that climate change is already making storms stronger and more costly, and that’s something we have to think about today.
In any given year, it’s impossible to predict who and where will be hit by a hurricane.
But consider that 40% of the world’s population lives within 100km/62 miles of the ocean.
To deal with tomorrow’s climate-charged hurricanes we’re going to need serious mitigation and adaptation efforts: better building codes, more flood protection, and effective emergency evacuation plans, to make sure those places are still here after the storm passes.