Was Hurricane Irma Caused By Global Warming?

Hurricane Irma is the most powerful storm ever recorded over the Atlantic, devastating the Caribbean and Florida last week and this past weekend, with many citing climate change as a cause. The science is complex, yet as it happens, hurricanes aren't caused by global warming directly, but climate change does make their effects much more disastrous. 

Looking at models for future climate change, the good news is that by the end of the 21st century, there will actually likely be fewer hurricanes per year. But the bad news is that those hurricanes will be a lot more powerful - by 2% to 11%, depending on which model you use and potentially more destructive, according to the The Geophysical Fluid Dynamics Laboratory (GFDL). Here's why.

Firstly, hurricanes will bring more rainfall. Warm air can hold more water, and water vapour is predicted to increase by 7% for every degree centigrade of warming so when hurricanes hit, they bring much more rain, meaning more flooding.

Secondly, climate change means sea levels are rising. That results in storm surges reaching further inland than they once did again leading to more flooding.

Thirdly, sea waters will continue to get warmer. This is important for hurricanes in particular as they are fuelled by warm air rising from the sea. Higher water temperatures mean warmer air - which means bigger, more powerful hurricanes.

That partly explains why Irma was so devastating, the Atlantic Ocean's waters have been unusually warm. This chart, from last week, shows them 0.5°C to 1.25°C above average.

  Source: GFDL

Source: GFDL

So while there will be fewer storms, they will be more powerful, and the worst is likely to come. The GDFL projects a 30% increase in total damage from Atlantic hurricanes by the year 2100. 

If we want to reverse the effects of climate change, we have to act fast. Here are a few things you can do:
-Change light bulbs to compact fluorescents or LEDs.

-Unplug computers, TVs and other electronics when not in use.

-Wash clothes in cold or warm (not hot) water.

-Dryers are energy hogs, so hang dry when you can.

-Buy organic and locally grown foods.

-Let store managers and manufacturers know you want products with minimal or recyclable packaging.