Are Hurricanes Getting Worse?

This year, much like wildfires, hurricanes have been dominating the headlines. Many stories will report on the impacts, devastation, and costs of rebuilding.  They might even call up memories of hurricanes past, comparing the damage, size, and characteristics.  But we don’t see enough of the connection between hurricanes and human behavior.  How are we actually creating this self-destruction?

hurricanes and climate change

I’m of course referring to climate change, and our propensity for ignoring scientific data that tells us man-made activities are contributing to a warming planet.

You may know that climate change has been considered the culprit of hurricanes. But you might not know how. 

Firstly, hurricanes are not a consequence of climate change alone.  Hurricanes are a natural function of a stable climate.  That’s why it is hard to pinpoint which storms, or level of intensity, can be attributed to climate change.

What we do know is that climate change increases the severity of storms.  A warming planet leads to:

  • Stronger storms (wind speed)
  • Wetter storms (more water at a time)
  • More frequent storms
dark storm with lighting streaks over water and small town

the heat of the storm

When I was a kid, I used to fear and love the thunderstorms that would come through on a breathless, steamy, summer afternoon.  The heat would circulate around you all day.  You could hear it in the insect buzz, a rising, high-pitched plea for a drop in temperature. 

I didn’t have air conditioning.  I was outside most of my summers, so became familiar with the stickiness of childhood play, and the cooling rush of water from a small creek bed on my dirty bare feet.  When those thunderstorm clouds would rise, and the day would give in to the dark, it was like the world standing still.  Waiting for that first crack of thunder.  Praying for the rain. The greens of the trees stood out so bright then, against those grey skies. And the stillness warned you of the power that lay in those cloudbanks.

Like the heat couldn’t rise any longer; it had reached it’s tipping point, and all the moisture that rose in that steamy air had accumulated enough and was about to spill back onto earth with the fury of an angry sky.

windy, rainy day at the beach with buildings in the fog

warming and storming

And that’s actually exactly how that works.

Hot air holds more moisture than cold air.  The warmer the air, the more potential it has for holding water.

There’s a well understood equation for this, called the Clausius Clapeyron.  This equation shows that the atmosphere’s potential for holding moisture increases by 7% for every 1˚C of warming.

NASA image eye of a hurricane

are hurricanes getting more frequent?

And since Industrial Revolution, the global average temperature has risen 1˚C.  We’ve seen an increase in storm frequency and intensity over the recent years that scientists are attributing to man-made global warming. From 1966-2009, the Atlantic Basin experienced an average of 11 storms annually, with 6 hurricanes.  From 2000-2014, however, storms increased to 15 per year, with an average of 7 hurricanes.  The National Hurricane Center has a fantastic chart for this. 

However, there is debate as to how warmer weather will impact frequency.  One thought is that frequency will increase, as well as intensity.  Another is that fewer storms may form, but the ones that do form will be more intense.

storm over the ocean with heavy rainfall

are hurricanes getting more intense?

And speaking of intensity, has there been an increase recently?  The data says yes.  In the last 30 years, storms of Category 4&5 caliber have nearly doubled, from 10 to 18 globally, according to the National Science Foundation.  It’s generally accepted that intensity will undoubtedly rise as global temperature does.

And our global temperature will rise.  We are continually contributing man-made emissions of greenhouse gases that will warm the planet for years to come.  By 2036, it is expected that we will have contributed to 2 degrees of warming. 

That might not seem like a lot- 2 degrees.  But to put it into perspective, the last ice age was due to just 2 degrees less than average global temperatures.  This was caused by reductions in CO2 as well as sea surface temperatures.  Both of which are increasing now.  Judging by our past, there’s huge global climate impacts from small variants in average temperature.

infographic on hurricanes and climate change showing hurricanes getting worse.

business as usual

As we continue with ‘business as usual’, burning fossil fuels and contributing to global greenhouse gas emissions, we will continue to see a rise in global temperatures.  As temperatures rise, sea surface temperatures rise as well, characterizing the perfect combination for storms.  Warmer air holds more moisture, and as these systems travel, they pick up more energy from the warm surface of the water.  As ocean waters warm, we’re likely to experience destructive storms, with more rain, flooding, storm surge, and high winds. 

For more information on hurricanes, check out this How Stuff Works article.  Lots of good information there!

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