Is Climate Change Really Causing Destructive Hurricanes?

As a child, I remember learning about the Greek goddess Cassandra who was blessed with the gift of prophecy, but she was also cursed because no one would believe her predictions. Musing about disasters foretold (but ignored) crept into my head recently as I surveyed some recent opinion pieces on the devastating impact that Hurricanes like Harvey, Irma, Jose and Maria have had.

Some people view these storms as entirely natural phenomena that have little relationship to human activities. Others view these events as a portent of the kind of cataclysmic weather activities, which are an inevitable consequence of human beings burning too much fossil fuels. While still others view these extreme weather incidents in supernatural terms — as a form of divine retribution visited upon a people who have lost sight of God’s ways.

Irrespective of their beliefs and backgrounds, the way people respond to natural disasters can often reveal amazing reservoirs of innate decency, which calls attention to our shared humanity. Unfortunately, when it comes to explaining the causes and significance of such weather events, we remain as divided as ever.

For instance, when climate scientist Kerry Emanuel recently suggested (in an Op-Ed) that we stop calling events like Irma and Harvey “natural disasters” because they have a man-made dimension (in so far as humans are overbuilding in vulnerable areas) he was immediately slammed on semantic grounds alone as the following tweets illustrate:

What’s behind the destructiveness of recent hurricanes?

In the current environment, asking a simple question — like, is climate change causing destructive hurricanes? — seems destined to elicit blowback and controversy. Most scientists insist that global warming is real, that it is caused by human activity (burning too much fossil fuels), and that climate change will ultimately contribute to extreme weather events.

However, there is a class of politicians and business interests who maintain that climate change is a hoax perpetrated by academic elites who want to regulate and micromanage the economy (because they are supposedly unable to create wealth themselves). Ideologies like this are hard to argue with because belief systems usually have an article of faith to explain away each and every fact.

But facts are stubborn, and here are a few that are hard to dismiss:

  • Already, 2017 has been one of the most active and destructive hurricane seasons ever (2005 was the most active and destructive).
  • CO2 emissions (the greenhouse gas emissions that cause heat to get trapped in the atmosphere) are the highest they’ve been in more than a 100 million years.
  • 12.2 percent of the United States is currently impacted by “exceptional drought.”
  • Melting glaciers have led to sea levels that have been rising on average 3.4 millimeters per year. This doesn’t sound like a lot, but higher oceans mean that coastal regions are more vulnerable to flooding and storm surges.
  • 2016 was the hottest year ever recorded and 2017 is shaping up as the third warmest. The last four years in a row have been the most scorching ever.
  • A clear warming trend has been in evidence since the 1880s but has accelerated dramatically in the last two decades. There is an overwhelming consensus among scientists that the planet is heating up and that human activity is responsible for this development. Climatologists have linked higher temperatures to typhoons, wildfires, hurricanes and droughts.
  • Polar ice caps have been shrinking dramatically. These colossal ice sheets help keep the oceans cool by reflecting sunlight. When they melt, ocean levels rise and temperatures increase.
  • Sea temperatures have been rising. Climate scientists have been predicting for years that warmer waters will feed the rapid intensification of hurricanes, a rare phenomena where tropical storms gather steam by drawing on hotter ocean water for fuel.

Rapid intensification of tropical storms

Rapid intensification is supposed to be highly unusual, but this year alone four storms — Harvey, Irma, Jose and Maria — have undergone this process. For a good explanation of how warmer oceans lead to the rapid intensification of hurricanes, check out this video by Dr. Mark DeMaria, Technology & Science Branch Chief at the National Hurricane Center.

Hurricane Harvey, of course, decimated the epicenter of the fossil fuel industry. That irony, needless to say, is not lost on environmental activists, who have been warning about the links between carbon fuels and extreme weather events for decades.

However, most scientists take a cautious approach — refusing to link any one storm (or particularly bad hurricane season) to climate change. As Katharine Hayhoe, an atmospheric scientist at Texas Tech explains, “Climate science is all about the long-term statistics [but] we can say, absolutely without a doubt, that this hurricane [Harvey] took place over altered background conditions. Our planet is very different today than it would have been 50 or 100 years ago.”

The altered background conditions Hayhoe refers to include:

  • Increased water vapor in the atmosphere caused by the greenhouse effect. Hayhoe explains this when she tweeted:

  • Heightened sea levels, which cause more massive storm surges.
  • And warmer oceans, which provide the energy tropical storms need to rapidly intensify so that they become Category 4 and Category 5 storms.

As Hayhoe mentioned, science deals in statistics. If you flipped a coin a dozen times, you would have little basis to conclude if that coin was fair or not. After all, a particular run of heads (or tails) could just be a fluke. However, more observations will lend credence to any theory you have about the coin being fair or not. The same holds true for the theory that more intense weather events are being spawned by climate change.

Connecting the dots on climate change

Fifty years from now, future generations are likely to look back and wonder why so many policymakers (and so much of the public) took so long to connect the dots. Part of the answer lies in human nature.

  • Many people have an emotional or financial stake in the fossil fuel industry, which makes them unwilling to embrace cleaner alternative energy sources.
  • People tend to discount future threats when contrasted with short-term considerations.
  • People seize upon uncertainty to avoid hard decisions (For example, why change my dietary habits when scientists can’t unequivocally prove that potato chips are linked to cancer?)

You can’t link one giant Slurpee soda to diabetes. But a pattern of consuming jumbo-size sugar-laden beverages will increase most people’s risk for developing a metabolic disease like diabetes. Similarly, no one extreme weather event is proof that climate change is the direct cause. But virtually all climate scientists agree that a very real pattern is unfolding.

As you might expect, experts still disagree about the extent to which climate change is exacerbating extreme weather, but experts like Kevin Trenberth, of the U.S. National Center for Atmospheric Research, conjecture that when it comes to hurricanes like Harvey, “The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm. It may have been a strong storm, and it may have caused a lot of problems anyway — but [human-caused climate change] amplifies the damage considerably.”

Extreme weather events like Harvey are a reminder that that human development is a factor when it comes to destructiveness too. Put simply, building in floodplains and coastal regions facing rising seas is neither sustainable nor wise.

As Dr. John Jacob of Texas A&M noted, “Disasters as Hurricane Harvey remind us [that] we should focus on ‘resilient growth’ so we can bounce back from adversity. We want to get these communities affected by flooding to the point where a flood can be seen as an inconvenience and not a disaster.” Presumably, that means paying more attention to climate scientists and experts on watershed and coastal development, who have been warning about the perils of global warming for years.

Will we heed the warning signs? 

It’s too early to tell if the rather unprecedented fury of Harvey, Irma, Jose and Maria will be a wake-up call or if the warning signs will go largely unheeded. Many modern-day Cassandras are speaking up about climate change and its role in producing superstorms. But will they be believed before it’s too late?

— Scott O’Reilly

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