FacebookTwitterRedditEmail

Is Hurricane Harvey a Harbinger for America’s Future?

Over the past week we have seen two major tropical storms devastate different parts of the world. First Typhoon Hato struck Hong Kong and Southern China killing at least a dozen people. And over the weekend Hurricane Harvey made landfall from the Gulf of Mexico, bringing extremely heavy rain to southern Texas and causing devastating floods in Houston.

Tropical cyclones are, of course, a natural feature of our climate. But the extreme impacts of these recent storms, especially in Houston, has understandably led to questions over whether climate change is to blame.

How are tropical cyclones changing?

Tropical cyclones, called typhoons in the Northwest Pacific and hurricanes in the North Atlantic, are major storm systems that initiate near the Equator and can hit locations in the tropics and subtropics around the world.

When we look at the Atlantic Basin we see increases in tropical storm numbers over the past century, although there is high year-to-year variability. The year 2005, when Hurricane Katrina devastated New Orleans, marks the high point.

There is a trend towards more tropical storms and hurricanes in the North Atlantic. US National Hurricane Center

We can be confident that we’re seeing more severe tropical cyclones in the North Atlantic than we did a few decades ago. It is likely that climate change has contributed to this trend, although there is low statistical confidence associated with this statement.

What that means is that this observed increase in hurricane frequency is more likely than not linked with climate change, but the increase may also be linked to decadal variability.

Has Harvey been enhanced by climate change?

Unlike other types of extreme weather such as heatwaves, the influence of climate change on tropical cyclones is hard to pin down. This is because tropical cyclones form as a result of many factors coming together, including high sea surface temperatures, and weak changes in wind strength through the depth of the atmosphere.

These storms are also difficult to simulate using climate models. To study changes in tropical cyclones we need to run our models at high resolution and with interactions between the atmosphere and the ocean being represented.

It’s much easier to study heat extremes, because we can do this by looking at a single, continuous variable: temperature. Tropical cyclones, on the other hand, are not a continuous variable; they either form or they don’t. This makes them much harder to model and study.

Tropical cyclones also have many different characteristics that might change in unpredictable ways as they develop, including their track, their overall size, and their strength. Different aspects of the cyclones are likely to change in different ways, and no two cyclones are the same. Compare that with a heatwave, which often have similar spatial features.

For all these reasons, it is very hard to say exactly how climate change has affected Hurricane Harvey.

So what can we say?

While it’s hard to pin the blame for Hurricane Harvey directly on climate change, we can say this: human-caused climate change has enhanced some of the impacts of the storm.

Fortunately, in Harvey’s case, the storm surge hasn’t been too bad, unlike for Hurricanes Katrina and Sandy, for example. This is because Harvey did not travel as far, and weakened rapidly when it made landfall.

We know that storm surges due to tropical cyclones have been enhanced by climate change. This is because the background sea level has increased, making it more likely that storm surges will inundate larger unprotected coastal regions.

Building levees and sea walls can alleviate some of these impacts, although these barriers will need to be higher (and therefore more expensive) in the future to keep out the rising seas.

Deluge danger

Harvey’s biggest effect is through its intense and prolonged rainfall. A low pressure system to the north is keeping Harvey over southern Texas, resulting in greater rainfall totals. The rainfall totals are already remarkable and are only going to get worse.

We know that climate change is enhancing extreme rainfall. As the atmosphere is getting warmer it can hold more moisture (roughly 7% more for every 1℃ rise in temperature). This means that when we get the right circumstances for very extreme rainfall to occur, climate change is likely to make these events even worse than they would have been otherwise. Without a full analysis it is hard to put exact numbers on this effect, but on a basic level, wetter skies mean more intense rain.

Houston, we have a problem

There are other factors that are making this storm worse than others in terms of its impact. Houston is the second-fastest growing city in the US, and the fourth most populous overall.

As the region’s population grows, more and more of southern Texas is being paved with impermeable surfaces. This means that when there is extreme rainfall the water takes longer to drain away, prolonging and intensifying the floods.

Andrew King is an Climate Extremes Research Fellow at the University of Melbourne

This article was originally published on The Conversation.

More articles by:

Weekend Edition
March 22, 2019
Friday - Sunday
Henry Giroux
The Ghost of Fascism in the Post-Truth Era
Gabriel Rockhill
Spectacular Violence as a Weapon of War Against the Yellow Vests
H. Bruce Franklin
Trump vs. McCain: an American Horror Story
Paul Street
A Pox on the Houses of Trump and McCain, Huxleyan Media, and the Myth of “The Vietnam War”
Andrew Levine
Why Not Impeach?
Bruce E. Levine
Right-Wing Psychiatry, Love-Me Liberals and the Anti-Authoritarian Left
Jeffrey St. Clair
Roaming Charges: Darn That (American) Dream
Charles Pierson
Rick Perry, the Saudis and a Dangerous Nuclear Deal
Moshe Adler
American Workers Should Want to Transfer Technology to China
David Rosen
Trafficking or Commercial Sex? What Recent Exposés Reveal
Nick Pemberton
The Real Parallels Between Donald Trump and George Orwell
Binoy Kampmark
Reading Manifestos: Restricting Brenton Tarrant’s The Great Replacement
Brian Cloughley
NATO’s Expensive Anniversaries
Ron Jacobs
Donald Cox: Tale of a Panther
Joseph Grosso
New York’s Hudson Yards: The Revanchist City Lives On
REZA FIYOUZAT
Is It Really So Shocking?
Bob Lord
There’s Plenty of Wealth to Go Around, But It Doesn’t
John W. Whitehead
The Growing Epidemic of Cops Shooting Family Dogs
Jeff Cohen
Let’s Not Restore or Mythologize Obama 
Christy Rodgers
Achieving Escape Velocity
Monika Zgustova
The Masculinity of the Future
Jessicah Pierre
The Real College Admissions Scandal
Peter Mayo
US Higher Education Influence Takes a Different Turn
Martha Rosenberg
New Study Confirms That Eggs are a Stroke in a Shell
Ted Rall
The Greatest Projects I Never Mad
George Wuerthner
Saving the Big Wild: Why Aren’t More Conservationists Supporting NREPA?
Norman Solomon
Reinventing Beto: How a GOP Accessory Became a Top Democratic Contender for President
Ralph Nader
Greedy Boeing’s Avoidable Design and Software Time Bombs
Tracey L. Rogers
White Supremacy is a Global Threat
Nyla Ali Khan
Intersectionalities of Gender and Politics in Indian-Administered Kashmir
Karen J. Greenberg
Citizenship in the Age of Trump: Death by a Thousand Cuts
Jill Richardson
Getting It Right on What Stuff Costs
Matthew Stevenson
Pacific Odyssey: Puddle Jumping in New Britain
Matt Johnson
The Rich Are No Smarter Than You
Julian Vigo
College Scams and the Ills of Capitalist-Driven Education
Brian Wakamo
It’s March Madness, Unionize the NCAA!
Beth Porter
Paper Receipts Could be the Next Plastic Straws
Christopher Brauchli
Eric the Heartbroken
Louis Proyect
Rebuilding a Revolutionary Left in the USA
Sarah Piepenburg
Small Businesses Like Mine Need Paid Family and Medical Leave
Robert Koehler
Putting Our Better Angels to Work
Peter A. Coclanis
The Gray Lady is Increasingly Tone-Deaf
David Yearsley
Bach-A-Doodle-Doo
Elliot Sperber
Aunt Anna’s Antenna
March 21, 2019
Daniel Warner
And Now Algeria
FacebookTwitterRedditEmail