Top 5 ways Man-made Climate Change made Hurricane Harvey much Worse

By Juan Cole | (Informed Comment) | – –

The images from Houston and its environs are heart-breaking and we at IC wish all those affected a speedy and safe return to normality.

Extreme weather events are associated with climate change, and whenever they occur, they raise the question of their relationship to that process.

Human-induced climate change did not “cause” Hurricane Harvey. There have after all been hurricanes in the Gulf of Mexico all along, and some of them have been monstrous. So can we relate Hurricane Harvey to human pumping of carbon dioxide and methane into the atmosphere by driving cars, heating or cooling buildings, etc.?

The answer is “yes.” Climate change did not produce Harvey the Hurricane, but climate change made Harvey worse than it would otherwise be. Maybe 30% worse. That is, if Harvey dumps 4 feet of water on the Houston area in 2017, that suggests it would only have dumped 2.64 feet of rain if it had arisen in the 1749 hurricane season when Spanish settlers in Texas made peace with the Lipan Apache tribe.

That is because in 1749, there were 270 parts per million of carbon dioxide in the atmosphere and today there are 410 ppm of CO2. The parts per million of carbon dioxide in the atmosphere have fluctuated between 200 and 270 for the last 800,000 years . Homo Sapiens Sapiens is only about 200,000 years old, so this is the only climate we’ve ever known. Starting in the late 1700s, human beings started behaving like a global bank of super-volcanoes, spewing greenhouse gases into the atmosphere faster than had ever occurred in the history of the earth. Hundreds of billions of metric tons of carbon dioxide, through the burning of massive amounts of coal, as well as petroleum and natural gas. Ordinarily, going from 270 ppm of CO2 to over 400 would take millions of years of heightened vulcanism.

ghg-concentrations-figure1-2016 h/t EPA

One of the foremost experts in climate science, Professor Michael Mann of Penn State, explained how human-caused climate change made Harvey worse:

1. The sea off the Texas coast is half a foot higher than it used to be, because of global heating. Hotter water expands to fill more space, and melting surface ice that used to be on the land mass of Antarctica and Greenland and is now in the oceans as extra water and caused the sea level to rise. (The level of the land can also be lowered by e.g. drilling for oil). When the sea level is higher, that allows higher storm surges, leading to extra flooding.

2. The increase in the surface temperature of the ocean over the mid-20th century by about 1 degree Fahrenheit increased the amount of moisture in the air above it by 3-5%. More moisture in the air means that when it rains, it really pours.

3. The water in the Gulf of Mexico is warmer than a few decades ago, and warm water feeds hurricanes the way anger feeds the Incredible Hulk. Harvey was significantly more intense as a storm because it developed over warmer water.

These three causes are rock solid and without much doubt about them.

Mann points to a couple of other likely but not certain ways global heating made Harvey worse.

4. Climate Change contributed to a stronger high pressure system in the Gulf of Mexico, which pushed the jet stream north and allowed Harvey to malinger in Houston’s area instead of being pushed away by strong winds from dry land. The winds were left weakened by the migration north of the Gulf Stream.

5. Global heating seems to contribute to longer-term stationary weather patterns. Thus, the long-term drought in the US Southwest was exacerbated by this tendency. Harvey might not have stayed where it was so easily without climate change.

Mann’s conclusion that climate change made Harvey worse is chilling. Because we’re only at the beginning of global heating. There is a long lag between the time you burn the coal and the time the surface of the earth heats up (we are talking about average temperatures, and the oceans are cold and heat up very gradually). We are already locked in to going up another 2 degrees Fahrenheit, and now with Trump and Scott Pruitt turning the US into one big bonfire, we’re probably going up 4-5 degrees Fahrenheit. That amount of global heating could be catastrophic. The jury is out on whether much hotter oceans will produce more hurricanes or not. What is certain is that the ones that are produced will be much more intense.


Related video added by Juan Cole:

Democracy Now! “Climate Change Makes Storms like Harvey More Severe”

8 Responses

  1. Trump’s announcement of US withdrawal from the Paris Accord seems to have confirmed the determination of all the other signatories to make it work. Add to that the fact that the US is a complex society where city and state governments and many corporations can decide to honour the Accord despite the decision of the federal Administration. We are locked in to some temperature increase but we may be heading towards some control of the amount of increase.

    • .

      The French have lead the way recognizing Soil Carbons’ value and committing to build Soil Carbon by 0.40% annually. Putting them on the road to Carbon Negativity before any industrialized country. 25 nations have signed on to 4p1000. 100 of the 196 countries in Paris submitted plans to reduce CO2 via agriculture, forestry and placing soil carbon into their programmes.
      link to

  2. Voting against one’s self-interest has entered into a new realm of crazy. Unless we’ve horribly misidentified how humans assess self-interest, unless rational actor models are useless, unless the “utility” that utilitarians expect us to seek is the endurance of our suffering offset by the pleasure of watching those different than us suffer more.

    How, then, can scientific evidence sway us? It will always be easier in the short term to preserve the status quo, or even turn the clock back, than to invest in a future where one’s own caste status is yet to be determined.

    I’m here in Houston, watching the local media engage in endless self-congratulation of Texans’ willingness to help each other. As if that weren’t a form of indoctrination to tell us that we’re superior to the socialistic hordes beyond our borders, even as we dismantle the government that we formerly paid to do a better job of helping than a bunch of self-righteous amateurs with guns and Bibles. When the floods have subsided, we will go back to our chemical plants poisoning each other so we can buy goodies on credit, we will let the Black babies starve out of sight, we will labor mightily to blame all our problems on the Other in preparation for our schemes of eradication and purification.

  3. Climate change mitigation is less the issue than meaningful climate change mitigation response times. Please see:

    link to

    There is a timetable past which even a “national war footing” effort would be inadequate. Personal motivation requires that one begin counting backwards, not forwards.

    I must assume that Trump is not counting at all.

  4. Well stated.

    With regard to point 5, weather systems move along from west to east in Rossby waves. With less of a temperature difference between the equator and the poles the Rossby waves slow down. That is calculation using a simplified Terra model.

    So the question is whether or not the model is over simplified. Experience this century suggests not. I opine that Professor Mann is being overly cautious.

  5. As the planet warms from CO2 emissions and the atmospheric humidity levels rise, Harvey is just the kind of weather that we can expect to see more of. Ocean waters are warming and rising. Monster storms are brewing. The great irony in all of this is that the city of Houston is the oil capital of Texas and as such has benefited greatly from the American oil industry. It is the USA’s fourth largest city and a major CO2 facilitator emitter.

    Oh yes, I should add that CO2 is also the cause of the methane now bubbling out of the Arctic. Very large methane hydrate deposits exist below the Arctic land and adjacent ocean areas. Scientists say they represent 100 times the amount needed to cause another Permian style major planetary extinction event.

    This methane hydrate feedback loop will begin to “kick in” after a 2 C degrees (3.6 F) increase in global temperatures. Our civilization is approaching that 2 C figure. Global temperatures throughout the planet will then rise rapidly. Many scientists are telling us that as a result the feedback loop, temperatures far in excess of 4 C degrees are predicted due to a runaway increase in Methane. Over a 100-year timeframe methane is about 35 times more potent than carbon dioxide, over 20 years 84 times more potent.

    If you think Houston has a problem, just wait; you my Donald Trump skeptical friends and your progeny do too.

  6. … and the city ground is covered with hard surfaces there is no ability or place for the water to be absorbed – the combination adds up to devastation. Let’s make better choices now.

  7. With all due respect, hominids have been burning stuff for at least 1.6 MILLION years, not 200,000 years.

    link to

    Deforestation is the current historical primary climate-change driver, but uncontrolled use of fossil-fuels exasterbates the problem, greatly.

    30% of humans still employ firewood to cook and heat.

    link to

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