Warming-Enhanced Texas Drought Is Once in “500 or 1,000 Years … Basically Off the Charts,” Says State Climatologist

Leading experts explain how human-caused warming exacerbates the drought

“With no previous points so dry it’s hard to say exactly what history would say about a summer such as this one.  Except that this summer is way beyond the previous envelope of summer temperature and precipitation.” — Texas State Climatologist John Nielsen-Gammon

From October of 2010 through this September 2011, Texas saw its driest year on record, according to the National Oceanic and Atmospheric Administration.

But these historic dry conditions stretch back even further than that.

After examining tree-ring data going back to 1550, researchers at Columbia University found that this year’s drought was only rivaled once in the last 461 years. According to the Palmer Drought Severity Index, a system for measuring wet and dry conditions, the last time Texas experienced a drought this bad was in 1789.

The state’s climatologist, John Nielsen-Gammon, explained the historical significance of the ongoing drought in an interview with CBS:

“This is basically off the charts. Based on past history, you wouldn’t expect to see this happening in maybe 500 or 1,000 years.  One more year and we’re already talking about a drought more severe than anything we’ve ever had. And this will become for them, the drought of record.”

The drought, which Nielsen-Gammon says could stretch over a number of years, has devastated cotton crops, livestock, pumpkin crops, and, as the below CBS story points out, Christmas trees. The dry conditions have been exacerbated by a combination of human-caused global warming and La Niña, which pushes unusually cold air from the Pacific Ocean and causes drier-than-average conditions in the Southern U.S.

A number of leading climate experts recently explained the role that they believe human-caused global warming is playing in this epic drought.


As Texas climatologist Katherine Kayhoe put it in an email to Climate Progress, dumping ever-increasing amounts of greenhouse gases into the atmosphere is setting the conditions for turning extreme-weather events into history-setting catastrophes:

We often try to pigeonhole an event, such as a drought, storm, or heatwave into one category: either human or natural, but not both. What we have to realise is that our natural variability is now occurring on top of, and interacting with, background conditions that have already been altered by long-term climate change.

As our atmosphere becomes warmer, it can hold more water vapor. Atmospheric circulation patterns shift, bringing more rain to some places and less to others. For example, when a storm comes, in many cases there is more water available in the atmosphere and rainfall is heavier. When a drought comes, often temperatures are already higher than they would have been 50 years ago and so the effects of the drought are magnified by higher evaporation rates.

The Why Files has comments on the drought from many leading experts:

Gammon:  “There is evidence that global warming has had an effect on the drought, primarily by increasing the surface temperature, which increases the drought severity by increasing evaporation and water stress, and by decreasing stream flow and water supply….

… “temperatures have been rising in Tex over past 30 years or so, and they are projected to continue rising at similar rates. We think that the hole is filling, and I am afraid of a rebound effect, where natural variability varies in the opposite direction and the temperature rise would be relatively rapid.”

Richard Alley, professor of geosciences, Earth and Environmental Systems Institute, The Pennsylvania State University

It sure looks like warming, wrote Richard Alley, an expert on climate and ice at Pennsylvania State University, via email. “Our usual scientific response is to say that human burning of fossil fuels has made the events more likely, and they happened,” but conclusive proof is not available. “You as journalists, and the public in general, HATE that. But it’s probably the best answer.

“In a warmer world, we expect more record highs and fewer record lows, more heat waves and fewer cold snaps. That pattern is being observed. Warmer air can ‘hold’ more water (saturation vapor pressure increases with temperature), so if air is warmer when a rainstorm happens, then the rain can be more intense.

“In addition, there is a fairly strong reason to expect that in a warming world the subtropical dry zones (which include the Sahara and the Kalahari, and influence the U.S. Southwest, including parts of Texas) will intensify and expand poleward at least somewhat.

“Suppose you’re playing dice with me, and after you lose, you discover that I stuck some carefully positioned weights inside them. Out in the climate, the dice are now loaded, but not nearly as much as they will be in the future if we keep burning fossil fuels and releasing the CO2 to the air. It is hard to prove that any particular event was extreme because of global warming … but for many events (record heat, drought and flood) it is harder to prove that humans did not influence the outcome, just as it is very hard to prove that my loaded dice didn’t affect the game.”

Kevin Trenberth, distinguished senior scientist, National Center for Atmospheric Research

Is the Texas drought and heat wave due to climate change or natural variation? “There is no doubt a modest component related to climate change, while natural variability plays a major role,” says Kevin Trenberth, a climatologist at the National Center for Atmospheric Research. “Fifteen years ago we suggested that with ENSO [El Nino-Southern Oscillation; periodic variations in water temperatures in the Pacific] the floods and droughts would become more intense.”

… Although the drought is linked to La Nina, it is also exacerbated by climate warming, Trenberth adds. Human climate change adds “about a 1 percent to 2 percent effect every day in terms of more energy. So after a month or two this mounts up and helps dry things out. At that point all the heat goes into raising temperatures. So it mounts up to a point that once again records get broken. The extent of the extremes would not have occurred without human climate change.”

U.S. and Mexico map, large black area over Texas, Oklahoma, New Mexico and Northern Mexico indicates most extreme dryness

In short, Texas ain’t seen nothing yet, assuming we keep listening to their politicians….

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27 Responses to Warming-Enhanced Texas Drought Is Once in “500 or 1,000 Years … Basically Off the Charts,” Says State Climatologist

  1. David Sheridan says:

    Texans are receiving cosmic payback for re-electing Perry. Once he’s gone, they’ll get some rain, unless they elect another dimwit.

  2. Colorado Bob says:

    ” And the costs are high. Drought-related losses to property, farmland and livestock in Texas have topped $9 billion. ”

    Read more:

    “There’s hundreds of thousands of trees dying,” said Travis Miller, a drought expert at Texas A&M University.

    “We’re looking at a … one-in-a-500-year kind of drought, and so it’s weeding out the ones that can’t survive this kind of extreme conditions,” he added.

  3. Colorado Bob says:

    Forget lawn watering or car washing: A drought has dried up even drinking water supplies for an estimated 2.5 million people in more than 1,500 small communities in northern Mexico.

  4. Colorado Bob says:

    The lack of rainfall has affected almost 70 percent of the country and northern states like Coahuila, San Luis Potosi, Sonora, Tamaulipas and Zacatecas have suffered the most acute water shortage.

    Due to the drought and a cold snap at the start of the year, the government has cut its forecast for corn production two times in 2011. It now expects a harvest of 20 million tonnes compared to a previous estimate of 23 million.

    Crops that cover tens of thousands of acres have been lost this year and roughly 450,000 cattle have died in arid pastures. Crucial dams, typically full at this time of year, are at 30 to 40 percent of capacity.

  5. BA says:

    Texas is Geo-political shorthand for a much larger area. Look at the map above and the area covers perhaps most of northern Mexico, and a good portion of New Mexico, Oklahoma, and sizable chunks of Arizona and Kansas. As one of the quotes says:
    “In addition, there is a fairly strong reason to expect that in a warming world the subtropical dry zones (which include the Sahara and the Kalahari, and influence the U.S. Southwest, including parts of Texas) will intensify and expand poleward at least somewhat.”

  6. Pangolin says:

    The question I never see answered is this: if it doesn’t actually rain in Texas then what happens? Where does the water come from to support millions of people?

  7. climatehawk1 says:

    Oops, Katharine Hayhoe, not Kahoe.

  8. Joan Savage says:

    Original tallgrass prairie vegetation has perennial roots typically 8 to 15 feet deep that survive most drought conditions.

    “Of 20 million acres of beautiful Texas tallgrass prairie, less than 1% now remains due to suburban sprawl, plowing for row-crop agriculture, and improper overgrazing during the last 150 years.”

    This does not bode well for preventing soil erosion, Dust Bowl style.

  9. Colorado Bob says:

    ” Where does the water come from to support millions of people? ”

    We’re about to find that out.

  10. Stephen Lacey says:

    Oops! Fixed. Thanks!

  11. Mulga Mumblebrain says:

    There’s a synergy. Drought kills trees, making things worse in so many ways. The answer would, in small part, be to plant billions of trees, but where’s the money in that?

  12. Mulga Mumblebrain says:

    They’ll probably have to drain the fossil water supplies in the groundwater, I suspect(if the fracksters haven’t polluted it beyond human usefulness).

  13. BBHY says:

    People will eventually move to other parts of the country.

  14. Colorado Bob says:

    70% of Mexico is drought, I knew they were suffering, but news about it has been very thin. I took to calling this “The Great Texas Drought ” months ago. But the stories linked at two and three, Have moved me to add a word.
    “The Great Texas-Mexican Drought “

  15. Colorado Bob says:

    Looking at all that black spilling down into Mexico, the Monarch and bird migrations, will be a terrible total.

  16. Colorado Bob says:

    Link @ #4 –

    In the northern state of Durango, where a third of the population lives in the countryside, authorities expect significant losses in grain and seed production as well as bean and corn, which are a staple in the Mexican diet.

    “It’s a tragedy because there is virtually no harvest. It’s a critical situation that we don’t even have beans for home consumption,” the state governor Jorge Herrera told Reuters.

    Official figures show an expected 28 percent loss in production of beans this year, while the recovery to historical levels of 1.2 million tonnes will depend on the weather.

    If the drought does not lift soon, analysts say authorities will be forced to raise its food imports to cover lower domestic production.

  17. Lou Grinzo says:

    The loaded dice metaphor is good, but I think a slightly better one is driving under the influence of alcohol. Take one drink, and you’re still legal to drive, and you’ve likely increased your odds of having an accident by a very small or negligible amount. Take a second and third and … drink, and the odds keep going up that you’ll not just have an accident and crease some sheet metal but injure yourself and/or other people who had nothing to do with your deplorable behavior. Eventually, you’re so drunk that the odds of having an accident, even over a very short trip, are virtually 100%.

    Right now, certain portions of humanity have become the guy at a bar or party who’s had several drinks too many and is belligerently refusing to call a cab for his ride home or sleep it off on a friend’s couch. Everyone else can see the disaster coming, but the loudmouthed, arrogant drunk refuses to listen as he staggers toward his car and fumbles for the keys in his pocket….

  18. M Tucker says:

    I have noticed that no matter what stupid nonsense Republicans and conservatives might say about global climate disruption at the national level, and no matter what sort of ignorant glad-handing buffoon might be Governor, city leaders must and will respond to the crisis and begin to prepare for the worst. The Georgetown Climate Center in DC is committed to helping and the cities with the economic wherewithal to respond are already planning for the worst. But, folks living in a desert environment faced with a decade (or much more) long drought, may have to take refuge elsewhere.

  19. prokaryotes says:

    If you are in the Texas area you better plan relocation in the coming years…

  20. Spike says:

    Nothing by Texas standards but still very dry in UK and France

  21. a face in the clouds says:

    It’s come down to cutting trees to save water at Horseshoe Bay near Austin. (Link below) It’s only been just over a year since Tropical Storm Hermine passed through this same area and dropped more than a foot of rain in some places. Horseshoe Bay’s idea may catch on around the state in order to stem the mass die-off of trees currently underway.

    Officials at the nearby Highland Lakes are also seeking permission to cut off water to downstream farmers so city dwellers have enough to drink. The state is expected to approve the move next week.

    In the meantime, there are reports of climate refugees on the move in Northern Mexico. The government is calling the drought the worst in 70 years, but that is probably an understatement. The drought zone includes some hard country where water rationing has always been a way of life, but some 2.5 million people are now reportedly receiving emergency supplies. Heriberto Felix Guerra, whose agency is in charge of the emergency, said the drought is being “caused in large part by the climate change affecting the entire planet.”

  22. Robert Nagle says:

    What was the PDSI for the Texas region this summer? Anyone know?

  23. Uncle B says:

    Got Sun? Make Solar energy!