Six Questions for State Climatologist John Nielsen-Gammon
The Great Drought, climate change, and Rick Perry
This is Part Seven in an occasional series of Q&As with Texans involved in issues of the environment and energy. (Read Part One with Bee Moorhead here, Part Two with Andy Sansom here, Part Three with Katherine Hayhoe here, Part Four with Patrick Kennedy here, Part Five with Michael Banks here and Part Six with Gabriel Eckstein here.)
John Nielsen-Gammon has a tough job. As state climatologist, he’s paid a pittance to keep tabs on Texas’ wonderfully (and scarily) schizophrenic climate, where we seem to be either baking in the pits of hell or on the verge of being flooded away, where El Paso in the west get 8 inches of rain a year and parts of East Texas get 40-plus inches, where climate change is already creating “new normals” and hurricanes, hail, tornados and even freaky winter weather are a way of life.
He’s called on frequently to predict rain, to explain climate change, to tell us just how bad this or that drought is, and respond to pitches from would-be rainmakers. He’s even undertaken a peer-reviewed journal article on the scientific accuracy of Al Gore’s Inconvenient Truth. He keeps a blog at the Houston Chronicle called “Climate Abyss,” which is updated – I’m ashamed to admit – much more frequently than this one.
And, most important, he’s a guy who likes to stick to the facts, rather than reinforce political beliefs.
Nielsen-Gammon has been state climatologist – a position he handles from his academic perch at Texas A&M – since 2000. With an awful drought and a looming climate crisis (in my opinion), I put six questions to John Nielsen-Gammon. Our Q&A follows:
TO: You recently wrote that the current drought is the third-worst in recorded Texas history. What’s the outlook in the mid- to long-term? How much worse could things get?
JNG: The all-time record driest 12 consecutive months in Texas was October 1955 through September 1956, when the state received on average 13.69 inches of precipitation. Coincidentally, our current dry streak started in October too, and through June the state has received close to 8.5 inches. Normal for July through September is 7.69 inches. So if we begin seeing normal precipitation as of July 1, we’ll end up nowhere near the 1956 drought’s severity, notwithstanding the fact that 1951 through 1955 were also drought years.
I’d say Texas would need to come in around 11 inches for it to be ranked as the #1 drought in the state. Not likely, but possible. Alternatively, if the drought continues for another couple of years, it could become #1 that way, and just watch the problems that develop with water supplies in summer 2012 under that scenario!
Summertime precipitation is very difficult to predict in Texas. One of the key factors is soil moisture, so the fact that we’re starting this summer exceptionally dry means that we are likely to receive below-normal precipitation in summer too. The only assuredly good news on the horizon is the probable lack of another La Nina this winter. Normal to El Nino conditions ought to bring normal to above normal rainfall this winter. Of course, there are no guarantees.
TO: Also, relatedly: we typically compare droughts to the ‘drought of record’ in the 1950s but there is evidence, such as tree-ring data, that indicates that parts of Texas experienced even longer, more intense dry spells in the past.
What would a repeat of such a drought look like today, given the enormous demands?
JNG: There are already some issues arising with water-intensive crops such as rice. There would be permanent irrigation water shortages if we get one of those mega-droughts. There may also be serious issues for certain small water suppliers. We shouldn’t see any major metropolitan areas running out of water, though, but people will have to disabuse themselves of the notion that yards and landscaping are good uses for drinking water.
TO: To what extent, if any, can we link this drought to climate change?
La Nina, the primary trigger for the current drought, may or may not increase or decrease in frequency or intensity, so that part is a big fat “we don’t know”. As to why this particular drought was so severe, understanding it will require model simulations investigating various aspects of the ocean temperature patterns and so forth. Probably no connection to global warming, but who knows?
The fact that we’re comparing this drought to droughts in the beginning and middle of the 20th century is a hint that we’re not in unprecedented territory and climate change does not need to be invoked as an explanation. Climate change is, however, a force multiplier. We are a couple of degrees F warmer than we would be without recent global warming, so fires are more likely, crops need more water, and the weather is that much more unpleasant. In the combination of dryness and (especially) heat, this drought is unprecedented.
TO: Do you agree with Texas Tech climate scientist Katharine Hayhoe that the recent extreme weather events are part of “global weirding,” an increase in extreme weather events driven by climate change?
I don’t like to paint all unusual weather events with the same broad brush. “Weird” simply means “I don’t remember it happening before.” And some extreme weather events will become less common. Is a drought as severe as the one in 1918 weird? Sure, because it happens so rarely. But the mere fact that it happened 92 years ago implies that our atmosphere is quite capable of doing this without global warming. The same applies to the megadroughts that show up in the tree ring records.
I prefer to think of climate change as a force multiplier. Driest nine consecutive months in history? Sure, but warm global temperatures have accelerated the evaporation and made this drought a bit hotter and more severe than it would otherwise be. Summertime flooding? It would be kind of nice, and global warming would have added a little bit of moisture and a little bit of rainfall.
TO: Looking forward 50 years, what will Texas’ climate look like under a business-as-usual emissions scenario, that is, if the world does nothing to curb greenhouse gas emissions?
Assuming business-as-usual greenhouse gas emissions and no notable changes in solar output or volcanic activity, Texas will be a good bit hotter, about 3-4F on average. We don’t have a good handle on precipitation yet (models say probably drier, but the historical record trends upward), but even with the same amount of precipitation, the increased temperatures will make everything drier. Combine that with increased population’s demand on water supplies, and there will be a lot less water in creeks and rivers. This will affect bay and estuary health, and the high temperatures will affect ozone pollution by making it worse in general. We don’t know this down to the regional detail, but hurricanes in the Atlantic Basin could be less common, but with the occasional super hurricane beyond what we would normally see.
If the world institutes significant curbs on greenhouse gas emissions, the Texas climate will be similar to my description of business-as-usual above. The impacts of greenhouse gas restrictions only start playing a major role after mid-century.
TO: Let’s move a bit into the space where science and politics intersect, always a fun place to be! Gov. Perry has made it abundantly clear over the years that he does not believe global warming, man-made or not, is even occurring, a fairly extreme statement even in the ‘denier’ community.
He’s also cast aspersion on the science itself. For example, in his recent book *Fed Up!*, he made the following statements:
“we have been experiencing a cooling trend”;
“draconian policies with dire economic effects based on so-called science may not stand the test of time,” and;
“when science gets hijacked by the political Left we should all be concerned.”
(pg. 92 of *Fed Up!*)
As state climatologist, what do you make of these statements? Are you troubled that these positions undermine public confidence in the integrity and objectivity of science?
JNG: I have never actually heard (or seen in print) Gov. Perry state a position on the key scientific findings of the IPCC, such as that global warming is real and that a primary cause is increasing greenhouse gases, except once when making a joke. His public statements in this area, as with most of his public statements, are generally those of a master politician, finely calibrated to attract public approval while tipping as little of his hand as possible. So it is true that there has been a cooling trend for the past several years and that some have said that certain scientific results compel us to take particular policy actions.
Gov. Perry may well believe that global warming is real and man-made, but while he’s arguing political points I really can’t imagine him saying something like “the cooling trend for the past several years is almost certainly only temporary and hasn’t come anywhere close to cancelling the warming trend of the previous forty years”. I accept that as reflective of the present state of political discourse, but as a scientist, I don’t like it. I prefer that what’s well-established science be agreed upon as well-established science, and what’s still tentative science be recognized as tentative science.
I would also be more comfortable if he or his aides were actually consulting with unbiased expert scientists while forming their opinions regarding climate change. Since I’m the most obvious choice for an unbiased expert scientist in this area, and haven’t been consulted, I can’t help but be concerned about the source of his information. Again, I don’t know that he’s wrong about any of the science related to climate change, but I don’t know that he’s right about it either.
Likewise, I haven’t heard him criticize science or scientists in general, only particular uses of science for political purposes. As long as he keeps walking that fine line, I don’t have a problem with it as a scientist.