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John Nielsen-Gammon: The TT Interview

The Texas state climatologist on the reasons for rising temperatures, why international science on climate change is fundamentally sound (no matter what state officials say), what he thinks of our fight with the EPA and how long the drought in Central Texas is likely to continue.

John Nielsen-Gammon, Texas's state climatologist

A major international conference on combating climate change wraps up this week in Cancún, Mexico — and once again, little is likely to be accomplished. But Texas is hardly immune to the effects of increasing greenhouse gases, according to the state climatologist, John Nielsen-Gammon, who works out of Texas A&M University's Department of Atmospheric Sciences (he also blogs for the Houston Chronicle). Nielsen-Gammon expected the climatologist position, which he has held for 10 years, to be "fairly mundane," but it didn't turn out that way.

He spoke with the Tribune last Friday by telephone about the potential for rising temperatures in Texas, why international science on climate change is fundamentally sound despite challenges from state officials, and how long the drought in Central Texas is likely to continue. An edited and abridged transcript of the interview and audio follow.

TT: What exactly is a state climatologist?

Nielsen-Gammon: It's basically what you make of it. There's an association of state climatologists that specifies the basic characteristics. Your main role is to investigate, interpret and basically help apply climate knowledge to the problems of specific states. Sometimes that includes data gathering, product generation, interpretation of climate forecasts, outreach. We do a lot of data requests. We do a lot of public talks and that sort of thing.

The whole program got started in 1970s when the National Weather Service, in their semi-infinite wisdom, decided that climate services were not going to have any value in the future. Until that point, state climatologists were federal employees. Since then, states have gradually picked up the slack, so now about 48 out of 50 states have their own climatologists, which are generally in land-grant universities. 

TT: Is it a paid position by the state of Texas? 

Nielsen-Gammon: The state of Texas doesn't directly pay it; I get a supplement of a few thousand [dollars] a year for the extra administrative work. The university also supplies me with a budget for student and staff. But otherwise I don't get any direct state funding.

Audio: Interview With Nielsen-Gammon

TT: What [are] the broader effects of climate change here in Texas? I assume you think it actually happening already.

Nielsen-Gammon: Well, the climate always changes. So the trivial answer is yes, it's happening. The temperatures across the state over past century or so were gradually increasing until about the 1950s. They reached peak during drought years in the '50s, then dropped considerably. Some of coldest weather was in the '70s. Since then, they've generally been rising. Temperatures across the state are about 2 degrees warmer now Fahrenheit than they were in the mid-'70s on average. Some might be due to changes in urbanization and so forth, but they've tried to correct for that, so most of it, I expect, is real.

The overall pattern ... vaguely follows global pattern for temperature change, with warming in the early part of the century, then fairly flat in the middle and warming since then. It seems that a part of that is due to an increase in greenhouse gases. And the computer models — just atmospheric models — that are run with historical sea-surface temperatures give this same pattern, so basically you've got the sequence of events: the warming, the change in the radiative properties of the atmosphere affecting the ocean temperatures, which in turn affect things locally.

Now, there's a lot of natural variability that goes on top of that, so it's not really possible at this point to say what fraction is due to global warming, but based on what we know, it seems like a significant fraction of it is.

TT: You have predicted that temperatures in Texas — average temperatures — will rise by several degrees over 50 years. Is that right?

Nielsen-Gammon: Not quite right. What I said specifically is that the model projections [about the impact of greenhouse gases on climate] that are run for the IPCC [Intergovernmental Panel on Climate Change] have the temperatures rising in Texas from the present by an additional anywhere from 1 to 4 to 5 degrees by the middle of the 21st century. And the rate of rise projected there is similar to how rapidly temperatures have been rising since the 1970s, so it's at least plausible that that could happen. Part of the problem is there's a big range in that forecast, so it could go up a little or go up a lot. Even a little bit would put that warmer than anything we saw in the 20th century.

But those are just considering one factor involved in climate change. You'd also have to consider the effects of aerosols and volcanic activity and solar intensity and the Pacific Decadal Oscillation — all sorts of things we can't predict. So we don't know what temperatures will be like in 2050. What the projections tell us is basically the effect of greenhouse gases alone would give us that much warming. And the other factors could have just as big an influence, but it could go in either direction. Maybe they'll cancel the greenhouse warming and we'll stay about the same. Or they could be a positive factor on top of it. So those are the things that we can't predict.

TT: And your view is that the [increase in greenhouse gases] is largely caused by humans?

Nielsen-Gammon: The increase is definitely caused by humans.

TT: And in that potential warming model caused by greenhouse gases, within Texas is there likely to be any regional variation?

Nielsen-Gammon: The regional variation will come from the other effects, not the greenhouse gases per se. The greenhouse gas effects will be fairly uniform. The specific pattern of temperature change depends a lot on the specifics of how the ocean temperatures evolve. Even in the past century, the rise has not been uniform across the state. East Texas is still cooler than it was in early part of 20th century, whereas South Texas is quite a bit warmer than it has been. So there's already quite a bit of variation. Likewise, that variation is not predictable either, so it may be that East Texas will catch up, and it may be that the pattern will persist. We just don't know.

TT: Texas is the state probably most resistant to implementing federal carbon-dioxide or greenhouse gas regulation that's coming in next year from the Environmental Protection Agency. Do you have a view on the petitions filed by the attorney general that dispute the international science behind the EPA's actions?

Nielsen-Gammon: I can't address the specific legal argument that attorney general is making because I'm not a lawyer. They're basically saying the EPA is obligated by law to do its own review, rather than relying on outside reviews like the IPCC. That may be a good argument or not — I don't know. However, it's probably unlikely that the EPA would come up with something much different from the IPCC, because based on my reading of their report, it's pretty good as far as science goes. I agree with about 95 percent of what is written [in the IPCC report]. It's not perfect, but it's about as good as it's going to get. So I don't think having the EPA do its own independent review from ground zero would change things other than perhaps delaying implementation by a couple of years.

TT: Is there anything within that 5 percent that you specifically disagree with, or is that just a general comment?

Nielsen-Gammon: Well, it's general based on the parts I know. The mistake they made about the Himalayan glaciers was fairly shoddy, and I actually publicized that in my blog about a month before it hit the presses; I wasn't the one to discover it. But that was basically a consequence of scientists talking outside their area of expertise. If you go to the part of the report that's written by glaciologists, they got things right. So it varies a bit. And then for some controversial subjects, you tend to have not necessarily a perfect balance of scientific viewpoints among the people writing things. So for  example, with respect to impact of changes in hurricanes, I think the IPCC report goes a little bit farther in terms of hurricane changes than present scientific consensus has it.

TT: Have you had any push-back from politicians in the state on your work?

Nielsen-Gammon: No, I haven't. I've testified before the Legislature a couple of times in connection with particular bills, such as one last session that would have required us to evaluate climate change adaptation plans by state agencies. But certainly no push-back in terms of what I'm doing as far as interpretation of climate science and outreach. I'm a little bit concerned bout some of the things I see on websites from some elected representatives about the whole of climate science being a hoax, or things like that. I think there's a lot of things that are disputable about what's going to happen in the future with climate change, and there are a lot of things about how the climate system works that we know very well. And I think it's very important to distinguish between two things. And I really want to make sure that the people who are setting policy understand what the knowns are and what the unknowns are.

TT: Is there anything Texas should be doing to prepare for climate change?

Nielsen-Gammon: Well, the good news about preparation is that climate change is a slow process. The impacts happen relatively suddenly, though. For example, there are two main factors in Texas affecting sea-level rise. The most important one is land surface subsidence, through freshwater pumping and other factors. Second in importance is the global sea-level rise due to climate change. But the cause doesn't really matter for adaptation purposes. Where sea-level rise has an impact is not the gradual up-creep of the shoreline but the sudden change of shorelines associated with major hurricanes and other storms that have reconfigured the coast. So the manifestation of sea-level rise on Texas is going to be essentially not much happening for a long time, then suddenly a big change, then not much happening and so forth. Infrastructure needs to basically plan for the net effects of sea level rise for anything that's supposed to last for decades. [So] major ports and shipping facilities have to be able to able to adjust for the likelihood that over the next several decades, the local sea level's going to be increasing by a foot or more. And that's likely to continue.

The other big adaptation that's probably going to take place is in terms of agriculture. As the climate changes, the crops that are viable or most profitable change also. That sort of thing, farmers have been adjusting to for years. There are periods of times when citrus was growable in certain areas, and periods of time when it wasn't. Farmers can be on their toes and forward-looking about this. In other words, things that are presently marginal (because of cold temperatures in the wintertime) will gradually become more and more viable with time. And conversely, plants — agricultural products — that have difficulty with heat can be expected to have more difficulty in the future.

TT: Hurricanes — are we likely to see more of those with climate change?

Nielsen-Gammon: Presently, the models come up with about the same number of hurricanes or even fewer hurricanes. So the present thinking is that they're probably not going to become more frequent in the future; however, the ones that do develop will have the potential to become more intense. Just like temperatures, though even more so than temperatures — the details of that pattern will vary from region to region, because there are other things besides temperatures that affect where hurricanes form and how they intensify. So for any given location, at this point, it's literally too early to tell whether the net effect of hurricanes would increase or decrease.

TT: We haven't had rain here in Central Texas for several months. What is causing that and do you have any sense for how long it will go on?

Nielsen-Gammon: We went into this fall and winter with the expectation that it was going to be dry, because we had unusually cold sea-surface temperatures in the eastern tropical Pacific. It's a phenomenon called La Niña. It's essentially the opposite of El Niño, which has warmer temperatures there. And that affects the thunderstorm pattern over the whole of the Pacific, and that in turn affects the jet-stream pattern and so forth. The bottom line is when that happens most of the time Texas — and, for that matter, just about all the U.S. — ends up having a relatively warm and relatively dry winter. So that part was not a surprise. It's especially hit hard in Central Texas. Most of the Panhandle is doing fine, but otherwise, yes, the past couple of months have been dry. Looking at the numbers, it seems that in some places it may very well be [that this past] October and November were the driest on record [ever].

TT: Is it likely to continue — that dry winter — for awhile?

Nielsen-Gammon: It's unlikely it will stay this dry. I don't expect every month to be record-setting dryness. But it's certainly likely that we'll have below-normal rainfall going on. I've looked at a few of the cases in past, where we've had exceptionally strong La Niña events like we do now. It seemed like for them it was dryer in the fall than it was in the spring. So that's a little glimmer of hope, but it's still not going to be a particularly wet winter even if that pattern holds true.

TT: How did you get interested in climate science?

Nielsen-Gammon: If one decides whether a person's a climate scientist by whether they've published any research on climate, I became a climate scientist about three years ago, which was a while after I became the state climatologist. I got involved in becoming the state climatologist because I saw the connection between weather observations and weather and climate forecasts and data archives. My background is more in terms of weather forecasting, front storms, floods, that sort of thing. And I didn't really [anticipate] how important the changing climate was going to be. So I was expecting state climatologist to be a fairly mundane job, about helping to improve the data record and helping to archive information and so forth. But obviously it's become more and more important from a policy standpoint. I've educated myself quite a bit on the basics of climate science, and also the existing controversies, so I feel I'm in a position to provide good and objective advice to anybody who needs information on climate change.

And I guess part of that comes from my background. My doctoral degree is from MIT, and two of the faculty members on my committee were Kerry Emanuel and Richard Lindzen, who are presently basically not talking to each other because of their opposite views on climate change. So I've seen it from both sides.

TT: Anything else we should talk about?

Nielsen-Gammon: We talked about temperatures changing in Texas. Precipitation is also changing. People may have seen reports that the southwestern United States, including Texas, is getting dryer and going to become another Dust Bowl. There's some element of truth in that, but not a whole lot. Rainfall in Texas has actually been steadily increasing over the past century. It's about 10 to 15 percent more rainfall per year now than there was at beginning of 20th century, which is a fairly large amount. And the projections for rainfall change in the future from climate models — some have it wetter, most have it dryer. But none of the changes is as big as we've already seen. So the good news in that regard is we don't really need to worry about what climate change will do to rainfall because rainfall is already changing by a lot more than that.

The impact on water supply is going to come from the change in temperature, which increases evaporation, increases water demand and increases the need for water both by plants and by cities. So the changing climate is going to reduce water supplies, but that's a second-order effect compared to the increase in population, which is having a massive effect on demand for water. But as we know more and more about climate change, I think it becomes more and more important that we plan for the effect of a changing climate as well as plan for the effect of a changing population.

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