Katharine Hayhoe: The TT Interview

Weird weather has become a big topic in Texas, as the state continues to struggle with a record-breaking drought and unusually hot temperatures. The climate is also an issue on the presidential campaign trail, with Gov. Rick Perry asserting that he is a "skeptic" that humans are causing the world to warm.

Katharine Hayhoe, a climate scientist at Texas Tech since 2005, spends some of her spare time reaching out to community groups to convey the opposite — that humans are the main cause of climate change, and that ordinary people will feel its impacts. She was the lead author of a 2008-09 federal report, “Global Climate Change Impacts in the United States," and has also co-authored a book with a pastor titled A Climate for Change: Global Warming Facts for Faith-Based Decisions. She spoke with the Tribune about her work as a climate scientist in Texas. This interview has been edited and condensed.

TT: What got you interested in climate science to begin with?

Hayhoe: My undergraduate degree is in atmospheric physics. And so in studying atmospheric physics, it became apparent fairly quickly that one of the greatest issues related to atmospheric physics was the fact that humans are actually altering the content of our atmosphere, through putting more heat-trapping gases into our atmosphere than would normally be there, and those heat-trapping gases are affecting the climate of our planet.

TT: How certain is this [that humans are contributing to climate change]?

Hayhoe: The most recent survey I've seen found that almost 98 percent of scientists in related or relevant fields to climate science agreed that human production of heat-trapping gases was the main or most important influence on climate change today, and was responsible for much of the climate change that we've seen over the last 50 years.

TT: How have we seen climate change already in Texas?

Hayhoe: Well, first of all, starting at the global scale because it's a global issue, we have already seen that the planet's average temperature is increasing, and we have seen this in the U.S. as well. Both in the U.S. and at a global scale, we've seen that heavy rainfall levels are becoming more frequent. We've seen that we are breaking our high-temperature extreme records twice as frequently now as we're breaking our low-temperature extremes. ... Many other events, like heatwaves, have become more frequent and more severe. We're also seeing weather patterns that are less predictable and different than what we've seen before.

Here in Texas, we are also affected by sea-level rise. We have a long coastline along the Gulf of Mexico, and our sea level has already risen by 7 inches over the last 100 years or so, and we expect it to rise by a good deal more in the future. We aren't seeing any more hurricanes or tropical storms than we used to, but what we are are seeing is some indication that more of these storms might be stronger and have more rainfall associated with them. So you remember that tropical storm that we had recently. ... It had so much rainfall associated with it. ... The same with Hurricane Irene ... so we're [seeing] that our hurricanes are carrying more rainfall with them, and there's some indication that stronger ones may be becoming more frequent.

We are also seeing that the average humidity [has] increased because the warmer the air is, the more water vapor it can hold. Our precipitation patterns are shifting.

TT: Are we talking about Texas or the country?

Hayhoe: I'm talking about the country as a whole. The storm track — there's a storm track that usually runs along the northern part of the U.S. It is shifting northward toward the poles as the planet warms. And what we're seeing across the whole U.S. and here in Texas is ... how the natural environment responds to these changes. We are seeing that that tree species and flowers and plants are blooming earlier in the year. We are seeing all kinds of insect and bird and animal species move further north. People who lived in one place for a long time can tell you that 30 years ago we didn't see certain types of birds here. We didn't used to see certain types of insects ... but now, all across the U.S., if we look at our own backyards, we can see evidence of a change in climate.

TT: And what about the extent to which the current drought and extremely high temperatures that have been affecting Texas are related to climate change?

Hayhoe: That's the question that we all want the answer to... First of all, we have already altered the background conditions of our atmosphere, through increasing our production of these heat-trapping gases and increasing the average temperature of the atmosphere. ... We have changed the background conditions in terms of not just the temperature but the humidity and also the weather patterns that we've experienced. So in that sense, every event that happens — snowstorm, heatwave, drought, flood — every event that happens has some contribution or component of climate change in it, because we've changed the background conditions.

So now, about this current drought. There's no question that the main cause — the primary cause — of this drought that we've experienced is La Niña. Whenever it's El Niño, at least in West Texas, we have record rain events and flooding, and whenever it's La Niña, we have drought... That's just what happens. It's been happening for hundreds of years and it's a natural cycle. 

But can La Niña account for the severity of this drought and the accompanying heatwave? It can't. Our state climatologist has crunched the numbers, and what we are seeing is ... this was not the strongest La Niña ever recorded. But this was the most intense drought ever recorded here in West Texas. It was the most number of days over 100 degrees ever recorded at many weather stations across West Texas and around Texas as a whole. The state of Texas broke the record for the hottest summer ever recorded this sumer. ... So while La Niña was an instigator and a contributor to our current weather conditions, what we saw this summer was more than can be accounted for by La Niña alone. So the question is, what were the other causes? Like I just said, we know that climate change has altered the background conditions of our atmosphere, so we know that [there are] some contributions from climate change. There may be contributions from other natural factors as well. ... [Scientists] are going to be crunching the numbers to figure out exactly what the various contributions were to the very unusual summer that we had. ... It takes a lot of careful analysis and at least a year or two of research to figure out that answer.

TT: Is it possible that we could be experiencing this La Niña or potentially more La Niñas in general because of climate change? I mean, could climate change affect the arrival and disappearance of La Niña and El Niño?

Hayhoe: That's a really good question, and I think the answer is that it's very likely that climate change could interact with our natural cycles, because climate change is changing the background conditions of the atmosphere in which our natural cycles occur. So I think that there's every reason in the world to believe there could be interactions between climate change and El Niña and La Niña... 

Many of the strongest El Niños that we've seen over last 500 years or more have occurred over the last 50 years. So we are seeing stronger El Niño events. And I think this is borne out if you look at our rainfall records. We have seen some record rainfalls in El Niño events in recent years. We have also seen some bumper cotton crops in response to those El Niños. The La Niñas in recent years — we haven't seen too many record La Niñas. We've certainly seen record droughts, but we haven't seen record La Niñas. And the cycle tends to be shorter — in other words, we used to see five to 10 years in between El Niños. Now we're seeing two to three years in between El Niños and La Niñas ... so the cycle is happening faster than it used to. Whether this has anything to do with climate change or not — the jury is still very much out on that.

TT: Is it common for there to be back-to-back La Niña years as we seem to be experiencing now?

Hayhoe: Yes. This is very common to see a stronger La Niña followed by a weaker La Niña. It is a pattern that has occurred before. And that's one of the reasons why we believe it's going to happen again...

TT: How bad could this drought get? ... I mean, could we just be at the start of something even more awful than we've been experiencing?

Hayhoe: That again is the question I think we'd all like to know the answer to. Well, what we believe is likely is that La Niña next year will be weaker than this one. But here's the problem — last year was a very strong El Niño, so we started off with very wet conditions. ... Next year, even if we do get more rainfall than we got this year, the actual drought conditions could be worse because we don't have a reservoir of water in our soil to draw from. We're also running short on our surface water supplies, so our state climatologist, John Nielsen-Gammon, has said he believes the drought next year could be more severe than this year, simply because we are already starting in drought conditions. Because drought isn't just a rainfall deficit. Drought is a water shortage...

TT: I think you've [talked about climate change] with evangelical and conservative groups — what's been the reaction specifically here in Texas?

Hayhoe: In Texas, climate change is a hot-button issue. We hear a lot about it in the news, and what we hear is very confusing. One person says it's the worst disaster we've ever faced. Another person says it's not real, it's a problem people have made up to get funding. And a third person says, well, it's happening, it doesn't really matter, it's a good thing, it's not a big deal ... so what I've found... is that people in Texas are very curious about it ... they're a little bit skeptical. ... What I've found is if we take the time to talk about why we think the world is warming — what are the different lines of evidence for a warming world? How do we know it's not the sun or natural cycles or some other natural cause that's been driving the climate for years in the past? Why on earth do we think it's humans — small, tiny humans — that could be affecting something as large as the climate of our planet? Then if it is really happening, why should we care about things here in Texas?... And so what I've found is that [it's a good approach to] talk about these things, and ... go over the information and evidence that science has been collecting for hundreds of years ... and talk specifically about Texas.

TT: Where do you find these groups? Where do you talk to them?

Hayhoe: I talk to church groups, community groups, senior citizens homes — all kinds of groups. I talk to water managers, land managers, city officials, government officials, elementary schools, middle schools, university classes. I talk to just about as broad a range of people, because climate change matters to each of us. ... This is what I do in my free time. 

TT: Governor Perry has said, you know — there's manipulation of data, the jury is out or he's a skeptic about human-caused climate change. How does a climate scientist like you respond to that and how do statements like that from the governor impact your work?

Hayhoe: That's the message that we often hear. I was flying through Dallas-Fort Worth the other day, and CNN was on TV, and that's what somebody was saying on CNN. So it's no surprise that many of us think that it's not a real issue and that the jury is still out. The fact of the matter, though, [is] that the jury is not out on whether [the] climate is changing. The jury is also not out on whether humans have a contribution — whether humans are making a contribution to climate change. There's no question that natural factors are still affecting our climate today, just as they always have. But today, humans are becoming an increasingly important player in the game. So there should be a lot of debate about climate change, but where the debate should be is on what to do about it — what is the best way to address this issue while still managing a healthy economy, a healthy environment, and healthy lives for ourselves and our children.

TT: Do you think we should start working on [adaptation] and just kind of give up on climate change because we're way past say the 350 parts per million [mark]?

Hayhoe: No, I do not. I think we need to do both adaptation and mitigation. We have to adapt to what we can't avoid, but we also have the opportunity to reduce the impact that we are going to [have] on the world in the future. And we can do that in smart ways. The United States is the most wasteful country in the world in terms of how we use our energy. So by conserving our energy, first of all we would save money, and second of all we would reduce the impact we would have on our planet. So conservation is a win-win strategy. It's what our grandparents told us growing up — a stitch in time saves nine, turn off the lights when you leave the room. ... Another way we can contribute to that is to increase ... the efficiency of our cars, our lightbulbs, our appliances. 

TT: Are you and other climatologists just really scared?

Hayhoe: Well, that's a good question. ... What I think many of us don't realize, is that if we continue on our current pathway ... within our children's lifetime, they may be facing consequences that are dangerous. It will be difficult to maintain a robust economy and a good standard of life with these impacts. ... What I think concerns me the most is the fact that the further we go down this road of running through our natural resources like there's no tomorrow — the further we go down this road of doing exactly the opposite of what our grandparents told us — using up all of these finite resources and not conserving them, wasting them, taking pride in wasting them, rather than being smart and being efficient and saving our money, the further we go down this road, the greater the danger is of some potentially dangerous consequences. Some consequences that our science tells us are likely — killer heatwaves, prolonged droughts, massive floods. Even more frightening consequences that we don't see coming. 

TT: I wondered — is it difficult for you and your colleagues to work in Texas in any way? Texas is suing the government over GHG regulations. ... Does that affect your work? 

Hahoye: Being an optimist, I like to think of it this way — Texas is really the state of opportunity, and there are a lot of opportunities here. ... Texas is uniquely vulnerable to climate variability in terms of droughts and floods, as well as coastal storms. I know that I speak for my colleagues when I say that we live here. We love Texas. We would like to contribute our expertise to enhancing the welfare of this state. To making sure that we are planning a secure future for ourselves and for our children and for the citizens of Texas. So we would like to be able to offer our expertise to the state, but up to this point these opportunities have not been available.