Climate Change

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What does climate change mean for Arizona? A new report details that. Hear from ASU researcher Nancy Grimm.

TED SIMONS: A recently released also report on climate change suggests that Arizona could be in for some rough weather. Talks about hotter temperatures, more severe storms, and deeper droughts. Nancy Grimm, an Arizona State University ecologist, helped prepare the report and is here to talk about it. Thank you so much for joining us on "Horizon."

NANCY GRIMM: Thank you. It's good to be here.

TED SIMONS: The federal study White House report. What was your part in this report?

NANCY GRIMM: Well, the report is written by a team of authors and all the authors essentially have to approve all parts of the report but my particular role was that I played a part in a few of the sections of the report, including the section on society, the section on the southwest, and the section on water.

TED SIMONS: Ok. Let's talk about the southwest and how we are already being affected by climate change.

NANCY GRIMM: Well, the southwest is actually one of the regions that has seen the most climate change so far, the most warming I should say. The greatest amount of temperature increases. And what we are expecting to see in the southwest is an increased -- decreased frequency of precipitation or amounts of precipitation in the winter, of course our water supplies are coming from the snow pack in the Colorado, rocky mountains, and so that is already decreasing and we're expecting to see a decrease in the amount of runoff coming that provides our water supply here in the Phoenix area.

TED SIMONS: Now, as far as Arizona's concerned, I know the early snow melt is a factor as well. What else do we look at and what other signals are there? Because some folks are wondering is this not just the natural cycle of the earth going through different climactic periods. You're saying it's here, getting worse, worse than even we originally thought?

NANCY GRIMM: The report is very clear on that. While it's true there are climate cycles, they're on kind of recurrence intervals of 100,000 years or so, and what we're talking about is very rapid climate change, in the -- in industrial times. That is very clearly attributable to rising greenhouse gases in the atmosphere that are caused by human activities. And the report states very clearly that climate change is here now. It's with us now. And it is likely to continue. The models all project that it is -- that there's a certain amount of climate change that is already locked in, regardless of what we do, so there's a certain amount of warming and changes in the hydrologic cycle that we have to come to expect and we need to be thinking about as a society, what we can do to prepare for that.

TED SIMONS: As far as the droughts here in the southwest, are we talking longer droughts? Are we talking deeper droughts? Are there going to be more spikes in terms of droughts? Worsening drought means what?

NANCY GRIMM: It's harder with water to make projections and the models are less certain when it comes to the hydrologic cycle and this is particularly true for the southwest because as you know we have -- we can have very wet year as we had in 2008, 2005, we can have an extremely dry year, and so that's the natural variability that we have to detect a change again. The models are projecting that there could be more severe drought that is, long term droughts that really are reducing the amount of water available in this region.

TED SIMONS: Ok. And with that you've got everything from what, insect infestation to wildfire concerns?

NANCY GRIMMl: Yeah. As you know in a dry year we often have a lot of fire warnings around here and that's partly a consequence of for the southwest a very interesting story of the interaction of different factors that humans have influenced one of them is climate. We're talking about here. But also invasive species, or exotic species that are brought in that don't belong in the Sonoran desert. Two common ones are red broom around here and southern Arizona more common is the buffle grass. These species can really take off during a wet spring and then they build up quite a lot of fuel and the Sonoran desert is not an ecosystem that has really adapted to fire or has persisted in the presence of fire, and so this is a concern that if fire frequency increases as a consequence of hotter temperatures, drier soils and more of these introduced grasses, that we could see some of the characteristic species of Sonoran desert like Saguaros and Palo Verde trees disappearing.

TED SIMONS: We're seeing a little in the high country with Ponderosa and bark beetle infestation up there.

NANCY GRIMM: Yes, another example, because the bark beetle weakens trees and then they're more susceptible to drought and then when they die they are feeding fires so there's an interaction there of fire, drought, and this bark beetle.

TED SIMONS: I know you're not a sociologist, but from where you sit and all the research, there still seems to be allowed, if not widespread contingent of folks who think there is no such thing as manmade global warming. How do you respond to those folks?

NANCY GRIMM: Well, I haven't had to respond to them directly except from the report. We actually had quite a few comments from the public comments that came from these folks. And I guess I don't really know why so many people are so vocal about this. It seems that the evidence is quite clear, there's a very clear logical chain associated with human activities causing increases in C.O.2. We've known for 150 years that C.O.2 warms the earth more than it would in the atmosphere and so more of it is going to warm the earth more. What we have in this report is essentially every agency of the federal government that's associated with climate change in any way, with climate research in any way, approving the report, contributing as authors, and it synthesizes for the first time in probably a decade all of the known research, all of the best science about changes in climate, showing that those changes are here now and that they're projected to continue.

TED SIMONS: And we talked earlier, you said that the irony of all of this is that some areas of the country that could be or may very well be affected most are some of the nicest spots that we all like to go to.

NANCY GRIMM: Yeah, this is one of the things we reported on in the report. We summarized in the report, let's just take the southwest. This is a great example, because here we have a very desirable place to live. People want to live here because the climate's wonderful and so they're moving here in droves and we are consistently trading places with Las Vegas as the fastest growing metropolitan region in the country. People want to move here and so what you have is a sort of collision of rapid urbanization, increased demand for already precious water supplies and the specter of climate change with reduction in those water supplies, and this is one of the places where people want to live that's putting them most at risk of the effects of climate change. Another example would be the coast, which are expected to see increase in rising sea levels.

TED SIMONS: All right. Well, it's fascinating stuff. Thank you so much for joining us and telling us more about the report.

NANCY GRIMM: Thank you.

Nancy Grimm:ASU researcher;

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