UA, international climate researcher Overpeck on the new global climate change report

2014-04-06T20:59:00Z 2014-04-06T21:56:33Z UA, international climate researcher Overpeck on the new global climate change reportTony Davis Arizona Daily Star
April 06, 2014 8:59 pm  • 

Four top University of Arizona climate scientists spoke and answered questions on campus last week about the latest Intergovernmental Panel on Climate Change report, which was made public last Monday following a decent number of advance media leaks of its content. A fifth, UA Institute of the Environment Co-Director Jonathan Overpeck, a co-author of the IPCC report, gave a telephone presentation from New Mexico, where he was visiting family.

Here is a transcript of Overpeck's talk, which sums up the report's key messages, which include dire conclusions that climate change impacts are very real and will grow more severe over the coming decades if nothing is done to reduce fossil fuel use. Overpeck also pointed out that, more optimistically, we can do a great deal to adapt to these changes although there are limits to what adaptation can accomplish.

In future posts, we'll have a question and answer session featuring members of the 169-person audience, and some of the material from individual scientist presentations.

The other four panelists were Diana Liverman, co-director of the UA Institute of the Environment; Kathy Jacobs, director of UA’s Center for Climate Adaptation Science and Solutions; Christopher Scott, associate professor at UA’s Udall Center for Studies in Public Policy and the School of Geography and Development; and David Breshears, a professor at UA’s School of Natural Resources and the Environment.


I’m really sorry I’m not there in person; I have to be up here to help my folks thru another tough time. But it seems like I was just in Japan. I ended up working 36 hours straight through the night, on the final day, negotiating with policymakers from around the world and their delegations to finalize the summary for policymakers for this report.

I was also a lead author on the terrestrial ecosystems chapter, and I think you have a great panel here after I’m done to go thru some of the most important parts of this report. My job today is just to give you a little overview; and I just want to make it clear, a couple of the big things that came out of this.

 My sense is that this report definitely should come across as ‘We have a lot more confidence in what’s happening in climate system, what the impacts are, and what the potential consequences of continued emissions of greenhouse gas into the atmosphere will be, and of course remember that the primary cause of these emissions is burning of fossil fuels.’

So that’s one whole side of this story: if we don’t like these impacts, threats, risks that are outlined in this new report, we have a clear way to reduce them by reducing our burning of fossil fuels  and other activities that put greenhouse gases, primarily carbon dioxide, in the atmosphere.

 The report also did another thing though. It highlighted, in a much better way than ever before, adaptation options that are already being employed around the world to deal with the ongoing climate change, the ongoing impacts of climate change which are growing around the world. And I think that makes this report a little bit more upbeat than before. And of course, in the news from what I’ve seen, everyone’s focused on the downside, all on the impacts, some of them quite potentially disastrous for humans and the natural system,  and those are very real. But at the same time, people around the world  are getting their act together particularly places like the University of Arizona, to figure out, how do we manage the problem.

And that’s another innovation in this report we really tried to frame things in terms of risk. And we did that in part because there’s sort of a strong basis in society, particularly in businesses and government, for risk management. It’s not something that’s alien to most people in the world, but it’s something they’re learning how to  do better and better with time. That’s why if you read this report, you’ll hear a lot of about risk rather than just impacts, threats and other terms. Another thing that has come up in the media coverage and it’s very real is that this report is a conservative report. And of course you have some of climate skeptic organizations that are well prepared to try and dilute the message coming out of this report, that this an alarmist report. And I can tell you it’s far from alarmist. If we wanted to be alarmist, we could report not just on consensus of what happening but start to focus on some of the things that are much less well known that are even scarier.

So looking at that, I think there are a couple of things that I would take home. One is that adaptation—we can go on to do a better job here -- but we also are real clear that if we don’t do something about climate change, don’t slow it significantly, we’ll start to hit some of the limits of adaptation.

 A good example of that might be sea level rise which is clearly ongoing and is accelerating. Sea level rise will literally flood some countries out of existence. If you are in those countries or on the coastline, you can adapt, and it will be extremely expensive to deal with the rising sea level. You can move infrastructure inland, you can figure out ways to deal with salt water intrustion into your water supply, you can move large populations of people. It will be costly. But in the end there will be some places in the world, increasingly more and more, too, that literally can’t adapt any further and large tracts of land will be lost to sea level rise.

We also highlighted in this report as never before the impacts of high end climate change. In the past, I think the scientists and policymakers were fairly confident we’d have this situation under control by now but since we don’t, as humankind, we are starting to articulate what happens if we really let it rip, and let it get out of control. And some of those stories are in this report. They are not just stories, they are real, tangible risks, like sea level rise.

Another one that we covered in our chapter and confirmed in previous reports is that there is a very real risk that climate change will create a major extinction event for a large fraction of terrestrial and fresh water species during this century and beyond if we don’t curb the climate change. And this is made particularly bad by a lot of other stresses on vegetation and animals that now exist.

And Dave Breshears can talk more about that. Another thing Dave can talk about, we highlighted in our report, which is very close to his research as we are citing a lot of his work, is that we now are seeing an unusual amount of tree death and forest dieback around the earth in many places due to unusually hot and dry conditions. So if you talk about hot and dry, you know that’s got to have an element of climate change.

Lastly, bringing it close to home, another thing that’s really important to me is keeping an eye on messaging in IPCC reports and elsewhere about our own drying out and warming up in the Southwest. We are warming up, drying up. We are warming faster than any part of the United States, and we’re clearly drying out. We’re in a drought. Something that is clear . . . maybe not clear enough, but is clear in this report this drying and particularly the warming which we know is due to humans, is causing reductions in spring snowpack and runoff, up in our headwaters, and that is causing our water supply to grow smaller and smaller with time. So for us in Arizona, the rest of the Southwest, California . . . one thing, the best thing we can do about water supply is curb climate change because it certainly adds a big impact as it warms up and melts the snow.

So the bottom line in all of this is that this report really shows that emission of greenhouse gases from the burning of fossil fuels is already having major impacts around the world. Fortunately people around the world, and scientists helping, are coming up with ways of dealing with those impacts but they are growing and they’re growing in the United States and if climate change is left unchecked, many of the impacts will exceed our ability to adapt. And that’s why we have to be very clear that the ultimate solutions are gonna include both adaptation to the climate change that’s already underway and can’t be stopped but also mitigation, or reducing those greenhouse gas emissions. Otherwise we are going to have a very different world 100 years from now . . .

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About this blog

Star reporter Tony Davis covers topics in this blog that you have read under his byline for more than 30 years in the Southwest: water, growth, sprawl, pollution, climate change, endangered species, mining, grazing and traffic.

To reach Tony call 806-7746 (office) or 349-0350 (cell) or write him at

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