JIM LEHRER: And finally tonight, the new U.N. report on climate change, and to Jeffrey Brown.
JEFFREY BROWN: In Africa, between 75 and 250 million people could be competing for scarcer water supplies by 2020. In Asia, within several decades, heavily populated coastal areas will be at higher risk of flooding. And in North America, there could be less snow pack out west and longer, more intense heat waves in our cities.
Those were some of the scenarios outlined by the United Nations Intergovernmental Panel on Climate Change in a report issued this weekend. It was the fourth and final assessment of the group, made up of more than 2,500 scientists, that shared the Nobel Peace Prize last month, along with former Vice President Al Gore.
U.N. Secretary General Ban Ki-moon said the scientists had finished their work and now it was time for political leaders to act.
BAN KI-MOON, United Nations Secretary-General: Let us not point fingers or apportion blame. Rather, let us find common ground. Let us recognize that the effects of climate change affect us all.
JEFFREY BROWN: Today, British Prime Minister Gordon Brown was one of the first Western leaders to respond.
GORDON BROWN, Prime Minister of Britain: Our vision has one overriding aim: holding the rise in global temperatures to no more than two degrees centigrade. This requires global greenhouse gas emissions to peak within the next 10 to 15 years and to be cut at least by half by 2050. And it requires us to build a low carbon economy globally.
JEFFREY BROWN: World leaders will begin talks on a new international treaty to reduce greenhouse gas emissions when they meet in Bali next month.
Reasons for concern
JEFFREY BROWN: And for a closer look at the findings, we check back with Michael Oppenheimer, a member of the U.N. panel with whom we've been discussing these reports this year. He was part of the team of authors on earlier sections of the U.N. report. He's a professor of geosciences and international affairs at the Woodrow Wilson School at Princeton University.
MICHAEL OPPENHEIMER, Princeton University: Happy to be here.
JEFFREY BROWN: What does this final report do? What's the key thing in pulling together these -- synthesizing these various other reports?
MICHAEL OPPENHEIMER: This is the first comprehensive, soup-to-nuts examination of global warming in six years. And in it, the scientists point to five reasons for concern, areas where the impacts of global warming could be particularly troubling and particularly difficult to deal with, things like the loss of biodiversity, disappearing species; extremes of climate change, like heat waves or like cyclones, getting more intense; places where the economic impacts will hit hard in the next few decades; and then the cost to the world as a whole.
And, finally, things that are really big changes, like the loss of one of the parts of one of the major ice sheets in Greenland or Antarctica, leading to a very large sea level rise that would be extremely difficult to cope with.
Then, the report went on and pointed out that most of these changes come into play with a relatively modest warming, only two to five degrees Fahrenheit above today's level. And, finally, the report outlined what sorts of emissions reductions might have a chance of letting us avoid those kinds of impacts.
Rate of warming accelerating
JEFFREY BROWN: One thing that's clear here in the report is that the pace of warming is quickening.
MICHAEL OPPENHEIMER: Warming has accelerated in the last 20 years or so, and the sea level rise that results from the warming has likewise accelerated.
JEFFREY BROWN: So what's an example of a direct tie that you can see, in terms of an accelerating effect?
MICHAEL OPPENHEIMER: Well, the rate of sea level rise, for instance, if you look back a century, was something like four to eight inches. That rate has now increased by something like 50 percent in the last couple of decades. And that's due to the warming.
Temperature changes are happening more rapidly now. So, for instance, winter is, in some ways, becoming a thing of the past in parts of the world where they saw winters before.
These are things that people, the human being in the street, can detect themselves. And I think one of the reasons this problem is getting attention finally is not only the scientific consensus, but the sense among the average person that they're actually living the climate change.
JEFFREY BROWN: There is, in fact, in here a documentation of the amount of damage already done, right? I mean, that's part of what you're trying to show.
MICHAEL OPPENHEIMER: The world is already changing. The climate is changing. We are, whether we know it or not, subtly adjusting to those changes. And there's more to come. And as the climate change accelerates in the future, the question is, can we really adjust successfully to some of those reasons for concern?
The answer is: not if we let them get out of control. Really, there's a short window of opportunity. Maybe 10 or 15 years, as was said in the set-up piece, in which the world has a chance on get its act together, with first countries like the United States, developed countries reducing their emissions, and then the large, developing countries, like China, India, Brazil, following over the next 10 or 15 years.
If we don't do that, the chance of avoiding that two- to five-degrees Fahrenheit window, where the really strong impacts start to increase in risk, well, that window just shuts.
Rising sea levels
JEFFREY BROWN: And it is kind of striking to see the "if not by x year, then this." Give us some specific forecasts or examples that are in the report.
MICHAEL OPPENHEIMER: The chances of food shortages because of lack of water and reduced agricultural productivity in developing countries, particularly parts of sub-Sahara Africa, but really all over the low-latitude areas that are already semi-arid, increases if we get a warming just in excess of about two degrees Fahrenheit, and that's the kind of warming we could have over the next few decades.
The chances of parts of Greenland or parts of Antarctica disintegrating and going into the ocean and causing a sea level rise of anywhere from 20 feet to eventually perhaps as much of 40 feet, if both those chunks of ice go, the risks starts to increase with the warming of somewhere between one and four -- I'm sorry, two and four degrees Fahrenheit.
The drying of the southwest, we've had recent analysis which suggests that that's going to become a more or less permanent feature. And what's going to happen, with all the people moving still to the southwestern United States, if water becomes short in supply?
So these are things that are gradually working their way into our lives today, so we have episodes like the fires in California. I don't know if they had anything to do with global warming, but in the future that's the kind of episode we would expect more of.
JEFFREY BROWN: Now, we saw the secretary-general say that now it's time for political leaders. In the report, it says...
MICHAEL OPPENHEIMER: It was actually time for political leadership 10 or 15 years ago.
Reducing carbon emissions
JEFFREY BROWN: OK. In the report, it says, "A wide array of adaptation options is available, but more extensive adaptation than is currently occurring is required to reduce vulnerability to climate change."
Now, what does the report offer to politicians now? And we referred to this Bali conference coming up. What does the report offer, in terms of concrete measures that they should be looking at?
MICHAEL OPPENHEIMER: Well, adaptation means adjusting to climate changes that you can't avoid. The most important part of this report is to underscore that there are things that all governments, all individuals can do today to reduce the emissions of greenhouse gases.
All societies, particularly our own, need to get more efficient in their use of energy, need to switch to alternative energy sources, like renewable energy, solar energy, that are not dependent on the fossil fuels that produce carbon dioxide, the main human-made greenhouse gas.
And we've got to find a way in developing countries to stop them from cutting and burning their forests. Trees are made of carbon. It turns into carbon dioxide when it's burned, and it goes up in the atmosphere. Those are three general ways.
They come down to you in your life when you decide what car to buy, for instance. A car that gets high fuel economy emits less carbon dioxide. When you buy an appliance, an appliance that has high energy efficiency -- and it's right there in the Energy Star sticker on it, that appliance draws less electricity. Electricity in this country is mostly based on burning coal.
Those are measures that everyone can take to reduce their emissions.
JEFFREY BROWN: The report, though, stops short of setting those kinds of specific targets. Why is that?
MICHAEL OPPENHEIMER: The Intergovernmental Panel on Climate Change is allowed to frame the problem, but they are not allowed to make policy recommendations.
On the other hand, right here in Congress right now, there is legislation pending that would start the U.S. on the track of cutting emissions. So the U.S. Congress, hopefully, will look at this scientific report and say, "What does it mean, in terms of what we have to do?"
It doesn't take brain surgery. It doesn't take a brain surgeon to figure out the connections between the reasons for concern, the temperatures that come into play, and the emissions reductions that would be needed to avoid them. And that's the ballpark we're in. We have to get to those emissions reductions soon.
JEFFREY BROWN: All right. Michael Oppenheimer, thank you very much.
MICHAEL OPPENHEIMER: Glad to be here.