NASA's James Hansen on Climate Change and Intergenerational Justice (Podcast)

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One of the most venerated scientists of our time, James Hansen is the head of NASA's Goddard Institute for Space Studies, a position he's held for three decades. Long before climate change was a household term, Hansen was one of the first to talk about its dangers. In recent years, Hansen has grown increasingly outspoken about the moral imperative to act, and has been arrested several times for demonstrating against issues like mountaintop removal. In our interview, Dr. Hansen talks about his support for nuclear power, his proposed carbon fee, the role of the climate contrarians, and plenty more.

Full text after the jump.TreeHugger: You wrote recently about a proposed pipeline for tar sand extracts, saying: "the phase out of emissions from coal is, itself, an enormous challenge. However, if the tar sands are thrown into the mix, it's essentially game over." What are tar sands and what makes this such a huge liability?

Hansen: The tar sands are the deposits, primarily in Canada, where there's oil mixed with sand. And you can extract the oil but it's a very energy-intensive process. So you end up emitting a lot more carbon dioxide than you would in a pure oil deposit. So it's not a very efficient way to get energy. But the basic point is that we know there's enough CO2 in the easily available oil and gas to take us up to the dangerous level of atmospheric CO2.

And what that means is that we can't afford to develop these unconventional fossil fuels. It just will push us far into the dangerous zone, and we will end up having to try to figure out how to get that CO2 back out of the atmosphere. So it just doesn't make sense to develop them to begin with.

TH: A lot of these metrics that we develop come from computer models. How should people treat the kind of info that comes from computer climate models?

Hansen: I think you would have to treat it with a great deal of skepticism. Because if computer models were in fact the principal basis for our concern, then you have to admit that there are still substantial uncertainties as to whether we have all the physics in there, and how accurate we have it. But, in fact, that's not the principal basis for our concern. It's the Earth's history-how the Earth responded in the past to changes in boundary conditions, such as atmospheric composition. Climate models are helpful in interpreting that data, but they're not the primary source of our understanding.

TH: Do you think that gets misinterpreted in the media?

Hansen: Oh, yeah, that's intentional. The contrarians, the deniers who prefer to continue business as usual, easily recognize that the computer models are our weak point. So they jump all over them and they try to make the people, the public, believe that that's the source of our knowledge. But, in fact, it's supplementary. It's not the basic source of knowledge. We know, for example, from looking at the Earth's history, that the last time the planet was two degrees Celsius warmer, sea level was 25 meters higher.

And we have a lot of different examples in the Earth's history of how climate has changed as the atmospheric composition has changed. So it's misleading to claim that the climate models are the primary basis of understanding.

TH: What are the most important benchmarks for people to know? Is it two degrees Celsius? Is it 350 parts per million?

Hansen: One of the other things that really tells us what's going on is the Earth's present energy imbalance. We know that the effect of adding CO2 and other greenhouse gases is to reduce the heat radiation to space-it acts like a blanket. And that means that there's more energy coming in from the sun than there is heat being radiated to space. And now, in the last 10 years, we've been able to measure that imbalance, because most of the excess energy has to go into the ocean. The atmosphere is very thin, it doesn't have much heat capacity. But the ocean is four kilometers deep, and it mixes, so it has a tremendous heat capacity.

And beginning about 10 years ago, different nations of the world distributed these Argo floats, more than 3,000 of them, around the world's oceans. They have an instrument package that yo-yos down to a depth of two kilometers, and then yo-yos back up.

And among other things, it measures the temperature in the ocean. What it tells us is that the ocean is gaining heat. It shows us that the planet is out of balance by about 0.6 watts per meter squared, averaged over the Earth.

And what that tells us is that there's more global warming, more climate change, that's in the pipeline. Because of this imbalance, the planet is going to continue to get warmer by at least half a degree Celsius additional to the 0.8 degrees Celsius that's already occurred. That's about twice as large if you put it in Fahrenheit.

So it's that kind of data which shows us that, in fact, the climate, the planet is responding as expected to these increases in atmospheric carbon dioxide.

TH: You've been critical in the past of climate change legislation and pushed for, essentially, a tax on carbon. What does that look like to you?

Hansen: Yeah. What the big banks and the fossil fuel industry have tried to influence is cap and trade with offsets, because that would allows business as usual to basically continue with only small perturbations. The problem is, it doesn't result in any significant reduction in the rate of emissions.

What we actually need is to put a price on carbon emissions so that will gradually increase over time. I call it a fee, because it should be collected from the fossil fuel company at the first sale, at the mine or the port of entry.

And the money that's collected should be distributed to the public. That way, the person who does a better than average job in limiting their carbon footprint, their fossil fuel use, would get more in this monthly dividend that would be deposited electronically in their bank account, or on their debit card if they don't have a bank account.

That fee on their fossil fuels would increase the cost of fossil fuels. And so energies that come from oil, gas, or coal, would become more expensive. But the person who's concerned about his budget would pay attention to that. And given the distribution of incomes and fossil fuel use today, 60 percent of the people would get more of a dividend than they'd pay in increased energy prices.

The wealthy person who travels around the world a lot on aircraft would pay more in those costs than they would get in their dividend. But this way, with the knowledge that this fee is going to continue to increase over time, the public and the business community would begin to make decisions that would move us toward increased energy efficiency and clean energies that don't produce carbon dioxide.

NASA's James Hansen on Climate Change and Intergenerational Justice (Podcast)
One of the most venerated scientists of our time, James Hansen is the head of NASA's Goddard Institute for Space Studies, a position he's held for three decades. Long before climate change was a household term, Hansen was one of the first to talk about

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