The Technology Challenge: An Interview with Physicist Marty Hoffert

March 31, 2008 |

Marty Hoffert is Professor Emeritus of Physics and former Chair of the Department of Applied Science at New York University. He wrote the landmark 2002 article in the journal Science that concluded global warming was a energy technology problem, not a regulation problem, which inspired Michael Shellenberger and Ted Nordhaus to start working on a new Apollo project. In this interview, he makes the case for why the six-wedge scenario to climate stabilization is wrong -- we actually need 18 wedges.


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You've been working in the field of clean energy for much of your adult life. If this was on our country's radar back in the sixties and seventies, why don't we have viable solutions by now?

We had a brief Camelot with Jimmy Carter and his national energy policy. There was funding for this research, and we thought we were going to convert the system of energy based on fossil fuels to one based on renewable energy. We even built a wind turbine on the roof of our building; it was very exciting. Until the catastrophe of 1980: the election of Ronald Reagan.

One of the first things he did was to rip the solar panels off the roof of the White House. The funding disappeared for a lot of the projects we had started. The attitude of the Reagan government was that it wasn't their job to develop alternative energy technology -- that it should be done by the marketplace. The problem was that none of our alternative energy ideas were cost effective compared to fossil fuels. Our society was lulled into a stupor. OPEC made oil prices go up but not up high enough to make anyone change their oil consumption.

You've worked with James Hansen, one of the first scientists to warn about human-caused climate change.

Yes, he's become very controversial, as have I, as have many of my colleagues. We didn't see climate change as a social science problem or a political problem; we saw it as a basic climate problem. The challenge was how to fuel our civilization without fossil fuels.

You wrote a landmark 2002 piece for Science arguing for advanced energy technologies through a new Apollo Project. Princeton professors Socolow and Pacala responded with a piece that argued that we have basically all the technology we need. What's the nature of the disagreement?

For one thing, the scientific disagreement between Rob Socolow and myself is more apparent than real, though the two of us may be the only ones on the planet who understand that. Rob has two different stories about the ability of existing technology to supply enough "wedges" of carbon emission reductions to maintain emissions constant for fifty years: One for the public at large (who might not be able to take the truth in his view) and another for scientists who understand the nitty-gritty of "wedges."

I stipulate that holding carbon emissions roughly constant for fifty years might be enough to keep atmospheric carbon dioxide below 450 ppm, perhaps enough to stave off global warming above two degrees Celsius, which many climatologists fear could trigger irreversible glacial melting. The problem with the formulation of Pacala and Socolow in their Science paper, and the later paper by Socolow in Scientific American issue that you cite, is that they both indicate that seven "wedges" of carbon emission reducing energy technology (or behavior) -- each of which creates a growing decline in carbon emissions relative to a baseline scenario equal to 25 billion tonnes less carbon over fifty years -- is enough to hold emissions constant over that period.

That is incorrect.

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Credit: Dr. Martin Hoffert, Scientific American, September 2006

In essence, Socolow is implying that we have all the technology we need to deal with climate change?

A table is presented in the wedge papers of 15 "existing technology" wedges, leading virtually all readers to conclude the carbon and climate problem is soluble with near-term technology; and so, by implication, a major ramp-up of research and development investments in alternate energy technology like the "Apollo-like" R&D Program that we call for, is unnecessary.

How many wedges did you find would be necessary in your research?

The actual number of wedges to hold carbon dioxide below 450 ppm is about 18, not 7, for Pacala-Socolow scenario assumptions, as Rob well knows; in which case we're much further from having the technology we need. The problem is actually much worse than that, since the number of emission-reducing wedges needed to avoid greater than two degree Celsius warming explodes after the mid-century mark if world GDP continues to grow three percent per year under a business-as-usual scenario.

Most ominous is that the US, China and India are building the wrong energy infrastructure for the second half of the 21st century with their 900 new conventional coal electric power plants. We must stop this. But policy makers can have no inkling how dangerous these plants will be if they're lulled into a false sense of security by those seven wedges. Rob says he supports research funding to develop a carbon-neutral energy system worldwide, but when we gave him the chance to sign our recent letter to Congress and presidential aspirants calling for an Apollo-like program with that objective, he reluctantly declined.

But didn't you say that Socolow "well knows" that we need more wedges than initially anticipated?

A tree falling in the wilderness that no one sees might as well not have fallen. A paper by Socolow presented at a meeting at Exeter, UK, acknowledged, albeit in a footnote on page 350, that the total number of wedges needed to keep carbon dioxide emissions constant for fifty years is 18, not 7.

If Socolow agrees with you about the 18 wedges, why would he lead the public to believe otherwise?

When you read this obscure paper you'll see that Rob calls the extra 11 wedges "virtual." They're assumed in his business-as-usual to be produced "spontaneously;" that is, without any specific policy intervention like the stepped up research and development we propose. These wedges, which aren't explicit, could easily contain the same existing energy technologies as those assigned to the seven explicit wedges. In fact they're more likely if they happen to be based on existing tech since they don't need policy incentives to make them so.

In any case, double counting technologies is likely, and what's more important, even their 15 tabulated wedges aren't enough to hold carbon dioxide emissions constant, which pretty much destroys their conclusion that existing technology is enough. How many people know this? (I suspect that by this time, Al Gore does.)

What do Pacala and Socolow say about "decarbonization," the idea energy use will rely less and less on carbon over time?

Pacala-Socolow's baseline emission scenario growing at 1.5 percent per year assumes a continuation of the historical "decarbonization" trend of the carbon to energy ratio in the fossil fuel mix from gas to oil to coal, each of which has a lower carbon emissions per unit of energy.

This trend has now reversed, as the world switches to coal because of gas and oil production peaking, as energy demand keeps rising driven by the economic growth of China and India. The result is that carbon emissions are now growing at three percent per year, not 1.5 percent per year, leading us to even more wedges.

You've now done graduate work in sociology in economics, in addition to your extensive science and engineering training. With your social sciences background, don't you see climate change as a policy problem as well?

I put myself more at the geek end of the geeks versus wonks spectrum. Even though I studied social science, I look at the problem primarily as a technological problem. Although I know the social problem is very hard, if we can't solve the technological problem, we'll never solve global warming.

It's really both, but the problem is that the people who can do the engineering and the science can understand the social science, while the reverse isn't true. We're living in a country that is increasingly tech illiterate, and that includes many decision makers.

There's a grassroots movement under way for a Scientific Presidential Debate. How important is it that the president be well versed in matters of science? How much should a president know?

Anyone running for president should know about these very elementary things. I'm not confident that any of the candidates are actually aware of this. I'd love to see a debate but it would have to be based on having the most basic understanding of how this stuff works. I've briefed people in Congress on this stuff, and I know that many of them are quite shaky.

Do you have any ideas about how we might get better-informed leadership?

I think the Secretary of Energy position should be upgraded to be comparable to that of Secretary of State and Secretary of Defense, and somebody like Gore or Clinton should be appointed to it. And we have to start implementing some of the ideas that Gore has already called for, like a moratorium on building more coal plants.

Talking about a moratorium on new coal plants is a huge challenge here in the U.S. But look at China -- they are building a new coal plant every week. It doesn't make much sense to talk about coal without factoring China into the equation.

The only thing we can do is to try to offer them an alternative, and right now we don't have one. We don't have anything cost effective. We've lost a quarter century since the Regan administration took office. If we had continued Carter's administration -- although it was certainly wasteful -- we might be in a better position now.

How feasible is space solar power? What role can it play in the solution?

I think it's a promising source of energy, but not the first thing we should do. In the long term, we need solar energy or nuclear fusion, because we're going to use up all the fossil fuels. The problem with solar is how to match supply and demand - that requires transmission and storage on massive scale by technologies that we don't really have. One way to solve that is to collect sunlight in space, where the sun shines 24 hours a day, and beam it to earth. But we're not putting any money into that technology. We're doing a lot of things that are very near term solutions, but in long term they are not going to be effective.

What about high altitude wind that Google is pushing now?

We should be looking into it, but there are a lot of things we should be looking into: more efficient homes, automobiles powered by renewable energy, aircrafts, a whole spectrum of innovations, some of them only able to work if we have an infrastructure designed for them. That's where the federal government has to come in.

Have you been following the evolution of the Lieberman Warner climate bill? How do you feel about the prospect of setting up a cap and trade scheme in the US?

I think it's a distraction. Cap and trade won't force the changes that we need fast enough. We have to directly vest in R&D to get the kind of energy systems we need. Cap and trade is an indirect way of doing it.

There are various ways of paying for the changes we need but getting money is the least important thing. We have plenty of money. We only spend three billion dollars on energy a year -- we should go up to at least $30 billion. I don't think the problem is money at all; I think the problem is bad leadership, scientific illiteracy, and a lack of understanding of the choices. We need a revolutionary change in world energy systems now and anything that doesn't get us directly towards that is a distraction.

Why is the environmental community so focused on cap and trade if the main solution should be government investment in technology?

In my opinion, emission regulating policy options like "Cap and Trade" are motivated mainly by market economists, who hold a Marxist-like command and control policies to simply cap emissions are ideologically anathema. The idea is to cap total emissions and at the same time create a market in which the "ability to pollute" is embodied in tradable emission permits. A market permits trading, or gambling on the outcome. The possibility of windfall profits trading in emission permits is why Enron lobbied the Bush administration to sign Kyoto Protocol -- Enron being a flagship company for believing that energy isn't a problem for creative engineering, but a problem for creative accounting.

Emission trading had some success in the US to control acid rain from sulfur emissions, but this isn't a good analog because in that case the technology existed to remove SO2, a pollutant that's a small percent of stack gases. Carbon dioxide isn't a pollutant in that sense. Carbon dioxide gas is inherently produced by any fossil fuel combustion process a hundred times more plentifully than a pollutant like sulfur dioxide; and we have no technology on the shelf remotely capable of limiting these carbon emissions cost-effectively, as we need to. Which is why we need to create these technologies.

How much time do you think we have to solve this problem?

We have no time to solve this problem. The question isn't how much time we have; the question is how bad it's going to be, and whether our civilization will be able to survive it. Some people think it's already too late. That's what we have to fight against -- that we'll go from believing this isn't really a problem to believing it's a problem to great to do anything about. I think we have a chance to do it and I think we should be fighting for it. The way to do it is to get real about changing basis of our society in terms of energy.

Your son Eric is a computer scientist. Does your work ever overlap?

Eric and I have a consulting company together. He has a lot of friends in Silicon Valley, and we've done some studies for those people about clean energy technology.

This is a multi-generational problem; it's going to take a hundred years to solve it. I'm trying to get my granddaughter involved too -- she's very smart. We need more women going into science and engineering in this country because we're missing out on some great minds.


As an American from the West Coast who lived in Australia for six months, I can attest to the serious and prolonged burrito drought ravaging the entirety of the continent! Anyone with the gumption to start a burrito chain in Oz could make some good money...

Great profile of a great BTGen fellow. Leigh is missed around here.

By Jesse Jenkins on 2010 04 01

I must agree with Professor Hoffert on tech illiteracy. I have found in many discussions on the carbon issue that many folks have a hard time dealing with the quantitative side of the issue. The technology piece is as important as the policy questions.

By R Margolis on 2008 04 02