Selected category: Climate science

New Climate-Economic Thinking

By Gernot Wagner and Martin L. Weitzman

Each ton of carbon dioxide emitted into the atmosphere today causes about $40 worth of damages. So at least says standard economic thinking.

A lot goes into calculating that number. You might call it the mother of all benefit-cost analyses. It's bean-counting on a global scale, extending out decades and centuries. And it's a process that requires assumptions every step along the way.

The resulting $40 figure should be taken for what it is: the central case presented by the U.S. Government Interagency Working Group on Social Cost of Carbon when using its preferred 3% discount rate for all future climate damages. But it is by no means the full story.

Choose a different discount rate, get a different number. Yale economist Bill Nordhaus uses a discount rate of slightly above 4%. His resulting price is closer to $20 per ton of carbon dioxide. The Stern Review on the Economics of Climate Change uses 1.4%. The resulting price per ton is over $80.

And the discount rate is not the only assumption that makes this kind of a difference. In Climate Shock, we present the latest thinking on why and how we should worry about the right price for each ton of carbon dioxide, and other greenhouse gases, emitted into the atmosphere. There are so many uncertainties at every step—from economic projections to emissions, from emissions to concentrations, from concentrations to temperatures, and back to economics in form of climate damages—that pointing to one single, final number is false precision, misleading, or worse.

Of course, that does not mean that we shouldn't attempt to make this calculation in the first place. The alternative to calculating the cost of carbon is to use a big fat zero in government benefit-cost calculations. That's clearly wrong.

Most everything we know about what goes into calculating the $40 figure leads us to believe that $40 is the lower bound for sensible policy action. Most everything we know that is left out would push the number higher still, perhaps much higher.

It's not over 'til the fat tail zings

As just one example, zero in on the link between carbon concentrations in the atmosphere and eventual temperature outcomes. We know that increasing concentrations will not decrease global temperatures. Thank you, high school chemistry and physics. The lower bound for the temperature impact when carbon concentrations in the atmosphere double can be cut off at zero.

In fact, we are pretty sure it can be cut off at 1°C or above. Global average temperatures have already warmed by over 0.8°C, and we haven't even doubled carbon concentrations from preindustrial levels. Moreover, the temperature increases in this calculation should happen 'eventually'—over decades and centuries. Not now.

What's even more worrying is the upper tail of that temperature distribution. There's no similarly definitive cut-off for the worst-case scenario. In fact, our own calculations (based on an International Energy Agency (IEA) scenario that greenhouse gas concentrations will end up around 700 parts per million) suggest a greater-than-10% chance of eventual global average warming of 6°C or above.

Focus on the bottom row in this table. If you do, you are already ahead of others, most of whom focus on averages, here depicted as "median Δ°C" (eventual changes in global average surface temperatures). The median is what we would expect to exceed half the time, given particular greenhouse gas concentrations in the atmosphere. And it's bad enough.

But what really puts the "shock" into Climate Shock is the rapid increase in probabilities of eventual temperatures exceeding 6°C, the bottom row. While average temperatures go up steadily with rising concentrations, the chance of true extremes rises rapidly:

Climate Shock Table 3.1

That 6°C is an Earth-as-we-know-it-altering temperature increase. Think of it as a planetary fever. Normal body temperatures hover around 37°C. Anything above 38°C and you have a fever. Anything above 40°C is life-threatening.

Global average warming of 3°C wouldn't be unprecedented for the planet as a whole, in all of it geological history. For human society, it would be. And that's where we are heading at the moment—on average, already assuming some 'new policies' to come into play that aren't currently on the books.

It's the high-probability averages rather than low-probability extremes that drive the original $40 figure. Our table links greenhouse gas concentrations to worryingly high probability estimates for temperatures eventually exceeding 6°C, an outcome that clearly would be catastrophic for human society as we know it.

Instead of focusing on averages then, climate ought to be seen as a risk management problem. Some greenhouse gas concentration thresholds should simply not be crossed. The risks are too high.

This kind of focus on temperature extremes is far from accepted wisdom. We argue it ought to be.

Gernot Wagner and Martin L. Weitzman are co-authors of Climate Shock (Princeton University Press, 2015). First published by The Institute for New Economic Thinking.

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“Naomi Klein wants to stick it to the man. I want to stick it to CO2.″

By Jonathan Derbyshire, Prospect Magazine's The world of ideas.

Jonathan DerbyshireWhy is it so difficult to get people to worry about climate change? After all, the science is pretty unambiguous—pace the climate change “deniers”. Part of the problem, according to a new book, “Climate Shock,” by the economists Gernot Wagner and Martin L Weitzman, is that while what we know about global warming is bad enough, there are “unknown risks that may yet dwarf all else.”

Wagner, who is lead senior economist at the Environmental Defense Fund in the United States, visited London a couple of weeks ago. I caught up with him while he was here and talked to him about the difficulties of mobilising public opinion around the threats and challenges of climate change. 

GW: The big problem, frankly, is speaking the truth and talking about what scientists actually know and what they don’t know, which in many ways is even scarier. Saying the latest science out loud is [often taken to be] akin to catastrophising. That’s the big conundrum: on the one hand, “climate shock” shouldn’t be all that shocking—we’ve known this for quite a while. The problem is finding a way to state the scientific facts in a way that does not turn people off immediately.

JDSo it’s partly a public relations or political challenge then?

It’s more than that. Political, certainly. But it’s also a science communications challenge.

You mentioned scientific uncertainty just now. The book is, among other things, an attempt to deal with the challenge of climate change and the policymaking challenges from an economic perspective. But it’s also, it seems to me, a work of epistemology, almost—it’s a reflection on uncertainty and the implications that uncertainty has for policymaking.

Most books are written about what we know. This book is about what we don’t know. We clearly know enough to act. We’ve known enough to act for years, decades. Now, the more we find out, the more apparent it gets that what we don’t know is in fact potentially much, more worse. Choose you favourite analogy here—Nassim Nicholas Taleb’s “black swans,” Donald Rumsfeld’s “unknown unknowns”. That’s what it’s all about. The things we don’t know will most likely be the things that bite us in the back.

This is one of the things that makes climate change a public policy challenge unlike any other.

Climate change is uniquely long-term. It is uniquely global. It is uniquely irreversible and uniquely uncertain. You could probably identify other policy issues that combine two of those four factors, but none that I know of combines all four like climate change [does].

Continue reading in Prospect Magazine.

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Climate Shock in under 90 seconds

Think of the atmosphere as a giant bathtub. There’s a faucet—emissions from human activity—and a drain—the planet’s ability to absorb that pollution. For most of human civilization and hundreds of thousands of years before, the inflow and the outflow were in relative balance. Then humans started burning coal and turned on the faucet far beyond what the drain could handle. The levels of carbon in the atmosphere began to rise to levels last seen in the Pliocene, over three million years ago.

What to do? That’s the question John Sterman, an MIT professor, asked two hundred graduate students. More specifically, he asked what to do to stabilize concentrations of carbon dioxide in the atmosphere close to present levels. How far do we need to go in turning off the faucet in order to stabilize concentrations? Here’s what not to do: stabilizing the flow of carbon into the atmosphere today won’t stabilize the carbon already there at close to present levels. You’re still adding carbon. Just because the inflow remains steady year after year, doesn’t mean the amount already in the tub doesn’t go up. Inflow and outflow need to be in balance, and that won’t happen at current levels of carbon dioxide in the tub (currently at 400 ppm) unless the inflow goes down by a lot.

That seems like an obvious point. It also seems to get lost on the average MIT graduate student, and these students aren’t exactly 'average'. Still, over 80 percent of them in Sterman’s study seem to confuse the faucet with the tub. They confuse stabilizing the inflow with stabilizing the level.

Watch this video to avoid making the same mistake:

Excerpted from Climate Shock.

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We need a climate insurance policy – now

Q&A with Karin Rives first published on EDF Voices.

Climate Shock

Before climate change gets so bad that we may be forced to “geoengineer” ourselves out of catastrophe, a new book—Climate Shock—suggests that we reframe the problem altogether.

Gernot Wagner, a lead senior economist at Environmental Defense Fund and co-author of the book, says we ought to look at climate change as a risk management problem and treat it as such. I had a chat with Gernot about the book he will release next week together with Martin L. Weitzman, a professor of economics at Harvard University.

Karin Rives: Many books have already been published on climate change. What’s new or different about Climate Shock?

Most everyone focuses on what we know about climate change. Our book is about what we don’t know.

Call it Nassim Nicholas Taleb’s “Black Swan,” or the Rumsfeldian “unknown unknowns”—a state of complete and dangerous uncertainty and unpredictability. Call it what you want, but it’s that tail that may yet wag us in the end.

What we know is bad. What we don’t know is potentially much worse. Climate, in the end, is a risk management issue. Just like homeowners take out insurance against fires and flooding, society needs insurance against climate change.

KR: So what do we know?

Last time the planet experienced as much carbon in its atmosphere as there is now, sea levels where up to 66 feet higher than they are today. Camels lived in Canada. That was more than 3 million years ago. The geological clock read “Pliocene.”

We certainly know enough to take reasoned action today. And almost everything we don’t know points in one and only one direction: that action is all the more urgent.

KR: Why do we need to read this book now?

The time to buy our insurance policy is now—while we still can. And I’m speaking both metaphorically and literally.

Insurance here, of course, is to avoid dumping carbon into the atmosphere. We pay to have our trash picked up instead of just dumping it for free onto our streets. We similarly need to pay to avoid dumping carbon into our atmosphere.

That’s not free, but it’s still relatively cheap to do—and much cheaper than experiencing the consequences of unchecked global warming.

KR: What should be my three most important takeaways from your book?

Scream, cope, and profit.

We need to get the right policies in place, and soon. That’s “scream.” Then there’s some global warming we can no longer avoid—and that we are already experiencing. Let’s prepare ourselves better for that.

“Profit” is, of course, what you would expect two economists to say, dollar signs in their eyes and all. All that starts with smart investment decisions. Green, clean, and lean isn’t just got for the planet. It’s also the right financial choice and we need to ensure that it is much more so going forward.

The main takeaway, in the end, is that this isn’t some artificial battle between capitalism and the climate. It’s not about sticking it to the man. It’s about sticking it to carbon.

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"Risky Business" stands out in growing sea of climate reports

This blog post was co-authored by Gernot Wagner and first published on EDF Voices.

Put Republican Hank Paulson, Independent Mike Bloomberg, and Democrat Tom Steyer together, and out comes one of the more unusual – and unusually impactful – climate reports.

This year alone has seen a couple of IPCC tomes, an entry by the American Association for the Advancement of Science and the most recent U.S. National Climate Assessment.

The latest, Risky Business, stands apart for a number of reasons, and it’s timely with the nation debating proposed, first-ever limits on greenhouse gas emissions from nearly 500 power plants.

Tri-partisan coalition tackles climate change

The report is significant, first, because we have a tri-partisan group spanning George W. Bush’s treasury secretary Paulson, former mayor of New York Bloomberg, and environmentalist investor Steyer – all joining forces to get a message through.

That list of names alone should make one sit up and listen.

Last time a similar coalition came together was in the dog days of 2009, when Senators Lindsay Graham, Joe Lieberman, and John Kerry were drafting the to-date last viable (and ultimately unsuccessful) Senate climate bill.

Global warming is hitting home

Next, Risky Business is important because it shows how climate change is hitting home. No real surprise there for anyone paying attention to globally rising temperatures, but the full report goes into much more granular details than most, focusing on impacts at county, state and regional levels.

Risky Business employs the latest econometric techniques to come up with numbers that should surprise even the most hardened climate hawks and wake up those still untouched by reality. Crop yield losses, for example, could go as high as 50 to 70 percent (!) in some Midwestern and Southern states, absent agricultural adaptation.

The report is also replete with references to heat strokes, sky-rocketing electricity demand for air conditioning, and major losses from damages to properties up and down our ever-receding coast lines.

Not precisely uplifting material, yet this report does a better job than most in laying it all out.

Financial markets can teach us a climate lesson

Finally, and perhaps most significantly, Risky Business gets the framing exactly right: Climate change is replete with deep-seated risks and uncertainties.

In spite of all that we know about the science, there’s lots more that we don’t. And none of that means that climate change isn’t bad. As the report makes clear, what we don’t know could potentially be much worse.

Climate change, in the end, is all about risk management.

Few are better equipped to face up to that reality than the trio spearheading the effort; Paulson, Bloomberg and Steyer have made their careers (and fortunes) in the financial sector. In fact, as United States Treasury secretary between 2006 and 2009, Paulson was perhaps closest of anyone to the latest, global example of what happens when risks get ignored.

We cannot – must not – ignore risk when it comes to something as global as global warming. After all, for climate, much like for financial markets, it’s not over ‘til the fat tail zings.

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Reality check: Society pays for carbon pollution and that's no benefit

This open letter, co-authored by Gernot Wagner and first published on EDF Voices, was written in response to a New York Times article citing Dr. Roger Bezdek’s report on “The Social Costs of Carbon? No, The Social Benefits of Carbon.”

Dear Dr. Bezdek,

After seeing so many peer-reviewed studies documenting the costs of carbon pollution, it’s refreshing to encounter some out-of-the-box thinking to the contrary. You had us with your assertion that: “Even the most conservative estimates peg the social benefit of carbon-based fuels as 50 times greater than its supposed social cost.” We almost quit our jobs and joined the coal lobby. Who wouldn’t want to work so selflessly for the greater good?

Then we looked at the rest of your report. Your central argument seems to be: Cheap fuels emit carbon; cheap fuels are good; so, by the transitive property of Huh?!, carbon is good. Pithy arguments are fine, but circular ones aren’t.

First off, cheap fuels are good. Or more precisely, cheap and efficient energy services are good. (Energy efficiency, of course, is good, too. Inefficiency clearly isn’t.) Cheap energy services have done wonders for the United States and the world, and they are still doing so. No one here is anti-energy; we are against ruining our planet while we are at it.

The high cost of cheap energy

Yes, the sadly still dominant fuels—by far not all—emit carbon pollution. Coal emits the most. Which is why the cost to society is so staggering. Forget carbon for a moment. Mercury poisoning from U.S. power plants alone causes everything from heart attacks to asthma to inhibiting cognitive development in children. The latter alone is responsible forestimated costs of $1.3 billion per year by knocking off IQ points in kids. All told, coal costs America $330 to 500 billion per year.

Put differently, every ton of coal—like every barrel of oil—causes more in external damagesthan it adds value to GDP. The costs faced by those deciding how much fossil fuel to burn are much lower than the costs faced by society.

None of that means we shouldn’t burn any coal or oil. It simply means those who profit from producing these fuels shouldn’t get a free ride on the taxpayer. Conservative estimates indicate that carbon pollution costs society about $40 per ton. And yes, that’s a cost.

Socializing the costs is not an option

As someone with a Ph.D. in economics, Dr. Bezdek, you surely understand the difference between private benefits and social costs. No one would be burning any coal if there weren’t benefits to doing so. However, the “social benefits” you ascribe to coal are anything but; in reality they are private, in the best sense of the word.

If you are the one burning coal, you benefit. If you are the one using electricity produced by burning coal, you benefit, too. To be clear, these are benefits. No one disputes that. It’s how markets work.

But markets also fail in a very important way. The bystanders who are breathing the polluted air are paying dearly. The costs, if you will, are socialized. Society—all of us—pays for them. That includes those who seemingly benefit from burning coal in the first place.

Your claim that what you call “social benefits” of coal dwarf the costs is wrong in theory and practice. In theory, because they are private benefits. As a matter of practice because these (private) benefits are very much included in the calculations that give us the social costs of coal. What you call out as the social benefits of coal use are already captured by these calculations. They are part of economic output.

Our indicators for GDP do a pretty good job capturing all these private benefits of economic activity. Where they fail is with the social costs. Hence the need to calculate the social cost of carbon pollution in the first place.

So far so bad. Then there’s this:

Plants need carbon dioxide to grow, just not too much of it

In your report, you also discuss what you call the benefits of increases in agricultural yields from the well-known carbon dioxide fertilization effect. It may surprise you to hear that the models used to calculate the cost of carbon include that effect. It turns out, they, too, in part base it on outdated science that ought to be updated.

But their science still isn’t as old as yours. For some reason, you only chose to include papers on the fertilization effect published between 1902 and 1997 (save one that is tangentially related).

For an updated perspective, try one of the most comprehensive economic analysis to date, pointing to large aggregate losses. Or try this Science article, casting serious doubt on any claims that carbon dioxide fertilization could offset the impacts on agricultural yields from climate change.

Farmers and ranchers already have a lot to endure from the effects of climate change. There’s no need to make it worse with false, outdated promises.

Coal lobby speaks, industry no longer listens

It’s for all these reasons that, to borrow the apt title to the otherwise excellent New York Times story that ran your quote: “Industry Awakens to Threat of Climate Change”. And it’s precisely why the U.S. government calculates the social cost of carbon pollution. Yes, sadly, it’s a cost, not a benefit.

To our readers: Want to get involved? The White House has issued a formal call for public comments on the way the cost of carbon figure is calculated, open throughFebruary 26. You can help by reminding our leaders in Washington that we need strong, science-based climate policies.

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