Climate 411

Statistics 101: Climate policy = risk management

By / Bio / Published: September 10, 2015

Bjørn Lomborg reviewed my book, Climate Shock (Princeton University Press, 2015), joint with Harvard’s Martin L. Weitzman, for Barron’s over the weekend. He started it by stating that “global warming is real.”

So far, so good.

But the book is not about whether the climate is changing. It is.

The book is about whether we are getting the order of magnitude of its effects right. Weitzman and I argue forcefully — in prose in the text, supported by a significant amount of research going into the 100-page end notes — that it’s what we don’t know that really puts the “shock” into Climate Shock. Lomborg asks how we can know that, if apparently we don’t.

The answer is simple, and it’s a statistical point that can’t possibly be lost on Lomborg, a former lecturer on statistics. The set of distributions that most directly represent climate uncertainty — the link between concentrations of carbon dioxide and eventual temperature outcomes — is inherently skewed. We know, and Lomborg agrees, that adding carbon dioxide increases temperatures. (Back to 19th century science.)

So we can very clearly cut off the distribution linking a doubling of pre-industrial concentrations to temperatures at zero. In fact, we can cut it off at least at around 1 degree Celsius (almost 2 degrees Fahrenheit). The world, after all, has already warmed by over 0.8 degrees Celsius (around 1.5 degrees Fahrenheit), and we haven’t yet increased pre-industrial concentrations by even 50 percent.

Reprinted from Climate Shock, with permission from Princeton University Press

Reprinted from Climate Shock, with permission from Princeton University Press

That skewedness of the underlying distribution is real. It’s important. The correct response, then, to those who are too sure about where the climate system will go isn’t to say, “cool it.” It’s to take the uncertainties seriously. Those, sadly, are skewed in one direction.

Climate risk is not our friend. It ought to prompt us to rethink not just how we talk about climate change. It should also inform our response. The burden of proof clearly rests on those who argue against these statistical facts.

Posted in Greenhouse Gas Emissions, News / Read 4 Responses

New Climate-Economic Thinking

By / Bio / Published: April 23, 2015

By Gernot Wagner and Martin 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.

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:

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). This post was originally published by The Institute for New Economic Thinking.

Posted in Economics, Energy, Greenhouse Gas Emissions / Comments are closed

Traveling to the climate march: Worth the carbon footprint?

By / Bio / Published: September 18, 2014

(This blog originally appeared on EDF Voices)

Lauren Frohne/Flickr

Looks like the simmering “climate swerve” may come to a boil on September 21 in New York City for what’s billed as the People’s Climate March.

Bill McKibben called for it in the Rolling Stone magazine. Tens of thousands are slated to respond to his call, ostensibly to channel Franklin D. Roosevelt’s ghost and make world leaders “do it” – push for strong climate policies, now.

Except that it wouldn’t be the climate movement if it weren’t beset with self-doubt and second-guessing. Going to New York, you see, produces carbon dioxide emissions, the very cause of the problem. So how then can climate activists justify riding, driving or – heaven forbid – flying in the name of climate action?

We do because traveling to Manhattan, and expanding our carbon footprint in the process, may be better for the planet in the long-run than if we stayed home.

Real climate policy is what we need

Every cross-country roundtrip flight causes about a ton of carbon dioxide, per passenger. Driving emits carbon, if not quite as much. Trains do, too. Even if you bike or walk, you will need extra calories, which also come with additional carbon emissions.

A plethora of online calculators can help you decide how to minimize your own footprint. You could get positively crazy making these calculations, and some possibly have.

If you spend so much time online researching your carbon footprint that your power consumption shoots up, you may be on the wrong track.

We should all be decreasing our carbon footprint. The emphasis is on “all.” Real climate action, then, must go far beyond individual action by the committed core.

The People’s Climate March will take place on the eve of the United Nations’ Climate Summit, convened by Secretary General Ban Ki-moon on September 23, and for good reason. It’s policy that needs to change.

Coal cannot be banned, but it can be priced

The headwinds are strong, to say the least.

King Edward I banned the burning of coal in 1306, replete with the death penalty for repeat offenders. It didn’t take long for the ban to be lifted, and the coal-fueled industrial revolution has brought untold riches to many.

The coal question, in many ways, goes to the heart of the matter. Banning coal is out. It is neither possible nor necessarily desirable.

What we need is to incorporate the full societal cost of burning that coal into everyone’s private decisions.

At the moment, each ton of coal and each barrel of oil used causes more in external damage to human health and the environment than it adds in value to the economy. That doesn’t mean we should not burn any coal or any oil, but it does mean putting a price on carbon, ideally directly via carbon markets or taxes.

It means regulation. It means standards. It means tax reform. It means taking significant policy steps to restructure misguided market forces so they lead us off of the current high-carbon, low-efficiency path.

Composting counts, but it’s not enough

Going green is fine. I don’t drive, don’t eat meat, and do all sorts of other things that minimize my own carbon footprint. The climate movement is home to quite a few who go the full-on vegan, composting, skip-coffee-because-it’s-bad-for-the-climate route.

But going green is only good if it actually gets somewhere.

If you compel your in-laws to compost more and drive less – go forth and proselytize. But if this makes them ignore efforts to achieve critical policy changes, your campaign for a voluntary green lifestyle should probably stop.

Many actions needed for a climate revolution are akin to a bootstrapping problem. Building a wind turbine takes steel, which in turn takes energy. The green energy revolution then may well mean an increase in current, largely fossil-fueled energy use for the sake of decreased carbon emissions later.

The Climate March falls into the same category. Going to New York implies emissions, as do most other things we hold near and dear in our daily lives.

Participating in the march won’t change that fact overnight. But calling for real, measured climate action just might. Helping to build the momentum toward policy change is precisely what’s needed.

If you can do it while also decreasing your own footprint, so much the better. If not, choose policy change.

Bike if you can, fly if you must. By all means, go to New York on September 21.

Posted in Greenhouse Gas Emissions, News, Policy / Comments are closed

“Risky Business” stands out in growing sea of climate reports

By / Bio / Published: June 26, 2014
Receding beach on North Carolina’s Outer Banks. Source: FEMA/Tim Burkitt

(This blog originally appeared on EDF Voices)

This blog post was co-authored by Jonathan Camuzeaux.

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.

Posted in Basic Science of Global Warming, Cars and Pollution, Economics, Extreme Weather, Greenhouse Gas Emissions, Health, Jobs, News, Policy / Read 1 Response

When it comes to carbon, pay now or pay more later

By / Bio / Published: April 17, 2014

(This post originally appeared on ensia.com) 

Economics is largely just organized common sense, and it doesn’t get much more common sense than benefit-cost analysis. Want to decide whether to buy that apple, make that investment or pass that clean air rule? Tally up the benefits. Tally up the costs. If benefits outweigh costs, do it.

Although in many ways climate change is a problem in its own league, the same principles apply. Secretary of State John Kerry recently said, “The costs of inaction are catastrophic,” and they most likely would be. While climate change ought to be a risk management problem — an existential risk management problem on a planetary scale — that realization alone may not always be good enough. Despite the inherent risks and uncertainties, sometimes we need a specific number that we can plug into a benefit-cost analysis.

The U.S. government makes lots of regulatory decisions that have important implications for the climate. Any benefit-cost analysis of these decisions ought to include their climate impact. If a particular decision will lead to more greenhouse gas emissions — building the Keystone XL pipeline, for example — that figure ought to go on the cost side of the ledger. If the decision will lead to fewer greenhouse gas emissions — such as carbon pollution standards for power plants — that figure adds to the benefits side.

Such benefit-cost analyses require a dollar figure for the social cost of carbon pollution. The best we currently have is around $40 for each ton of carbon dioxide emitted, calculated by averaging results from the three of the most prominent and well-established climate-economic models. Uncertainties around the $40 value notwithstanding, putting in $0 is not an option. That, sadly, is what some with clear stakes in the outcome are arguing, however weak the ground they stand on.

In fact, $40 is very likely on the low end of the true cost of CO2. By definition, it only includes what is known and currently quantifiable. It doesn’t include many things we know are linked to a changing climate that aren’t so easily quantified, such as respiratory illness from increased ozone pollution, the costs of oceans turning ever more acidic and impacts on labor productivity from extreme heat. If these were factored in, the $40 figure would certainly be higher.

And the list of what’s missing in the current calculation goes on, as a recent commentary in Nature points out. For example, the models used to calculate the $40 figure are based on costs associated with higher average temperatures rather than costs of increased weather extremes. Taking extreme events seriously in the social cost calculation would increase the $40 figure further still.

We know climate change is and will be costly. How costly exactly is up for discussion, but it’s clear that we should at the very least use the $40 per ton figure in any benefit-cost analysis that involves climate impacts. That’s common sense, too.

Posted in Clean Power Plan, Economics, Greenhouse Gas Emissions, Policy / Read 1 Response

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

By / Bio / Published: February 4, 2014

This open letter, co-authored by Jeremy Proville 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 for estimated 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 damages than 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.

Posted in Economics, Greenhouse Gas Emissions, Science, Setting the Facts Straight / Read 1 Response