Author Archives: Gernot Wagner

Is energy efficiency a good thing even with rebound?

By Inês Azevedo, Kenneth Gillingham, David Rapson, and Gernot Wagner.

Lighting is critical to our livelihoods. Humans have used lighting technology since long before industrialization. For many centuries, this lighting was extremely inefficient, with over 95% of the energy consumed wasted as heat. Recently, the Nobel Prize in Physics was awarded to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura for their remarkable contributions towards highly efficient light emitting diode (LED) technology. A day later, Michael Shellenberger and Ted Nordhaus reignited a long standing debate with an Op-Ed in The New York Times claiming that these developments are not likely to save energy and instead may backfire. (TheTimes has since corrected a crucial point of the article, and it has published three letters to the editor, including one by a subset of co-authors here.)

As evidence for these claims, Shellenberger and Nordhaus cite research that observes the vast improvements in the efficiency of lighting over the past two centuries having resulted in “more and more of the planet [being] dotted with clusters of lights.” They take this as evidence of how newer and ever more efficient lighting technologies have led to demand increases and, thus, have “led to more overall energy consumption.” Further, they refer to “recent estimates and case studies” that suggest “energy-saving technologies may backfire, meaning that increased energy consumption associated with lower energy costs because of higher efficiency may in fact result in higher energy consumption than there would have been without those technologies.”

First off, yes, it is likely that many efficiency improvements are associated with some rebound effect. It’s been with us forever, and it’s been known for over a century. More efficient lighting leads to people using more light. Key here is “leads to.” Causality matters. More on that in a minute.

For now, a quick look at the actual technology in question. It turns out the technology developments for LED lighting are, in fact, much greater than previous advances in lighting. Figure 1 [see the pdf] shows the dramatic pace of technology change in LED efficacy. The Nobel Prize was well-deserved: LEDs provide a major energy-saving innovation.

But what about the claim that this efficiency improvement will only lead to more energy use? This claim is simply not justified. Noting that lighting dots the globe at night today when it did not in the 19th century may be confounding correlation with causation. The world is also much wealthier today and the service provided by light from electricity is very different than candlelight. Perhaps earlier lighting would have dotted the globe at night in 1850 too had we been as wealthy as today and had consistent lighting. We cannot say without looking at the evidence.

The evidence we have is quite clear. Shellenberger and Nordhaus say “The I.E.A. and I.P.C.C. estimate that the rebound could be over 50 percent globally,” and they then proceed to talk about “backfire,” a rebound effect of over 100 percent. That’s quite a jump from 50 to 100. What’s missing here is that most studies, including the IEA’s and their own(!), take 60% as an upper bound. The IPCC summarizes the evidence as thus:

“A comprehensive review of 500 studies suggests that direct rebounds are likely to be over 10% and could be considerably higher (i.e., 10% less savings than the projected saving from engineering principles). Other reviews have shown larger ranges with Thomas and Azevedo (Thomas and Azevedo, 2013) suggesting between 0 and 60%. For household‐efficiency measures, the majority of studies show rebounds in developed countries in the region of 20-45% (the sum of direct and indirect rebound effects), meaning that efficiency measures achieve 65-80% of their original purposes.”

We have each performed our own detailed surveys of the literature (Azevedo 2014; Thomas & Azevedo, 2013Gillingham et al. 2013; Gillingham et al. 2014) and largely agree with these statements from the I.P.C.C. The bottom-line: the evidence for a “backfire” is weak. The rebound effect is clearly there, but first it’s generally relatively small—especially in developed countries. Perhaps most importantly, where it does exist—and it does—it’s good.

Energy inefficiency can’t be good. That doesn’t yet mean that efficiency alone is sufficient. Every economist worth his or her degree would conclude that we need a price on carbon or a similar instrument. Bonus fact: there’s no direct rebound effect with pricing mechanisms.

As the Nobel Committee notes in its press release: “The LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world who lack access to electricity grids.” In short, and as two of us say in a shorter letter to the editor, LEDs alone clearly won’t solve global warming, nor will they solve global poverty. But they are a step in the right direction for both. Thank you, Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura, and to the Nobel Committee for recognizing their work.

Published in full as part of a broader post on "Is There Room for Agreement on the Merits and Limits of Efficient Lighting" by Andrew Revkin on the DotEarth blog of The New York Times. For a shorter take, see our letter to the editor of The New York Times. For a longer take, see "The Rebound Effect and Energy Efficiency Policy."

Posted in Energy efficiency| Leave a comment

What if bees had value?

Episode 5 of Paul G. Allen and Morgan Spurlock’s We The Economy explores the hidden value of natural capital:

A Bee's Invoice from We The Economy, starring Adrian Grenier, Gernot Wagner, Jodi Beggs, and Robert F. Kennedy Jr.

Posted in 1000 words| Leave a comment

The Silver Bullet Of Climate Change Policy

From Forbes.com:

By Bob Litterman and Gernot Wagner

Whenever the conversation turns to climate change, someone is sure to opine that there’s no silver bullet. The issue is simply too complex to have one solution. When you focus on all the changes that need to occur to reduce greenhouse gas emissions globally it seems like a multifaceted approach is the only way forward.

Most of the world’s vexing problems share that feature. Mideast peace, nuclear non-proliferation, Eurozone stability, and plenty of other national security problems have no single right plan of attack. Some past plans might have brought us tantalizingly close to a seeming solution, but then reality started interfering once again, reconfirming the complexity of it all.

Climate change must surely be in that category. No single country, no single technology, no single approach can seemingly solve this one for us once and for all. Picking a single technology will almost inevitably end in some form of disappointment. Bureaucrats, the saying goes, ought not to try to pick winners. Leave that to venture capitalists for whom failure is a way of life. For every Apple and Facebook, there are dozens who never make it out of the garage. And clean technology doesn’t yet even have a single Apple and Facebook as the standout approach revolutionizing the field.

It turns out, though, that how you frame the issue is crucial. If you think like an engineer there are dozens of challenges. If you think like an economist, there is one. It’s guiding the ‘invisible hand’. How can you create the appropriate incentive to decrease the pollution that’s causing climate change? For that, the government need not be in the business of picking winners at all. What it should—and can—do is identify the loser that’s been clear for decades: greenhouse gas pollution. And the solution is equally clear: create incentives to reduce emissions by pricing it. If we make this one change, most other actions that are needed will follow.

That’s what the European Union has done by capping carbon emissions from its energy sector, including large industrials, covering almost half of total carbon emissions. That’s what California is doing with over 80 percent of its total global warming emissions. It’s what China is experimenting with in seven city and regional trials, including in Beijing and Shanghai. All these systems put a price on greenhouse gas pollution.

On the other side of the ledger, there are still much larger incentives to consume fossil fuels in many other countries. The International Energy Agency estimates that global subsidies are well over $500 billion. These subsidies, which incentivize emissions, sadly dwarf the paltry incentives to reduce them. Free marketeers, small government advocates, and others who dislike distorting government subsidies should be appalled at the tax money poured into fossil fuels.

There’s one simple principle that’s been around in economics for so long that no economist worth his or her degree would question the conclusion: increase the price, watch the quantity demanded go down. It’s such a universal truism that economists call it the “Law of Demand.” Generations of graduate students have estimated the effects of price on demand for anything from the generic widget to demand for car miles driven. People may be irrational at times, but one thing that we know for sure is that they respond to incentives.

Everything we know from decades of the study of human behavior would lead us to believe that carbon pollution will go down as the price on emissions increases. The only interesting question is by how much.

The prescription then for anyone seriously concerned about climate change is simple: price carbon to the point where its now unpriced damages are incorporated into the price, and get out of the way. It’s simple. It works. It’s conservative to the core.

It’s also a silver bullet solution if there ever was one.

Bob Litterman is a Partner at Kepos Capital, LP. Gernot Wagner is a senior economist at the Environmental Defense Fund.

Posted in Cap and Trade, Politics, Technology| 3 Responses

Why the cost of carbon pollution is both too high and too low

From EDF Voices:

Tell someone you are a “climate economist,” and the first thing you hear after the slightly puzzled looks subside is, “How much?” Show me the money: “How much is climate change really costing us?”

Here it is: at least $40.

That, of course, isn’t the total cost, which is in the trillions of dollars. $40 is the cost per ton of carbon dioxide pollution emitted today, and represents the financial impacts of everything climate change wreaks: higher medical bills, lost productivity at work, rising seas, and more. Every American, all 300 million of us, emit around twenty of these $40-tons per year.

The number comes from none other than the U.S. government in an effort to uncover the true cost of carbon pollution. This exercise was first conducted in 2010. It involved a dozen government agencies and departments, several dozen experts, and a fifty-page, densely crafted “technical support document,” replete with some seventy, peer-reviewed references and an even more technical appendix.

Cass Sunstein, the Harvard legal scholar of Nudge fame, who was co-leading the process for the White House at the time, recently declared himself positively surprised how the usual interest-group politics were all-but absent from the discussions throughout that process. This is how science should be done to help guide public policy.

The cost of carbon pollution is too low

The number originally reached in 2010 wasn’t $40. It was a bit more than half as much. What happened? In short, the scientific understanding of the impacts of rising seas had advanced by so much, and the peer-reviewed, economic models had finally caught up to the scientific understanding circa 2007, that a routine update of the cost of carbon number resulted in the rather dramatic increase to near $40 per ton. (There are twenty pages of additional scientific prose, if you want to know the details.)

In other words, we had been seriously underestimating the cost of climate change all along. That’s the exact opposite of what you hear from those who want to ignore the problem, and the $40 itself is still woefully conservative. Some large companies, including the likes of Exxon, are voluntarily using a higher price internally for their capital investment decisions.

And everything we know about the science points to the fact that the $40 figure has nowhere to go but up. The more we know, the higher the costs. And even what we don’t knowpushes the costs higher still.

Howard Shelanski, Sunstein’s successor as the administrator of the Office of Information and Regulatory Affairs (OIRA, pronounced “oh-eye-ruh”), has since presided over a further update of the official number. In fact, this one didn’t incorporate any of the latest science. It was simply a minor technical correction of the prior update, resulting in a $1 revision downward. (The precise number is now $37, though I still say $40 at cocktail parties, to avoid a false sense of precision. Yes, that’s what a climate economist talks about at cocktail parties.)

And once again, it all demonstrated just how science ought to be done: Sometimes it advances because newer and better, peer-reviewed publications become available. Sometimes it advances because someone discovers and fixes a small mathematical error.

Your input is needed

While announcing the correction, Shelanski added another layer of transparency and an opportunity for further refinements of the numbers: a formal call for public comments on the way the cost of carbon figure is calculated, open through January 27 February 26.

We are taking this opportunity seriously. EDF, together with our partners at the Natural Resource Defense Council, New York University School of Law’s Institute for Policy Integrity, and the Union of Concerned Scientists, is submitting formal, technical comments in support of the administration’s use of the cost of carbon pollution number as well as recommending further revisions to reflect the latest science.

The bottom line, as economists like to put it, is that carbon pollution costs society a lot of money. So as the technical experts trade scientific papers, you can help by reminding our leaders in Washington that we need strong, science-based climate policies.

Update (on January 24): The official comment period just was extended for another month, through February 26. More time to show your support.

Posted in Climate science| Leave a comment

Correcting the maths of the "50 to 1 Project"

(This post first appeared on Climate 411.)

A nine-minute video, released earlier this fall, argues that climate mitigation is 50 times more expensive than adaptation. The claims are based on calculations done by Christopher Monckton. We analyzed the accompanying “sources and maths” document. In short, the author shows a disconcerting lack of understanding of climate science and economics:

  1. Fundamental misunderstanding of basic climate science: Pre-industrial levels of carbon dioxide (CO2) were at around 280 parts per million (ppm).[i] One of the most commonly stated climate policy goals is to keep concentrations below 450 ppm CO2. Monckton, oddly, adds 280 and 450 to get to 730 ppm as the goal of global stabilization efforts, making all the rest of his calculations wildly inaccurate.
  2. Prematurely cutting off analysis after ten years: Monckton calculates the benefits of the carbon tax over a ten-year time horizon. That is much too short to see the full effects of global warming or of the policy itself. Elevated carbon levels persist for hundreds to thousands of years.[ii]
  3. Erroneously applying Australian “cost-effectiveness” calculation to the world: This may be the most troubling aspect from an economist's point of view. Monckton first calculates the effect of the Australia-only tax on global temperatures, which is unsurprisingly low, as Australia accounts for only 1.2% of world emissions. Next, he calculates the tax’s resulting “cost-effectiveness” — defined as the Australian tax influencing global temperatures. No surprise once again, that influence is there, but Australia alone can't solve global warming for the rest of us. Then, Monckton takes the Australia-only number and scales it to mitigate 1ºC globally, resulting in a purported cost of “$3.2 quadrillion,” which he claims is the overall global “mitigation cost-effectiveness.” But this number simply represents the cost of avoiding 1ºC of warming by acting in Australia alone. Monckton has re-discovered the fact that global warming is a global problem! The correct calculation for a globally applied tax would be to calculate cost-effectiveness on a global level first. If Australia’s carbon price were to be applied globally, it would cut much more pollution at a much lower cost. And that, of course, is very much the hope. Australia, California, and the European Union are called “climate leaders” for a reason. Others must follow.

What’s the real cost of cutting carbon? The U.S. government’s estimate of the cost of one ton of CO2 pollution released today is about $40.[iii] That's also the optimal price to make sure that each of us is paying for our own climate damages. Any policy with a lower (implied) carbon price—including the Australian tax—easily passes a benefit-cost test.

With all due respect Lord Monckton, 3rd Viscount of Brenchley, your maths are way off.


[i] "Summary for Policymakers," IPCC Fifth Assessment Report, Working Group I (2013).

[ii] Results differ across scenarios, but a rough rule of thumb suggests that approximately 70% of the ‘peak enhancement level’ over the preindustrial level of 280 ppm perseveres after 100 years of zero emissions, while approximately 40% of the ‘peak enhancement level’ over the preindustrial level of 280 ppm persevered after 1,000 years of zero emissions (Solomon, Susan, Gian-Kasper Plattner, Reto Knutti and Pierre Friedlingstein, “Irreversible climate change due to carbon dioxide emissionsProceedings of the National Academy of Sciences 106, no. 6 (2009): 1704-1709). Note that this refers to the net increase in carbon dioxide in the atmosphere, not the exact molecule. Archer, David, Michael Eby, Victor Brovkin, Andy Ridgwell, Long Cao, Uwe Mikolajewicz, Ken Caldeira et al. "Atmospheric lifetime of fossil fuel carbon dioxide." Annual Review of Earth and Planetary Sciences 37 (2009): 117-134 discusses these two often confused definitions for carbon’s ‘lifetime,’ and concludes that 20-40% of excess carbon levels remain hundreds to thousands of years (“2-20 centuries”) after it is emitted. Each carbon dioxide molecule has a lifetime of anywhere between 50 to 200 years, according to the U.S. Environmental Protection Agency’s “Overview of Greenhouse Gases: Carbon Dioxide Emissions.” The precise number is under considerable scientific dispute and surprisingly poorly understood. (Inman, Mason, “Carbon is forever,” Nature Reports Climate Change 20 November 2008)

[iii] The precise value presented in Table 1 of the Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis Under Executive Order 12866 for a ton of carbon dioxide emitted in 2015, using a 3% social discount rate increased is $38. For 2020, the number is $43; for 2030, the number increases to $52. All values are in inflation-adjusted 2007 dollars. For a further exploration of this topic, see Nordhaus, William D. The Climate Casino: Risk, Uncertainty, and Economics for a Warming World. Yale University Press (2013) as only one of the latest examples summarizing this kind of analysis. Nordhaus concludes that the optimal policy, one that maximizes net benefits to the planet, would spend about 3% of global GDP.

Many thanks to Michelle Ho for excellent research assistance.

Posted in Climate science, International, Politics| Leave a comment

New York Times op-ed: Inconvenient Uncertainties

By Gernot Wagner & Martin L. Weitzman

The headline in The New York Times yesterday was succinct. “By 2047, Coldest Years May Be Warmer Than Hottest in Past, Scientists Say.” Not, say, “around 2050” or “within our lifetime.” The specificity makes the crisis feel real, imminent and terrible. Call it a convenient truth.

The story was about a new study published this week in the journal Nature that calculated that by 2047, the average temperature will be hotter across most parts of the planet than it had been at those locations in any year between 1860 and 2005.

In truth, attention to the year 2047 is misguided. Climate around the world has already changed to a point where we can perceive humanity’s fingerprint. Extreme weather events like the two hurricanes that hit New York City in the past two years are going to be only more intense in the future.

Continue reading at nytimes.com/opinion.

Posted in Climate science| Leave a comment

Uncovering the Real Cost of Carbon

(This post was co-authored by Thomas Sterner and appeared first on EDF Voices.)

Last week, the Obama administration released new energy efficiency standards for microwaves, along with an update to the government’s official Social Cost of Carbon (SCC) figure. What do those two things have to do with each other? Well, the efficiency standards will help the planet by cutting the energy needs of microwaves, which will in turn save consumers money. And the new SCC numbers show just how expensive our addiction to fossil fuels has become.

The SCC is used to estimate the damages from carbon emissions (and the benefits from reducing those emissions) for the purposes of regulatory benefit-cost analyses. The central estimate for the SCC is now around $35 per ton of carbon dioxide pollution emitted today.

That’s the administration’s estimate of the damage—to human health, ecosystems, and the economy—caused by every ton of carbon dioxide emitted into the atmosphere. The average American emits about 20 tons each year.

The new cost of carbon figure is a welcome step forward, reflecting the latest versions of the underlying models. The bad news is that the increased number also shows that our lack of a comprehensive climate policy is becoming ever more costly.

Moreover, this updated SCC number underestimates the true costs of carbon emissions. For example, the current SCC quickly rises to $55 per ton under a lower discount rate (that is, an estimate that doesn’t “discount” harms to the wealth and health of future generations by quite as much as the administration did in reaching its $35 per ton figure).

The value of one ton of carbon dioxide would rise higher still with a declining discount rate, something that, in line with the general consensus among economists, would more closely reflect the true costs of climate change. And none of that includes the cost of extreme climate events.

Basing Policy on Science

The good news: the administration’s latest numbers show exactly how policy analysis should be done—rigorously and consistent with the latest advances in science and economics. For example, instead of using older versions of three main SCC models to calculate its official number, the administration now uses the most recent peer-reviewed versions of each. That simple but important step helps to bring the new official SCC more in line with the latest academic literature.

In short, the administration’s economics are slowly and carefully catching up with what we all can see outside our windows. While atmospheric carbon dioxide levels have just passed the 400 parts per million threshold for the first time in over 3 million years, the real costs of climate change keep piling on.

What the country really needs, of course, is for Congress to pass a comprehensive climate policy. Only then will Americans stop living in a world where their personal behavior leads to socialized costs of at least $35 for each of the 20 tons of carbon dioxide we emit every year. Until then, the Obama administration is right to at least include these costs in its own regulatory impact assessments.

Posted in Clean Air Act, Climate science, Politics| Leave a comment

Gross Domestic Product: Grossly incomplete, but we can fix it

Via EDF Voices. This first appeared online in an article posted at ensia.com.

Gross Domestic Product (GDP) is broken. Robert F. Kennedy said as much in his first major presidential campaign speech. Simon Kuznets, the father of GDP, acknowledged its shortcomings. GDP is an imperfect indicator of human well-being at best, and outright misleading at worst.

Still, we shouldn’t scrap GDP and start over.

Up to a point, GDP does tell us important facts about people’s lives, livelihoods and aspirations. Living on a dollar a day is miserable no matter how you look at it.

Choking on economic growth, of course, is equally bad. There are a few simple, well-established steps we ought to take to bring GDP closer to where we should be. That, by the way, isn’t “Green GDP” or “green accounting.” It’s honest accounting.

Start with accounting for the true value of natural assets still in the ground. We don’t “produce” coal. We extract it. And the fact that the ton of coal extracted today is no longer there for the taking tomorrow should show up in our national income accounts. A ton of West Virginian coal adds about $30 to GDP. Honest bookkeeping would decrease that amount to $15. The same holds for oil, trees, water and all the other valuable natural assets that fuel our economy but are largely treated as free in our GDP accounting.

Then quickly move on to pollution. Every ton of coal, every barrel of oil causes more in external damages than it adds value to GDP. Properly measured GDP ought to reflect that fact.

In the end, policy makers should expand their horizon and look at a dashboard of indicators to get a fuller picture of the true state of the economy, society and the planet. Yet when it comes to GDP itself, the name of the game is fixing it rather than scrapping it. We know how to do that. The U.S. Bureau of Economic Analysis is at the ready. Let’s have a go at it.

See the original post on ensia.com for a perspective from Sir Partha Dasgupta, Frank Ramsey Professor Emeritus of Economics at the University of Cambridge. 

Posted in Uncategorized| Leave a comment

Benefits of Clean Air and Water Dwarf Costs 10 to 1

(This post was first published on EDF Voices.)

The Office of Management and Budget is nerd heaven: a bunch of people getting their professional kicks from analyzing federal regulation. This bean counting may sound painfully lacking in glamour, but it’s incredibly important. OMB’s annual report to Congress on the benefits and costs of all major rules adopted by most federal agencies over the past 10 years shows how efficiently, or inefficiently, those agencies are functioning.  And the conclusion is clear: the Environmental Protection Agency comes out on top.

 

Source: OMB’s “Draft 2013 Report to Congress on the Benefits and Costs of Federal Regulations"

These numbers are based on the 2013 draft report, so they could still change. But the pattern is the same as in any of theirreports from the past few years, including the final 2012 report that came out last week.

None of this is to diminish the contributions of the other government agencies, but if you are a do-gooder trying to achieve the greatest good for the greatest number of people, EPA is the place to be.

One of the driving forces behind this rule is the Mercury and Air Toxics Standards, an extraordinary achievement for clean air and public health. Because of these standards, all coal fired power plants will for the first time be required to control their emissions of toxic air pollutants — including mercury, arsenic and acid gases. Forty years after the Clean Air Act signed by Richard Nixon, twenty after the landmark Amendments signed by George H.W. Bush, we are finally getting around to regulating mercury from burning coal.

The analysis of the benefits of reducing mercury pollution demonstrates just how much we underestimate the benefits of environmental protections. For example, when it comes to reducing mercury pollution, the benefits are based on EPA’s estimates of increased wages of (higher IQ) children born to families that catch freshwater fish for their own consumption.

Think about that one for a second. Mercury is a potent neurotoxin in all its forms, but the EPA estimates do not include mercury that is inhaled or that enters our bodies through other means. And there is nothing in the estimates about the fact that mercury harms the brains of our kids, regardless of whether it influences their future earning potential.

In a sense, this analysis is the moral equivalent of arguing that we should have child labor laws because keeping kids in school makes for more productive workers later on. This kind of reasoning, alas, is  why economists are often called names unfit for a family-friendly blog. It’s the most reductionist argument you can find in favor of reducing mercury. (In fact, the bulk of the benefits that were quantified by EPA are due to inextricably connected benefits in reducing deleterious particulate pollution.)

Costs, by the way, are relatively well estimated, since businesses are all-too willing to share them. So yes, there are costs—but they are small relative to benefits. And costs, as opposed to benefits, are typically overestimates. They are largely based on current available control technologies. They don’t consider that industry may invent an entirely new and unexpected way of complying with regulations at lower cost. This happens over and over again, and it comes with a name: entrepreneurial ingenuity. Works every time.

These omissions and shortcomings on either side of the equation only stand to bolster the most important claim: benefits outweigh costs more than 10 to 1 for all major EPA regulations adopted in the past decade.

For every dollar invested, Americans get $10 worth of benefits. I’ll take that ratio any day.

Posted in Clean Air Act, Politics| Leave a comment

Follow the Plastic Bag Example, Nudge Polluters to Pay

(This post was first published on EDF Voices.)

Nudge is the best kind of book. It presents the type of head-slappingly obvious solutions to public policy problems that make you wonder why you needed a book to tell you about them in the first place. Place the veggies before the French fries in the cafeteria, and people will eat more greens. Enroll employees into retirement programs with the option of opting out rather than in and they’ll save more as a result.

Such nudges are the best kinds of policy interventions: minimum intrusion, maximum freedom of choice, maximum relative impact. But one area in which Nudge comes up short is global warming. Putting smiley faces on your electricity bill as a reward for using less electricity than your neighbor, something oPower has done with utilities around the country, helps bring down electricity use by 1 to 3%. Better than zero, but not the solution by a long shot.

That solution would be making polluters pay: putting a price on carbon dioxide through a direct cap or tax on carbon pollution. Cass Sunstein, who wrote Nudge with Richard Thaler, says as much in his latest piece on the topic. He laments the fact that we don’t seem to be able to get these kinds of taxes passed, and then adds a few items to his running list of things we can do, all under the broad heading of setting “clean-energy default rules”: Change the default printer setting to “print on front and back,” and people will. Enroll people into programs where they spend extra for clean energy (with the option of opting out), and 90% will choose to stick with the clean energy.

All these proposals represent the best of what nudges ought to be. Policymakers need to set defaults either way. So set them in the way that goes furthest toward achieving your goal. Just that there’s still a big gulf between the policies we know are necessary and what appears to be doable.

The plastic bag solution

But there is one policy that seems to bridge the gap between the type of non-intrusive nudges Sunstein champions and the type of policies he knows are ultimately necessary to do something about global warming. They’re called bag taxes.

In 2002, Ireland started charging shoppers 15 eurocents a plastic bag. The result: bag use plummeted 90 percent. That's a billion bags a year.

In 2010, Washington, D.C., began charging 5 cents per disposable bag, paper or plastic. As a result, plastic bag usedeclined 80 percent within a year by some estimates.

These fees are tiny. Compared to the $100 worth of groceries you’ll be carrying home in your bags, they might as well be zero. The point is that they are not. The fees are big enough to change the default behavior of shoppers. A few pennies (and the odd public information campaign) are all it takes to motivate shoppers to bring reusable bags to the store.

It’s quite a leap from plastic bags to carbon prices. The principle is the same: It’s the price that counts—a price that is directly connected to an action. Change the action (stop using plastic bags) and you avoid the fee. Similarly, increase the price of carbon, watch carbon pollution fall. This price-up-demand-down relationship is so well established, it’s one of the very few actual “laws” economists have. Violations are tough to find. Plastic bags and carbon certainly don’t violate this common sense principle.

Bag fees and carbon prices have this important feature in common. They don’t just nudge, they also charge consumers for the cost of their—our—actions. For carbon dioxide, there are plenty of studies that estimate the cost to society of this type of pollution. The right price for each ton of carbon dioxide would be at least about $20. Given the fact that the average American emits his body weight worth of carbon dioxide every day and a half, that comes out to about $1 per day. Double it to account for the fact that there are plenty of damages we haven’t yet incorporated in the official number, and doing something serious about global warming is still a bargain at $2 per person per day.

As an insurance policy against the worst effects of global warming, that’s tiny. Never mind how small a price, though, the politics of actually doing it are tricky, to say the least. The plastic bag lobby just isn’t as important as the fossil lobby. And bag fees can be implemented on the local level. A carbon price can’t. It requires Congressional action, a seeming oxymoron these days. Even with carbon, though, states—if not cities—can lead the way. Look no further than California and its comprehensive cap-and-trade system. It limits carbon pollution with a firm, declining cap, giving Californian businesses maximum flexibility in how to make their operations more efficient and innovate their way out of the high-carbon, low-efficiency bind. That ought to be a template for the nation.

Meanwhile, we can do a lot worse than look to plastic bag fees as a model for the kinds of policies that we know are necessary to tackle global warming. Cass Sunstein, the co-author of Nudge, and Cass Sunstein, the policy analyst calling for a price on carbon pollution, would approve.

Posted in Politics| Leave a comment