(This post first appeared on EDF Climate Talks.)

While Washington is stuck in gridlock, other jurisdictions around the world are moving forward on climate policy.

Market-based approaches to cutting carbon are in place in jurisdictions accounting for nearly 10% of the world’s population. Above: areas shaded blue have emissions trading programs that are already operating; areas in green have programs that are launching or being considered.

Market-based approaches to cutting carbon are already in place in jurisdictions accounting for nearly 10% of the world’s population and more than a third of its GDP. Many more jurisdictions are either moving ahead with market-based measures, or actively considering them.

As interest grows around the world, policymakers are increasingly seeking information about the range of existing and proposed initiatives.

In response, EDF has partnered with the International Emissions Trading Association (IETA), a trade association that represents businesses involved in carbon trading and climate finance, to launch The World's Carbon Markets: A case study guide to emissions trading.

The online resource provides detailed information about key design elements and unique features of 18 emissions trading programs that are operating or launching around the world.

EDF has also put together a quick reference chart that makes comparing the 18 programs even faster and easier.

Growing interest in emissions trading

Market-based policies are a proven way to limit carbon pollution and channel capital and innovation into clean energy, helping to avert the catastrophic consequences of climate change.

While emissions trading programs around the world, like the ones we have looked at in detail, vary in their features, they all share the key insight that well-designed markets can be a powerful tool in achieving environmental and economic progress.

The countries, states, provinces and cities highlighted in this report, which are moving ahead with strong action on climate change, constitute a vital and dynamic world of “bottom-up” actions that complement multilateral efforts such as the ongoing United Nations climate negotiations.  Jurisdictions considering market-based approaches can use this new resource to learn from their growing number of peers already headed in that direction.

(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.

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. 

(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.

(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.

(Note: This post was co-written with Graham McCahan and was first published on EDF Voices.)

Congress may be ignoring climate change these days, but there are laws already in place that make progress possible, right now, on this defining issue.

Take the Clean Air Act. Under it, the President has begun to use his authority – as confirmed by the U.S. Supreme Court – to regulate greenhouse gases in a serious way.

The Global Change Research Act is another, lesser known law that could have a major impact on the national understanding of what climate change is doing to our world.

Congress passed the Act in 1990 to provide for “a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.” What that means, in part, is that the government must prepare a National Climate Assessment every four years. The next report is due out this June.

April 12 was the deadline for public comments on the draft report.

A lot has happened since the last assessment in 2009. The country has begun to experience the effects of climate change: droughts, floods, heat waves, two hundred-year storms hitting New York City within two years. The abnormal is becoming the new normal. (True, no single such event can be conclusively linked to the fact that the average American emits carbon dioxide equal to his body weight every day and a half. But that’s like saying that no single Barry Bonds homerun or Lance Armstrong Tour de France win can be linked to doping.)

This year’s quadrennial report should set the standard as an analysis of these phenomena. Thus far, the draft assessment, written by some of the nation’s leading scientists and experts, is rich in sobering data and analysis on things like extreme weather and the damage it is causing. But its consideration of the economic impacts of climate change – the enormous and rising costs — is scattershot and incomplete.

For example, the draft report shows that the 2011 Texas drought cost farmers and ranchers in that state over $5 billion. And it tells us that wastewater utilities will have to spend between $120 billion and $250 billion by 2050 to adapt their infrastructure to a changed climate. But the draft makes no attempt at a rigorous estimate of the costs of climate change, or the rising costs of inaction in the face of it.

Between now and June, this weak spot needs to be shored up by the report’s authors.

EDF, in its official comments to the National Climate Assessment, is urging that it incorporate all relevant information on the economics of climate change, whether from the federal government or the private sector. That’s the only way to get a handle on the costs that climate change is levying on each and every one of us.

Recently, for example, the independent, nonpartisan, U.S. Government Accountability Office, warned that climate change “presents a significant financial risk to the federal government” in four key areas:

1) Damage to federal property and infrastructure, and associated adaptation costs.

2) Rising costs for federal insurance programs. For instance, the federal government’s crop insurance costs have increased from an average of $3.1 billion per year from 2000 through 2006 to an average of $7.6 billion per year from 2007 through 2012; and these costs are projected to increase further.

3) Costs related to providing assistance to state and local governments to respond to local climate impacts.

4) Rising costs of climate disaster relief. For example, federal disaster declarations have increased over recent decades, and the Federal Emergency Management Agency (FEMA) obligated over $80 billion in assistance for disasters from 2004 through 2011. The growing number of disaster declarations—a record 98 in fiscal year 2011 compared with 65 in 2004—has contributed to increased federal disaster costs.

Material like that should be included in the final assessment.

The same holds true for data from the private sector. In a recent report, the world’s largest reinsurance company, Munich Re, analyzed the costs of severe weather in North America. It found that the number of natural catastrophes escalated from 1980 through 2011, as did the losses for weather-related events during the same time period – both insured and uninsured. The total losses from weather catastrophes over these three decades exceeded $1.06trillion. About half, $510 billion, were insured losses. The rest wasn’t. All of it was ultimately born by all of us – whether in increased taxes or insurance premiums, or directly out of our wallets.

The Global Change Research Act compels the government to make a definitive assessment of what climate change is doing to the nation’s health and welfare. In that spirit, the National Climate Assessment, when it is released in June, should strive to be the last word on the issue – to set the terms of the debate.  And let’s hope it also helps move our elected leaders to action.

One of the goals of EDF’s Ecosystems work is to provide farmers with revenue opportunities in reducing their greenhouse gas (GHG) footprint. Under AB32, California’s landmark legislation aimed at reducing GHG emissions, regulated entities may purchase carbon offsets to meet up to 8% of their obligations. Over the past six years, EDF has worked closely with growers to capitalize on the anticipated demand for these offsets, by developing protocols that will allow landowners to generate and sell agricultural offsets. On March 28, we reach a milestone in these efforts: the California Air Resources Board will host a workshop to begin a rulemaking process to consider the adoption of an offset protocol EDF has developed with the American Carbon Registry, crediting rice producers for GHG abatement practices.

We’ve put a great deal of work into understanding and piloting a myriad of rice farming techniques, while studying their implications for GHG emissions. A major conclusion from our analysis is that there exists a subset of viable alternative practices for rice producers in California with potential agronomic, economic and environmental benefits. The ones we’ve decided to focus on for our offset protocol are: baling, dry seeding, and early drainage of fields before harvest.

Agricultural activities account for an estimated 12% of global GHG emissions – the majority of these arise from sources of nitrous oxide and methane gases, composing ~60% and ~50% of the global total, respectively (as of IPCC AR4). Rice cultivation accounts for 5-20% of worldwide methane emissions; much of it is emitted as a byproduct of organic decomposition under flooded paddies. California’s goal to reduce its emissions to 1990 levels by 2020 through its cap-and-trade program (AB32) provides an opportunity for rice farmers to help the state meet its reduction goal.

There are multiple approaches for rice farmers to reduce GHG emissions. Some of these practices can be carried out before the harvest and others post-harvest. We’ve carried out some in-depth analysis on the various options, to better understand the incentives and revenue possibilities we will be encouraging through our policy work – we have found that there are a handful of ways that farmers can reduce GHG emissions while maintaining yields, earning some revenue for their efforts, and potentially save on costs in some circumstances.

Our analysis builds on a prior study by our partners Applied Geosolutions, UC Davis and the California Rice Commission that estimates GHG emissions and yields for the majority of rice producing acreage in the state. They use the DeNitrification-DeComposition (DNDC) model, simulating 6,316 rice fields for 16 farming practices. In our analysis, we first estimate the potential greenhouse gas abatement of a suite of specific practices: dry seeding the rice fields, baling harvest residue, and hydroperiod adjustments (draining of fields in midseason, before harvest and/or reducing winter flooding).

We then tabulate the cost of each management practice through a combination of literature, farmer and farm advisor consultation and combine these with abatement estimates to generate marginal abatement cost curves for each practice. Our preliminary results indicate a wide variability in abatement costs, depending on farming conditions. Of course, this is before factoring in the role of a carbon credit.

Unfortunately, not all of the practices we’ve studied are tenable in the Californian setting. One practice (midseason drainage of the fields) is accompanied with a significant decrease in yield and therefore does not lend itself well to the Sacramento Valley climate. In the case of stopping winter flooding, there could be negative habitat impacts for waterfowl that use this ecosystem as a feeding ground. Striving to understand such risks has been crucial in determining the extent to which producers will consider the new incentives created through the market.

Because the practices listed above have not been widely adopted, they are key opportunities for the generation of offsets.  To better understand adoption rates, EDF is conducting further research in determining the quantitative and qualitative barriers that are limiting farmers from adopting such farming methods.

California will be one of the first rice producing regions in the U.S. to present abatement opportunities in conjunction with a carbon market. Combining economic principles such as abatement cost curves with biogeochemical models (e.g. DNDC) is useful in studying such opportunities. Further, the ability to simulate practices at the field level is central to understanding the economic potential of offset protocols granting agricultural producers access to carbon markets. In turn, this can create new incentives to abate GHG emissions from agriculture while potentially providing new sources of revenue to landowners – potentially a win-win situation.

We are excited that Thursday’s California Air Resources Board workshop will kick off the rulemaking process and that farmers can soon benefit from these interesting prospects.

Few Thais recycle, no one bikes, plastic bags are everywhere and Bangkok is afflicted by gridlock and pollution. So you might say that, in general, Thais behave more like citizens of a rapidly emerging economy than the typical Brooklyn environmentalist.

Why, then, does virtually every home use efficient compact fluorescent lights (CFLs). Americans and Europeans needed a ban on incandescent bulbs to make the switch. Not so the Thais, where you can still buy cheaper, more inefficient incandescent bulbs at the corner store.

Was it the influence of a higher authority? Thais famously revere their 85-year-old King, the world’s longest-reigning head of state, who happens to be an environmentalist.

The answer is, mostly, no.

Continue reading at EDF Voices.

As the second auction in California’s landmark cap and trade program approaches, a coalition of states on the opposite side of the country – that have been cost-effectively reducing their carbon pollution while saving their consumers money – announced plans to strengthen their emission reduction goals.  Last week, the Regional Greenhouse Gas Initiative (RGGI) – the nation’s first cap and trade program which sets a cap on carbon dioxide pollution from the electric power sector in 9 Northeastern states (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont) – released an updated Model Rule containing a number of improvements to the program, primarily a significantly lower (by 45%) overall cap, realigning it with current emissions levels.

Since the program took effect in 2009, emission reductions in the RGGI region have occurred faster and at lower cost than originally expected.  This has primarily been the result of increased electric generation from natural gas and renewables which have displaced more carbon-intensive sources like coal and oil, as well as investments in energy efficiency that lower overall electricity demand.  These reductions have been accompanied by lower electricity prices in the region (down 10% since the program began) and significant economic benefits:  a study from the Analysis Group estimated that electric consumers would save $1.1 billion on their bills over 10 years from the energy efficiency improvements funded by allowance revenue, and further, that these savings would generate over $1.6 billion in economic benefits for the region.

The new lower cap allows RGGI to secure the reductions already achieved, and push forward towards more ambitious pollution reduction goals.  The changes to the program are the result of a transparent and comprehensive program review process set in motion through RGGI’s original Memorandum of Understanding – a mechanism that is successfully fulfilling its original intention by allowing the states to evaluate results and make critical improvements.

While the changes will go a long way to fortify the program, there is room in the future for the RGGI states to look to California’s strong program design for additional enhancements.  For example, RGGI’s updated Model Rule creates a Cost Containment Reserve (CCR) – a fixed quantity of allowances which are made available for sale if allowance prices exceed predefined “trigger prices”.  A CCR is a smart design feature which provides additional flexibility and cost containment – however, RGGI’s CCR allowances are designed to be additional to the cap, rather than carved out from underneath it as in CA’s program (ensuring the overall emission reduction goals will be met).  California’s program has displayed enormous success already, with a strong showing in their first auction.

In the meantime, the RGGI states should be commended for their success thus far, and for their renewed leadership as they take important steps to strengthen the program.  These states have achieved significant reductions in emissions of heat-trapping pollutants at lower costs than originally projected, all while saving their citizens money and stimulating their economies, transitioning their power sector towards cleaner, safer generation sources, and laying a strong foundation for compliance with the Carbon Pollution Standards for power plants being developed under the Clean Air Act.  Such impressive achievements provide a powerful, concrete example of how to tackle harmful carbon pollution and capture the important co-benefits of doing so.

The bottom line is that cap and trade is alive and well on both coasts as the states continue to lead the charge on tackling climate change in the U.S. while delivering clear economic benefits.

Trying to put the rebound effect for energy efficiency in its rightful place is like playing a game of wack-a-mole. Predictably every couple of years, someone new discovers the counter-intuitive appeal of showing how more efficient energy policies may lead to more energy use. Wham! Told you there's something wrong with those clean-car standards. Well, not so fast.

Yes, the rebound effect is real. But it's also small. And what's there is actually positive! Why shouldn't people who can now afford to due to more efficient energy technologies be able to improve their lives?

Together with three co-authors (Ken Gillingham at Yale, Dave Rapson at University of California, Davis, and Matt Kotchen, currently on leave from Yale to serve as Deputy Assistant Secretary for Environment and Energy at the U.S. Treasury), I surveyed a bajillion+1 energy efficiency rebound studies. Nature then made us cut down those references to 6. We settled at 9.

We couldn't find a single study that has the rebound be above 100% or anything close to it, what's necessary to nix energy efficiency savings. The maximum number you can get is 60%, and that's already quite a stretch. Think 30% as the upper bound for actual behavioral responses. Yes, we are more efficient today than we were a hundred years ago, and we also use more energy today. But that's far from talking about the rebound effect. It's simply economic growth.

Establishing a causal link between efficiency and energy use isn't quite as simple. In the end, the rebound effect comes in four forms. Buy a more fuel-efficient car, and driving that next mile just became cheaper. The result: a bit more driving, to the tune of 5 to a maximum of 30%, although most likely much closer to 5-10% of the initial fuel savings. Then there's the indirect effect: Drivers may now use some of the savings to buy other products that consume energy.

You can already see that we can't just add these two effects. If you spend some of the gas money on driving more, you have less to spend on that plane ticket, and vice versa.

Then there are two macroeconomic effects: one via the price and one via technological advances. They are the trickiest to pin down and could, in theory, be the largest. But theory lends a helping hand in getting an upper bound: the basic demand-and-supply relationship tells us that the macroeconomic price effect can't be more than 100%.

And once again, all these effects aren't anywhere near that threshold. 60% is as high as it gets for the combined effect, and only in rare circumstances. For the most part, it's much closer to 5 to perhaps 30%.

So where does that leave us?

When designing energy efficiency policies like clean-car standards, consider the rebound effect, much like the government already does. The Department of Energy's model uses a highly appropriate 10% rebound figure for the car standards. And that's about it. Not much else to see here.

If you did want to take it a step further — full disclosure: a step I couldn't convince my three co-authors to take in the Nature piece itself — everything else equal, the existence of the rebound effect may prompt us to use even stricter energy efficiency standards. If you have an overall target in mind, and the rebound effect shaves off a bit, you ought to consider using a slightly stricter target to get back to where you wanted to be.

For more, check out the full Nature piece. Well worth the $32 to put the rebound effect in its rightful place once and for all.