Misleading Talk about Decoupling CO2 Emissions and Economic Growth

You can call it my pet peeve or even my obsession, but whenever I read about the claimed “decoupling” of CO2 emissions and economic growth, I get annoyed.  Webster’s Dictionary defines decoupling as “eliminating the interrelationship” between two processes.  But the interrelationship between CO2 emissions and economic growth has certainly not been eliminated.

Decoupling is the wrong word and metaphor to describe what has been happening.  When a caboose is decoupled from a train, it stops moving altogether.  A better metaphor, although less linguistically appealing, would be a “slipping clutch.”  The engine continues to transmit power, and as a result the driveshaft continues to rotate, but with less velocity than when the clutch was new.

What Has Been Happening

True enough, the carbon intensities of many economies in the world, particularly those of the industrialized nations, have – for many years – been falling, as those economies have become less energy intensive (less energy use per unit of economic activity – Gross Domestic Product or GDP), and therefore less carbon intensive.  For each dollar of economic activity, CO2 emissions are less than they used to be.  For each unit of economic growth, there is less growth in CO2 emissions than previously.

Furthermore, in some cases, as economies grow, CO2 emissions can actually fall.  First, picture an economy which is growing exclusively in its services sector.  In this case, economic growth might be accompanied by no change in CO2 emissions.  Now picture an economy which is growing in its services sector, while shrinking in its manufacturing sector (sound familiar?).  In this case, economic growth might be accompanied by reduced CO2 emissions.  Now add to this picture the presence of some public policies, such as those that cause the closure of coal-fired electric generation plants, as well as greater dispatch of electricity from natural gas-fired plants.  The result:  economic growth continues, with falling CO2 emissions.  But there has been no decoupling.

Confusion Due to Failure to Employ Appropriate Counterfactual

The problem and the confusion arises from a very common mistake in the popular press and, for that matter, in many casual conversations:  failure to use the right counterfactual for analysis.  The fact that GDP is rising while emissions are falling does not mean that GDP is not affecting emissions.  The appropriate counterfactual for comparison is how much would emissions have fallen had there been no growth in GDP.  Presumably, emissions would have fallen even more.  The excess of emissions in the factual case, compared with the counterfactual case, is the magnitude of emissions growth due to (actually, “associated with”) economic growth.  There has been no elimination of the relationship between the two, although the nature and the magnitude of that relationship has changed.

What Factors Affect CO2 Emissions?

So, why have CO2 emissions been declining in some countries?  Or, more broadly and more to the point, what factors have affected CO2 emissions?  Four stand out (although there are others).

First, energy comes at a cost in all economies, and so economic incentives exist to economize on energy use through technological change.  The energy-intensity of the U.S. economy has gradually fallen – almost monotonically – since early in the twentieth century.

Second, putting aside energy-intensity and focusing on carbon intensity, some technological change has worked against the use of carbon-intensive sources of energy.  The most dramatic example, specific to the United States, has been the combination of horizontal drilling and hydraulic fracturing (fracking), which has caused a significant increase in supply and dramatic fall in the market price of natural gas, which has thereby led to a massive shift of investment and electricity dispatch from coal to natural gas.

Third, in the richer countries of the world, including this one, the process of economic growth has led to changing sectoral composition:  heavy industry to light manufacturing to services.  The deindustrialization of California is a graphic example.  Does the fact that California’s economy has grown while emissions have fallen mean that decoupling has occurred?  Of course not.  And, in the California case, there has also been a fourth factor …

Fourth, public policies have in some jurisdictions of the world (Europe, the United States, and most of the other OECD countries) discouraged carbon intensity.  In the USA, this has happened both through climate policies and other, non-climate policies.  Some non-climate policies, such as EPA’s Mercury Rule, discourage investment, encourage retirement, and discourage dispatch of coal-fired electricity, while other non-climate policies, such as CAFE standards for motor vehicles, bring about greater fuel efficiency of the fleet of cars and trucks over time.  Climate-specific policies have also mattered, such as in California, where the Global Warming Solutions Act of 2006 (AB-32) has brought down emissions through a portfolio of policies, including an economy-wide CO2 cap-and-trade system.

The Bottom Line

So, yes, the carbon intensity of many economies continues to fall – for a variety of reasons, including but by no means limited to public policies.  And, in some cases, the combination of energy price changes, technological change, changes in sectoral composition, and climate and other public policies has meant that emissions have fallen in years when economic growth has continued.  But don’t be fooled.  Economic growth does affect CO2 emissions.  There has been no decoupling; just some (desirable) slipping of the clutch.

Of course, this is not an anti-environment message.  On the contrary, a belief in decoupling per se could lead to a misguided laissez-faire attitude about the path of CO2 emissions.  Being honest and accurate about the links between (desirable) economic growth and (desirable) CO2 emissions reductions puts our focus and emphasis where it ought to be:  finding better ways to have both.

A Key Element for the Forthcoming Paris Climate Agreement

The upcoming Paris climate negotiations will constitute a critical step in the ongoing international process to reduce global greenhouse gas (GHG) emissions. The question of whether the Paris outcome will be sufficiently ambitious to put the world on a path towards limiting global average warming to 2o C, as agreed in Cancun, can be answered now.  It will not, because that target, while possibly useful as an aspirational goal, is not achievable, as the most recent report of Working Group III of the IPCC documented. What is clear, however, is that greater ambition is more easily realized when costs are low. Market-based mechanisms are an important element in the portfolio of actions that can lead to cost-effective solutions. Linkage – between and among market and non-market systems for reducing GHG emissions – is a closely-related key element.

In an article just published in Climate Policy, “Facilitating Linkage of Climate Policies through the Paris Outcome,” my co-authors – Daniel Bodansky of Arizona State University, Seth Hoedl of Harvard Law School, and Gilbert Metcalf of Tufts University – and I examine how the Paris outcome, and more generally the ongoing climate negotiations, can allow for and advance linked systems.

Brief Background

In the Durban Platform for Enhanced Action, adopted by the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) in 2011, the parties agreed to develop a “protocol, another legal instrument or an agreed outcome with legal force under the Convention applicable to all Parties,” for adoption at COP-21 in December, 2015, in Paris. It is likely that the Paris outcome will reflect a hybrid climate policy architecture – one that combines top-down elements, such as for monitoring, reporting, and verification (MRV), with bottom-up elements, including “Intended Nationally Determined Contributions” (INDCs), describing what a country intends to do to reduce emissions, based on domestic political feasibility and other factors. This outcome will be embodied in a core agreement, which likely will be legally binding, as well as ancillary instruments such as annexes, national schedules, and COP decisions.

The ability to link regional, national, and sub-national climate policies will be essential to enhancing the cost-effectiveness of such a system – and thus the likelihood of achieving significant global emissions reductions. By ‘linkage’, we mean formal recognition by a GHG mitigation program in one jurisdiction (a regional, national, or sub-national government) of emission reductions undertaken in another jurisdiction for the purposes of complying with the first jurisdiction’s requirements.

First Necessity for Paris: Do No Harm

The minimum requirement for the Paris agreement in regard to linkage is to do no harm. Silence on linkage could possibly accomplish that. But any provisions in the agreement that would require nations to achieve their respective INDCs exclusively within their own borders – a constraint that has been favored by the ALBA countries – would, in effect, prohibit not only international carbon markets but any sort of meaningful linkage (and would thereby greatly drive up costs).

Common Definitions of Key Terms

If linkage is to play a significant role in a hybrid international policy architecture, then several categories of design elements merit serious consideration for inclusion in the Paris outcome, either directly or by establishing a process for subsequent international negotiations. In general, effective linkage requires common definitions of key terms, including particularly the units to be used for compliance purposes. This will be particularly important for links between heterogeneous systems, and it is an area where a model rule could be particularly helpful (more about this below).

Registries and Tracking

Linkage requires registries and tracking mechanisms, whether the systems being linked are homogeneous or heterogeneous. Indeed, a key role for the top-down part of a hybrid architecture that allows for international linkage of national policy instruments will be the tracking, reporting, and recording of allowance unit transactions.

International compliance units would make the functioning of an international transaction log more straightforward and reduce the administrative burden of reconciling international registries with national registries. Minimum standards for approving and measuring offsets may be important. Market oversight and monitoring may increase confidence in the system, although in some cases, national and international institutions that can provide oversight already exist and may need only relatively minor additional capacity to assume these functions.

Too Much of a Good Thing Can be Bad

Including detailed linkage rules in the core agreement is not desirable as this could make it difficult for rules to evolve in light of experience. Instead, minimum standards to ensure environmental integrity should be elaborated in COP decisions, or by other means; for example, the COP could establish minimum requirements for national monitoring, reporting, and verification (MRV), registries, and crediting mechanisms.

In terms of linkage, the function of the core agreement might be confined to articulating general principles relating to environmental integrity, while also authorizing the COP or another organization to develop more detailed rules. Whatever minimum standards are adopted, oversight of compliance will be important to ensure the integrity both of the Paris outcome and of linked national systems.

The Utility of Default or Model Rules

Many elements of GHG linkage can be addressed through default or model rules from which nations are free to deviate at their discretion. Rules that may benefit from this approach are typically concerned with the details of linking two regulatory systems. For example, nations interested in linking their cap-and-trade systems would have to consider rules for market coverage, cost containment, banking and borrowing, compliance periods, allocation methods, and the treatment of new emitters and emitter closures. Additional rules may be needed for linking of heterogeneous systems.

Developing uniform rules to address all of these issues is unrealistic. Instead, a degree of harmonization could be achieved through default rules that facilitate linkage by providing a common framework for nations to use when developing their own linkage agreements. Although there is no need for the core agreement itself to elaborate harmonized linkage rules, it might authorize the COP to develop default linkage rules that nations can use in negotiating bilateral linkage agreements.

Less is More

In our Climate Policy article, Dan Bodansky, Seth Hoedl, Gib Metcalf, and I conclude that the most valuable outcome of Paris regarding linkage might simply be the inclusion in the core agreement of an explicit statement that parties may transfer portions of their INDCs to other parties and that these transferred units may be used by the transferees to implement their INDCs. Such a statement would help provide certainty both to governments and private market participants. This minimalist approach will allow diverse forms of linkage to arise, among what will inevitably be highly heterogeneous INDCs, thereby advancing the dual objectives of cost effectiveness and environmental integrity in the international climate policy regime.

Crude Oil Prices, Climate Change, and Global Welfare

A few weeks ago, I participated in a panel session titled, “The Remarkable Transformation of the Energy Sector: Does it Also Transform Our World.” The motivating question was: “Is the dramatic decline in oil prices a complete gift to the West because of the enormous funds being saved, or is it an unintended Trojan horse because development of renewable energy as well as new fossil-fuel sources will decline in the West, posing longer new challenges?”

The other members of the panel – from private industry – had vastly more expertise (and relevant insights) on fossil-fuel markets, but here’s what I had to say. This is hardly at the sweet spot of my professional competence, so I welcome your comments and corrections! In general, how would you answer that question?


I start (and started) from the premise that the dramatic decline in crude oil prices that took place from August, 2014 ($96/barrel), to March, 2015 ($44/barrel), was due – on the one hand – to decreased demand, a function of slow economic growth in Asia, Europe, and elsewhere, endogenous, price-driven technological change leading to greater fuel efficiency, and policy-driven technological change that also has been leading to greater fuel efficiency, such as more stringent Corporate Average Fuel Economy (CAFE) standards in the United States; and – on the other hand – was due to increased supply, partly a function of the growth of unconventional (tight) U.S. oil production (a product of the combination of two technologies – horizontal drilling and hydraulic fracturing).  And, in the presence of all of this, Saudi Arabia decided not to restrict its output to prop up prices.

[Before proceeding, I should note that since May of this year, crude oil prices have increased by about 30% from their March low, but as of May ($60/barrel) are still far below their August 2014 level.]


When one examines virtually any significant price change from an economic perspective, there inevitably seems to be both good news and bad news. So with the fall in crude oil prices.

The Bad News

First of all, I assume that low crude oil prices are problematic for the economic and political stability of some of the oil-producing/exporting countries, including Saudi Arabia, Russia, Venezuela, and Nigeria.  (For details, see Bordoff and Losz 2015, below.)

Second, it’s frequently been asserted that low oil prices are bad news for the development of alternative forms of energy, including renewable sources. Of course, in the United States, there isn’t much effect on electricity generation from renewable (wind and solar), because in the U.S. electricity sector, renewable supplies compete with coal and natural gas, not with fuel oil (but in other countries, which use more fuel oil for electricity generation than we do, there can be a disincentive for renewable dispatch – and hence development).

Third, there can be – indeed, has been – a major impact in the U.S. motor fuels sector, where the market for biofuels (mainly ethanol) is negatively affected by low conventional gasoline prices. However, these impacts must be somewhat muted by public policies, which directly or indirectly subsidize (or, in fact, require) the use of biofuels.

Fourth, low gasoline prices have resulted in decreased demand by consumers for motor vehicles with high fuel efficiency, and SUV and pickup truck sales have rebounded from previous lows. But these effects are also muted, to some degree, by public policies, including U.S. CAFE standards.   Finally, low gasoline prices also have short-term effects in the form of more driving and fuel use by the existing fleet of motor vehicles, which is bad news in terms of emissions (and congestion).

Differences across Sectors

Before turning to the “good news” about low crude oil prices (and there surely is good news), it’s worthwhile noting that whether individual businesses find these low prices to be good or bad depends largely upon the economic sector in which they operate. For example, whereas commercial airlines are finally making profits, due to the low price of jet fuel (their most important variable operating cost), manufacturers of commercial aircraft will see lower demand for new planes if low jet fuel prices become the long-term norm. The primary factor driving the larger airlines to replace aircraft in their fleets is the lower operating costs due to the much greater fuel efficiency of new models.

And, of course, low oil prices are systematically bad news for oil producers, including the major U.S. companies.

The Good News

Finally, here is the upside of these significant changes in crude oil markets.

Low oil prices are unambiguously good for aggregate global welfare. This includes consumers in the United States, Europe, Japan, and South Korea. And, at least temporarily, OPEC seems to have lost its ability to set a price floor.

Low oil prices mean an increase in consumers’ disposable income, amounting to nearly $2,500 per U.S. household annually, according to Stephen Brown (see below).  If we subtract the income losses to U.S. oil producers, the net gain per U.S. household amounts to a bit more than $800 per year, with gains accruing disproportionately to low-income households.

Turning to the environmental realm, there is also good news, or at least the possibility of good news. An opportunity for new, sensible energy and climate change policies has emerged with these low oil prices.

First, now is the time to reduce – or better yet, phase out – costly and inefficient fuel subsidies, which exist in many parts of the world, particularly in developing countries.

Second, with gasoline prices relatively low – and natural gas supplies holding down electricity prices, at least in the United States – there has never been a better time to introduce progressive climate policies in the form of carbon-pricing, whether via carbon taxes or through carbon cap-and-trade. Unfortunately, none of us should hold our breath waiting for that to happen.


For further reading, I recommend:

Bordoff, Jason, and Akos Losz.  “Oil Shock: Decoding the Causes and Consequences of the 2014 Oil Price Drop.”  Horizons, Spring 2015, Issue No. 3, pp. 190-206.

Brown, Stephen P. A.  “Falling Oil Prices: Implications in the United States.” Resources, Number 189.  Washington:  Resources for the Future, 2015, pp. 40-44.