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.

The Future Role of Economics in the IPCC

Despite attacks from “climate skeptics” and other opponents of action on climate change, as well as its own missteps, the Intergovernmental Panel on Climate Change (IPCC) is broadly viewed as the world’s most legitimate scientific body that periodically assesses the economics of climate change for policy audiences.  But growing inefficiencies and other limitations have made the IPCC an increasingly problematic forum for qualified scholars.  This has been particularly true with regard to expertise from economics.

In an article that has appeared in the journal, Climate Change Economics, “Reforming the IPCC’s Assessment of Climate Change Economics,” my colleagues and I draw on our personal experiences writing the most recent IPCC report to identify some of the main problems faced by this institution and to propose some possible solutions.  My co-authors are, in alphabetical order:  Gabriel Chan (University of Minnesota), Carlo Carraro (Ca’ Foscari University of Venice), Ottmar Edenhofer (Technische Universität Berlin), and Charles Kolstad (Stanford University).

Background and Context

The IPCC was established in 1988 by the World Meteorological Organization and the United Nations Environment Program to assess and synthesize scientific research on climate change, its impacts, and response options. The IPCC is governed by its Plenary (composed of representatives of member governments), Bureau, Executive Committee, and Secretariat, which have distinct roles to provide oversight, develop procedures, and facilitate operation.

Coverage of the scientific literature is divided into three Working Groups that respectively assess climate change science, impacts and adaptation, and mitigation. Authors are nominated by national governments, and selected by the IPCC Bureau.  Authors serve as Coordinating Lead Authors (CLAs), with responsibility for leading the writing of a chapter, or as Lead Authors (LAs), who serve on a chapter team and participate in the writing process.  CLAs and LAs participate in numerous meetings held at diverse locations around the world.  Other experts serve as Contributing Authors (CAs), but the process for nominating these contributors is less formal, and the CAs typically do not participate in meetings and deliberations.

The assessment cycle for each round of the IPCC begins with a scoping process, with government representatives, together with a large group of scholars and other interested parties, drafting outlines of each chapter of the IPCC. Following the scoping process, the IPCC Plenary approves the outlines, sometimes after some modification.

CLAs and LAs are then nominated and subsequently approved by the IPCC Bureau.  CLAs and LAs serve as volunteer labor (although some have their travel expenses reimbursed).  In the Fifth Assessment Report Working Group III process, Lead Author Meetings (LAMs) were convened four times from July, 2011, to July, 2013.  These meetings took place in Changwon, Korea; Wellington, New Zealand; Vigo, Spain; and Addis Ababa, Ethiopia.  Over the course of the LAMs, CLAs led their chapter teams to review relevant literature and prepare chapter text, tables, and figures.

At three points during this process, external Expert Reviewers and government representatives submit detailed comments on subsequent draft. These comments, numbering in the many thousands in AR5, are made public following the assessment cycle, and, are checked by appointed Review Editors, who confirm that authors have replied adequately to comments. After four drafting rounds, the Working Group reports are preliminarily finalized.

Towards the end of the assessment cycles, authors of each Working Group, primarily CLAs, engage in writing two summary documents for each report, a Technical Summary (TS) and a Summary for Policymakers (SPM).   The Summary for Policymakers is subject to line-by-line approval by the IPCC Plenary (that is, the governments).  By the way, in case you’re interested, I have written about these government approval processes at length in previous essays at this blog:  Is the IPCC Government Approval Process Broken? (April 25, 2014); Understanding the IPCC: An Important Follow-Up (May 3, 2014); and The Final Stage of IPCC AR5 – Last Week’s Outcome in Copenhagen (November 4, 2014).

Finally, concurrent with much of the chapter-drafting process, a subset of CLAs and LAs from all three Working Groups convene to draft a Synthesis Report (SYR) and its own Summary for Policymakers.

I’m exhausted, just having written that summary of the multi-year process in which we were engaged in the IPCC’s Fifth Assessment Report.

Categories of Key Reforms

I hope you’ll turn to our article in Climate Change Economics to read about the procedural and substantive reforms we propose.  So, here I’ll provide just a list as a guide to what you can find in the article.

We propose four potential procedural reforms that could lower the cost for volunteering as an IPCC author:

  • Improving interactions between governments and academics
  • Making IPCC operations more efficient
  • Clarifying and strengthening conflict of interest rules
  • Expanding outreach

In addition, we propose three reforms to the IPCC’s substantive coverage to clarify the IPCC’s role and to make participation as an author more intellectually rewarding:

  • Complementing the IPCC with other initiatives
  • Improving the integration of economics with other disciplines
  • Providing complete data for policymakers to make decisions

Looking Forward

My co-authors and I all found that working for the IPCC was at times enormously frustrating. As an IPCC author, particularly as a CLA, scholars can at times feel as if they are inside a political process, forced to respond to critical government comments based on political sensitivity, and even directly negotiating text with professional climate negotiators during the SPM Approval Sessions.

Despite such distractions and frustrations, however, the group of us believe that the IPCC remains a critical institution for the communication of scholarly knowledge about climate change. Engaging governments in often detailed deliberations over climate science, economics, and policy helps build a knowledge base that is broadly based. And the process of consensus-building around the SPM and the work of the underlying chapters play key motivating roles in driving international climate negotiations under the United Nations Framework Convention on Climate Change (UNFCCC).

Going forward, the greatest risk is that scholars with sound and balanced understanding of the relevant literature may be deterred from participating as IPCC authors, and thereby surrender the process to quasi-academics with political motivations.  The potential harm to the policy process (and the reputation of academia) would be very great.

To prevent this from happening, the IPCC needs to reform its operational procedures and substantive scope so that qualified scholars perceive the time investment as authors to be worthwhile. At the same time, scholars of climate change economics should not dismiss the opportunity to provide a significant public service by volunteering for the IPCC in its future assessments.

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.