Understanding the IPCC: An Important Follow-Up

A week ago, I wrote at this blog about my recent frustrations with the government approval process of one part of the Summary for Policymakers (SPM) of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) Working Group III (WG3) report, namely the section in the Summary for Policymakers (SPM.5.2) on “International Cooperation,” for which I had major responsibility.

In that post, I described how the government approval process, which took place in Berlin in early April, had led to the deletion of a significant fraction of the text of SPM.5.2, not because governments questioned its scientific validity, but because they found various passages to be inconsistent with their respective positions and national interests within the ongoing international climate change negotiations under the United Nations Framework Convention on Climate Change (UNFCCC).  (That post took the form of a letter to the co-chairs of WG3 – Ottmar Edenhofer, Ramon Pichs-Madruga, and Youba Sokona.  They have since sent a thoughtful response and agreed for me to provide a link to their letter here.)

Why a Follow-Up Post?

My first post has been widely reported in the press.  Some of this coverage was accurate and reasonable.  Pilita Clark of the Financial Times, in particular, wrote an excellent article that accurately presented my views and conveyed some additional useful insights.  Other press coverage, however, inaccurately stated or suggested that my critique of the IPCC process was much broader than it was.  This was despite my very careful caveats in the first blog post, in which I tried hard to communicate clearly the limited focus of my critique, namely the effects of the government approval process on one section (SPM.5.2) of the Summary for Policymakers.

Some in the more fringe elements of the press and blogosphere quickly capitalized on the situation by distorting the message of my original post to meet their own objectives – by stating or implying that I found fault with the overall IPCC process and reports themselves, that I have positioned myself as an opponent of the important work of the IPCC, and/or that I am a skeptic of the science of climate change!  Because of these over-the-top distortions, I am writing this second post to place my original critique in the context of the overall IPCC process and of the IPCC’s recent Fifth Assessment Report.

Understanding the IPCC Process and Reports

The central purpose of the IPCC Assessment Reports is to survey and synthesize the best published research on climate change, including its causes, consequences, and potential mitigation.  Each of the last several reports has therefore consisted of three volumes, prepared by separate scientific working groups, which address respectively:  (1) research from the natural sciences on climate change itself — whether, how, and to what extent it is happening; (2) the impacts of climate change on natural systems and on human society — and how society might adapt to climate change; and (3) approaches to the mitigation of climate change, including, importantly, policy options for reducing greenhouse-gas emissions.  The chapter of which I was a Co-Coordinating Lead Author, “International Cooperation:  Agreements and Instruments,” fell into this third volume. (See my previous post for further details.)

Hundreds of the world’s leading scientists conducting research on the various topics addressed by the IPCC’s Assessment Reports spend countless un-compensated hours over several years preparing the reports, motivated only by a commitment to scientific rigor and the desire to better understand climate change and its implications.  A core principle of the IPCC process is that the reports should be “policy-relevant but not policy-prescriptive” and should synthesize the peer-reviewed literature as objectively as possible.

The IPCC’s three-volume reports — including the recent Fifth Assessment Report — largely succeed in accurately and objectively synthesizing the best scientific research. The reports are, as a result, absolutely essential resources for both understanding climate change and formulating responses to it.

In addition to being divided into three volumes along substantive lines, the recent Fifth Assessment Report is presented in three different “packages”:  (1) the full volumes, each of which consist of multiple chapters totaling about 2,000 pages; (2) the Technical Summaries (TS), which condense the full volumes into documents of less than 100 pages each; and (3) the Summary for Policymakers (SPM), which at one-third the length of the TS, was the focus of my previous blog post.

I emphasized in that post that none of the deletions and revisions I described regarding the section on international cooperation in the 33-page SPM had any effects whatsoever on the key, foundational products of five years of work on AR5 WG3:  the Technical Summary (three times the length of the Summary for Policymakers, but no more “technical” than the SPM), and – most important – the 2,000 pages of the 15 underlying chapters, including Chapter 13, “International Cooperation:  Agreements and Instruments” (with 79 pages of text, and 57 pages of references).  Only the SPM is subject to the (line-by-line) government approval process.

Furthermore, even the severe cuts to the section on international cooperation in the SPM – the focus of my concerns – should be understood in context.  The governments never added text to the section; rather they deleted text, because in the line-by-line approval process they could not agree among each other.  As I explained in my previous post, the government representatives were doing their job – looking out for the interests of their respective countries.  Any text that was considered inconsistent with their countries’ interests and positions in multilateral negotiations was treated as unacceptable.

Overall, my serious concerns about the effects of the government approval process on one section of the SPM should be considered in the much larger context of what is an exceptionally valuable scientific resource for those concerned with climate change.

A Word on the Government Approval Process

Notwithstanding the problems and challenges of the government approval process, which I highlighted in my previous post, it is important to note the merits of the process, as well, because there are some distinct advantages of the IPCC being an intergovernmental organization and having some aspect of the Assessment Reports requiring government approval (namely, the SPM).

First, as I emphasized in my previous post, government approval has brought political credibility to the IPCC that it would probably not otherwise enjoy.  Second, this process forces member governments to pay attention to the reports, and agree that a substantial body of research on climate change is valid (which would not be the case with a non-governmental organization). It is hardly trivial that the world’s governments have formally (and unanimously) agreed — through the IPCC process — that climate change is real, caused by human activity, and poses significant threats.

My Bottom Line

In the short term, I am continuing to work within the IPCC, as I currently serve as a lead author of the AR5 Synthesis Report, which brings together the essence of the reports of Working Groups 1, 2, and 3.  That work will be completed in October of this year.

In addition, I hope to work constructively with my colleagues within the IPCC, its member governments, and others to address our shared concerns about the SPM approval process — particularly with regard to policy-relevant material in the third (Working Group III) volume of the assessment reports, and most especially in regard to text on international cooperation, which is so intimately connected with the UN climate negotiations in which those same governments are deeply involved.

I conclude this post with the final paragraph of my previous one, which featured my letter to the IPCC WG3 leadership:  “The mission of the IPCC is important, and the scientific work carried out by the hundreds of lead authors of AR5 Working Group 3 was solid and important, as validated by the Technical Summary and the underlying chapters.  I hope this letter can be constructive and helpful for the future work of the IPCC.”


Is the IPCC Government Approval Process Broken?

Over the past 5 years, I have dedicated an immense amount of time and effort to serving as the Co-Coordinating Lead Author (CLA) of Chapter 13, “International Cooperation:  Agreements and Instruments,” of Working Group III (Mitigation) of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC).  It has been an intense and exceptionally time-consuming process, which recently culminated in a grueling week spent in Berlin, Germany, April 5-13, 2014, at the government approval sessions, in which some 195 country delegations discussed, revised, and ultimately approved (line-by-line) the “Summary for Policymakers” (SPM), which condenses more than 2,000 pages of text from 15 chapters into an SPM document of 33 pages.  Several of the CLAs present with me in Berlin commented that given the nature and outcome of the week, the resulting document should probably be called the Summary by Policymakers, rather than the Summary for Policymakers.

Before returning to the topic of today’s blog entry — the SPM process and outcome — I want to emphasize that the IPCC’s Working Group III “Technical Summary” and the underlying Working Group III report of 15 chapters were completely untouched by the government approval process of the Summary for Policymakers.   So, the crucial IPCC products – the Technical Summary and the 15 chapters of WG 3 – retain their full scientific integrity, and they merit serious public attention.  Now, back to the SPM process and outcome …

The process of the government approval sessions was exceptionally frustrating, and the outcome of that process – the final SPM – was in some regards disappointing.  Two weeks ago, immediately after returning from Berlin, I sent a letter to the Co-Chairs of Working Group III — Ottmar Edenhofer, Ramon Pichs-Madruga, and Youba Sokona — expressing my disappointment with the government approval process and its outcome in regard to the part of the assessment for which I had primary responsibility, SPM.5.2, International Cooperation.  At the time, I did not release my letter publically, because I did not want to get in the way of the important messages that remained in the SPM and were receiving public attention through the Working Group III release.

With two weeks having passed, it is now unlikely that the broader release of my letter will obscure the news surrounding the Working Group III release, and – importantly — it could be constructive to the process going forward, as the IPCC leadership and others think about the path ahead for future climate assessments.  Rather than summarizing or annotating my letter, I believe it makes most sense simply to reproduce it, and let it stand – or fall – as originally written.  It follows below.


From: Stavins, Robert
Sent: Thursday, April 17, 2014 4:06 PM

TO: Ottmar Edenhofer, Co-Chair, Working Group III, AR5, IPCC

        Ramon Pichs-Madruga, Co-Chair, Working Group III, AR5, IPCC

        Youba Sokona, Co-Chair, Working Group III, AR5, IPCC

 CC:  Rajendra Pachauri, Chairman, IPCC

          Jan Minx, Head of Technical Support Unit, Working Group III

 FROM:   Robert Stavins

 SUBJECT:     Thoughts on the Government Approval Process for SPM.5.2 (International Cooperation) of the Summary for Policymakers of Working Group 3, Fifth Assessment Report, Intergovernmental Panel on Climate Change

Dear Ottmar, Ramon, and Youba:

I am writing to you today to express my disappointment and frustration with the process and outcome of the government approval meetings in Berlin this past week, at which the assembled representatives from the world’s governments, considered and, in effect, fundamentally revised or rejected parts of the Summary for Policymakers (SPM) of IPCC Working Group 3 over a period of five long days (and nights).  My focus in this letter is exclusively on one section of the SPM, namely SPM.5.2, International Cooperation.  I am not representing nor referring to any other parts of the SPM.

Also, none of what I have to say should be taken as reflecting negatively on you (the Co-Chairs of Working Group 3), the WG 3 Technical Support Unit (TSU), nor the overall leadership of the IPCC.  On the contrary, I thought that all of you did a remarkable job over the five years of work on AR5, as well as during the week in Berlin.  The problems about which I’m writing arose despite, not because of your excellent leadership and support.

More broadly, the problems I identify in this letter are not a consequence of personal failings of any of the individuals involved.  My intent is not to criticize the country representatives, the IPCC leadership, the TSU, the Lead Authors, or the Coordinating Lead Authors.  The problems I seek to identify are structural, not personal.

Further, as Co-Coordinating Lead Author (CLA) of Chapter 13 (International Cooperation:  Agreements and Instruments) of the underlying report, I had primary responsibility – together with my Co-Coordinating Lead Author, Dr. Zou Ji – for drafting the text for Section SPM.5.2 (International Cooperation) of the SPM, and nothing in this letter should implicate Zou Ji, for whom I have great respect and with whom I have enjoyed working.  He may or may not share any of the views I express below.

Another caveat is that none of the problems I describe in this letter apply to either the Technical Summary nor the underlying Chapter 13.  Indeed, because of the problems with Section SPM.5.2 on international cooperation in the SPM, it is important that interested parties refer instead to the Technical Summary, or better yet, the original Chapter 13.

In this letter, I will not comment on the government review and revision process that affected other parts of the SPM, other than to note that as the week progressed, I was surprised by the degree to which governments felt free to recommend and sometimes insist on detailed changes to the SPM text on purely political, as opposed to scientific bases.

The general motivations for government revisions – from most (but not all) participating delegations – appeared to be quite clear in the plenary sessions. These motivations were made explicit in the “contact groups,” which met behind closed doors in small groups with the lead authors on particularly challenging sections of the SPM. In these contact groups, government representatives worked to suppress text that might jeopardize their negotiating stances in international negotiations under the United Nations Framework Convention on Climate Change (UNFCCC).

I fully understand that the government representatives were seeking to meet their own responsibilities toward their respective governments by upholding their countries’ interests, but in some cases this turned out to be problematic for the scientific integrity of the IPCC Summary for Policymakers.  Such involvement — and sometimes interference — with the scientific process of the IPCC was particularly severe in section SPM.5.2 on international cooperation.  It is to that section of the SPM that I now turn.

In the early morning of Monday, April 7, 2014, a draft of SPM.5.2 was completed and approved by the assembled team of CLAs in Berlin.  The draft, a copy of which is attached as Item A, had been extensively revised over the preceding months in response to comments received from governments around the world (to whom multiple drafts had been sent as part of the normal IPCC process). The draft in Item A was sent to governments on April 7th through the IPCC’s PaperSmart system.

The plenary session of government representatives turned their attention to SPM.5.2 at approximately 10:00 pm on Friday, April 11th.  When it became clear that the country delegates were unwilling to move forward with the consideration of the text in plenary, you established a contact group to work on acceptable text.  You gave the group 2 hours to come up with acceptable text.  That group began its work at approximately 11:00 pm (and continued past 1:00 am on Saturday, April 12th).

The contact group included representatives from of a diverse set of countries, ranging from small to large, and from poor to rich.  Hence, I do not believe that the responsibility for the problems that arose are attributable to any specific country or even set of countries.  On the contrary, nearly all delegates in the meeting demonstrated the same perspective and approach, namely that any text that was considered inconsistent with their interests and positions in multilateral negotiations was treated as unacceptable.  In fact, several (perhaps the majority) of the country representatives in the SPM.5.2 contact group identified themselves as negotiators in the UNFCCC negotiations.  To ask these experienced UNFCCC negotiators to approve text that critically assessed the scholarly literature on which they themselves are the interested parties, created an irreconcilable conflict of interest.  Thus, the country representatives were placed in an awkward and problematic position by the nature of the process.

Over the course of the two hours of the contact group deliberations, it became clear that the only way the assembled government representatives would approve text for SPM.5.2 was essentially to remove all “controversial” text (that is, text that was uncomfortable for any one individual government), which meant deleting almost 75% of the text, including nearly all explications and examples under the bolded headings. In more than one instance, specific examples or sentences were removed at the will of only one or two countries, because under IPCC rules, the dissent of one country is sufficient to grind the entire approval process to a halt unless and until that country can be appeased.

I understand that country representatives were only doing their job, so I do not implicate them personally; however, the process the IPCC followed resulted in a process that built political credibility by sacrificing scientific integrity.  The final version of SPM.5.2, as agreed to by the contact group, and subsequently approved in plenary (at approximately 3:00 am, April 12th), is attached to this letter as Item B.

No institution can be all things for all people, and this includes the IPCC.  In particular, in the case of the IPCC’s review of research findings on international cooperation, there may be an inescapable conflict between scientific integrity and political credibility.  If the IPCC is to continue to survey scholarship on international cooperation in future assessment reports, it should not put country representatives in the uncomfortable and fundamentally untenable position of reviewing text in order to give it their unanimous approval.  Likewise, the IPCC should not ask lead authors to volunteer enormous amounts of their time over multi-year periods to carry out work that will inevitably be rejected by governments in the Summary for Policymakers.

I hope I have made it clear that my purpose is not to condemn the country representatives, the IPCC leadership, the TSU, the Lead Authors, or the Coordinating Lead Authors.  The problem is structural, not personal.  In my view, with the current structure and norms, it will be exceptionally difficult, if not impossible, to produce a scientifically sound and complete version of text for the SPM on international cooperation that can survive the country approval process.

More broadly, I urge the IPCC to direct public attention to the documents produced by the lead authors that were subject to government (and expert) comment, but not subject to government approval. I believe that tremendous public good would arise from publicizing the key findings of the Technical Summary and the individual chapter Executive Summaries, instead of the Summary for Policymakers.  I know that as the leaders of the IPCC, you see it to be your responsibility to convey to the public (and policy makers) the results of the hard scientific work that the hundreds of lead authors put into the report over the past five years, and not simply the constrained version of the Summary for Policymakers produced over the past week.

The mission of the IPCC is important, and the scientific work carried out by the hundreds of lead authors of AR5 Working Group 3 was solid and important, as validated by the Technical Summary and the underlying chapters.  I hope this letter can be constructive and helpful for the future work of the IPCC.

Best wishes,


Robert N. Stavins, Albert Pratt Professor of Business & Government, John F. Kennedy School of Government, Harvard University
Director, Harvard Environmental Economics Program
Director of Graduate Studies, Ph.D. Programs in Public Policy and Political Economy & Government
Co-Chair, Harvard Business School-Kennedy School Joint Degree Programs
Director, Harvard Project on Climate Agreements
Blog: An Economic View of the Environment          SSRN Paper Downloads
Mail: John F. Kennedy School of Government, Harvard University, 79 JFK St., Room L-306, Box 11, Cambridge, MA 02138
Phone: 617-495-1820   E-Mail: robert_stavins@harvard.edu
University Fellow, Resources for the Future Research Associate, National Bureau of Economic Research



Can Countries Cut Carbon Emissions Without Hurting Economic Growth?

In the September 21st issue of the Wall Street Journal, the editors pose the following question: can countries cut carbon emissions without hurting economic growth? In his introductory essay, Michael Totty frames the issues as follows:

“There’s little doubt: Cutting greenhouse gases will be costly. But that leads to two big questions. First, how costly? And second, can nations afford it? As policy makers around the world take action to avoid a predicted climate catastrophe, the debate is turning to the costs of reducing carbon-dioxide emissions. Energy-efficiency measures are often pricey, and alternative energy sources are more expensive than the fossil fuels they replace. A steep price on carbon emissions will ripple through the economy. Does that mean a serious effort to tackle global warming is incompatible with economic growth? Or can we make significant cuts in greenhouse-gas emissions without causing serious damage to the economy?

We put the question to a pair of experts. Robert Stavins, a professor of business and government at Harvard University and director of Harvard’s environmental economics program, says the answer to the second question is yes: Making the necessary cuts need cause little more than a blip in world-wide growth if smart policies are used.

Steven Hayward, a fellow at the American Enterprise Institute for Public Policy Research, says no: Energy use — and the carbon dioxide it emits — is so central to the world’s economy that major cuts can’t be made without significant damage.

Of course, the answers can depend in large part on how “significant cuts” and “serious damage” are defined. Many scientists, the European Parliament and the Waxman-Markey climate legislation approved by the U.S. House of Representatives have set a goal of cutting carbon emissions about 80% by 2050, so that was picked as constituting significant cuts.

As the accompanying essays show, such a definition leaves plenty of room for disagreement.”

I encourage you to read the entire Journal Report on Environment in the Wall Street Journal (there’s an excellent Q&A on carbon offsets by Bob Curran) and to check out my affirmative response, “Yes: The Transition Can be Gradual — and Affordable,” as well as Steven Hayward’s well-articulated negative response, “No: Alternatives are Simply Too Expensive.”

Understandably, the editors wanted to highlight differences between us in order to develop a concise and clear debate. I find it interesting, however, that in an audio interview/debate at the Wall Street Journal web site (Podcast: Crafting a Global Policy), which was by nature more free-wheeling and less limited by space constraints, there is a remarkable amount of agreement between Mr. Hayward and me on a number of key issues.

For now, in today’s post — liberated from space constraints — I want to expand a bit on my WSJ essay, in which I responded, yes, the transition can be gradual and affordable.

Can the nations of the world meaningfully address the threat of global climate change without inflicting unjustifiable damage to their economies? The answer that has emerged with increasing clarity is a resounding “yes.”

Although “The Day After Tomorrow,” the 2004 disaster epic about the greenhouse effect’s apocalyptic consequences, had less scientific basis than “The Wizard of Oz,” scientific reality is disturbing enough. Man-made emissions of greenhouse gases — including carbon dioxide (CO2) from the combustion of fossil fuels — are very likely to change the earth’s climate in ways that most people will regret. World energy trends are unsustainable — environmentally, economically, and socially.

The global recession has slowed emissions growth, but the world is on a path to more than double global atmospheric greenhouse gas (GHG) concentrations to 1,000 parts per million (ppm) in CO2-equivalent terms by the end of the century, resulting in an average global temperature increase of 6 degrees Centigrade. But increased temperatures — which might well be welcome in some places — are only part of the story.

The most important consequences of climate change will be changes in precipitation (causing, for example, 75 to 250 million people in Africa to be exposed to increased water stress due to climate change by 2020, with rain-fed agriculture yields falling by as much as 50%), disappearance of glaciers throughout the world (and decreased snowpack in areas ranging from the western United States to Asia), droughts in mid to low latitudes (with severe effects in Australia), decreased productivity of cereal crops (at lower latitudes, especially in tropical regions), increased sea level, loss of islands and 30% of global coastal wetlands, increased flooding (in all parts of the world, but greatest in Asia), greater storm frequency and intensity (both typhoons and hurricanes), risk of massive species extinction (20 to 30% of all species, including massive coral mortality), and significant spread of infectious disease. On the other hand, climate change will also bring some health benefits to temperate areas, such as fewer deaths from cold exposure. But such benefits will be greatly outweighed by negative health effects of rising temperatures (cardo-respiratory, diarrhoeal, and infectious diseases, and increased morbidity and mortality from heat waves, floods, and droughts), especially in developing countries.

These impacts will have severe economic, social, and political consequences for countries worldwide, ranging from malnutrition and mass migration (hundreds of millions of people displaced) to national security threats. Bottom-line, comprehensive estimates of economic impacts of unrestrained climate change vary, with most falling in the range of 2 to 5% of world GDP per year by the middle of the century. The best estimates of marginal damages of emissions (again, by mid-century) are in the range of $100 to $175 per ton of CO2 (in today’s dollars).

The world is already experiencing the adverse effects of increasing concentrations of GHGs in the atmosphere, with concentrations already about 60% above pre-industrial levels, greatly exceeding the natural range over the past 600,000 years. Just one example: the Greenland ice sheet has been losing mass at a rate of 179 billion tons per year since 2003.

To have a coin toss’s 50-50 chance of keeping temperature increases below 2 degrees Centigrade — the level at which the worst consequences of climate change can be avoided — it will be necessary to stabilize atmospheric concentrations at 450 ppm. (Even this would result in significant sea-level rise, species loss, and increased frequency of extreme weather, according to the U.N. Intergovernmental Panel on Climate Change.) Consistent with the 450 ppm goal is a long-range target of cutting U.S. emissions 80% below 2005 levels by 2050, which happens to be the target of legislation passed earlier this year by the U.S. House of Representatives, H.R. 2454, the so-called Waxman-Markey bill.

Now, to the heart of the WSJ question: will a serious effort to tackle global warming is incompatible with economic growth? My response was and is that the nations of the world do not have to wreck their economies to avert the crisis. If appropriate and intelligent policies are employed, the job can be done at reasonable and acceptable cost.

Critics argue that the Waxman-Markey legislation — to cut U.S. emissions 80% below 2005 levels by 2050 — will mean big, disruptive changes to our infrastructure and untold economic damage. But they make a couple of basic errors. For one thing, they seem to think we’d have to replace the entire infrastructure quickly, paying trillions of dollars to shift to cleaner power. They also seem to assume that we have to choose between much more expensive energy and no energy at all.

The move to greener power doesn’t have to be completed immediately, and it doesn’t have to be painful. The right transition plan will increase consumers’ bills gradually and modestly, and allow companies to make gradual, well-timed moves.

How would this work? One way is via a combination of national and multinational cap-and-trade systems. Companies around the world would be issued rights by their governments to produce carbon, which they could buy and sell on an open market. If they wanted to produce more carbon, they could buy another company’s rights. If they produced less carbon than they needed, they could sell their extra rights. What’s more, companies could earn more rights by creating appropriate “offsets” that mitigated their carbon use, such as planting forests. Nations could add carbon taxes to the mix.

The effect would be to send price signals through the market — making use of less carbon-intensive fuels more cost-competitive, providing incentives for energy efficiency and stimulating climate-friendly technological change, such as methods of capturing and storing carbon, as well as safe nuclear power.


Julian Puckett

Robert Stavins

More Efficient

True, in the short term changing the energy mix will come at some cost, but this will hardly stop economic growth. As economies have grown and matured, they have become more adept at squeezing more economic activity out of each unit of energy they generate and consume. Consider this: From 1990 to 2007, while world emissions rose 38%, world economic growth soared 75% — emissions per unit of economic activity fell by more than 20%.

Critics argue we can’t possibly increase efficiency enough to hit the 80% goal. In a very limited sense, that’s true. Efficiency improvements alone, like the ones that propelled us forward in the past, won’t get us where we need to go by 2050. But this plan doesn’t rely solely on boosting efficiency. It brings together a host of other changes, such as moving toward greener power sources. What’s more, making gradual changes means we don’t have to scrap still-productive power plants, but rather begin to move new investment in the right direction.

As for how much this will cost, the best economic analyses — including studies from the U.S. Congressional Budget Office and the U.S. Energy Information Administration — say such a policy in the U.S. could cost considerably less than 1% of gross domestic product per year in the long term, or up to $175 per household in 2020. (As the Obama administration is fond of saying, that’s about the cost of one postage stamp per household per day.)

In the end, we would be delaying 2050’s expected economic output by no more than a few months. And bear in mind that previous environmental actions, such as attacking smog-forming air pollution and cutting acid rain, have consistently turned out to be much cheaper than predicted.

The best economic experts have validated the wisdom of adopting climate policies: from Yale’s William Nordhaus, who has supported moderate carbon taxes to cut emissions as an “insurance policy” against the most serious consequences of climate change, to MIT’s Richard Schmalensee and Columbia’s Glenn Hubbard, who have endorsed the climate policy recommendations of the bipartisan National Commission on Energy Policy, to Harvard’s Martin Weitzman, who has argued for much more aggressive policies because of the risk of particularly catastrophic outcomes. And a diverse set of CEOs, including the heads of some of the largest U.S. corporations, acting as part of the U.S. Climate Action Partnership, have called on the government “to quickly enact strong national legislation to require significant reductions of greenhouse gas emissions.”

Critics are wary of raising energy prices, arguing that no nations have grown wealthy with expensive power. But historically, it is the scarcity and cost of energy that have prompted technological changes as well as the use of new forms of power. What’s more, critics challenge the price estimates the experts have set out. They say that the predictions depend on extensive — and unrealistic — cooperation among nations. In particular, they say, developing nations won’t sign onto plans for curbing emissions, for fear of losing their economic momentum.

Indeed, we do need a sensible international arrangement in place to achieve low costs, and the economic pain will be much greater if we don’t set up an international carbon market. But it can be done. Many nations have already initiated such emissions-control policies. And the world can be brought together in a meaningful, long-term arrangement that is scientifically sound, economically rational and politically pragmatic.

Road to Cooperation

Because the benefits of any single nation taking action to address global climate change are spread worldwide, unlike the costs, it may never be in the self-interest of a single country to take unilateral action. This is the nature of a global commons problem. For this reason, international cooperation is required; this is the point of climate negotiations among some 190 countries, which will continue in Copenhagen this December. It is also the motivation for the U.S. administration’s Major Economies Forum, which brings together the 17 largest economies, accounting for 80% of GHG emissions.

Europe has already put significant climate policy in place, and Australia, New Zealand, and Japan are moving to have their policies in place within a year. But without evidence of serious action by the U.S., there will be no meaningful future international agreement, and certainly not one that includes the key, rapidly-growing developing countries — Brazil, China, India, Indonesia, Mexico, South Africa, and South Korea. U.S. policy developments can and should move in parallel with international negotiations.

Understandably, developing countries have a very different perspective than the currently industrialized world regarding climate policy. After all, the vast majority of the accumulated stock of man-made greenhouse gases in the atmosphere is due to economic activity in the richer countries over the past century and more. But the share of global emissions attributable to developing countries is significant and growing rapidly. China surpassed the United States as the world’s largest CO2 emitter in 2006. And developing countries are likely to account for more than half of global emissions by the year 2020, if not before. China, Korea, and others are beginning to take action.

Most important, all of the key countries of the world can be brought together in a meaningful and pragmatic arrangement. Such a post-Kyoto international agreement can expand the scope of action to include key developing countries, but with targets linked via an appropriate formula with economic growth, so that emissions can be reduced around the world, while emissions (and job) leakage from the industrialized to the developing world is avoided, and economic growth continues in all parts of the world.

Reducing Costs

The longer we put off serious action, the more aggressive our future efforts will need to be, as greenhouse gases and carbon-spewing capital assets continue to accumulate. Plants built today will determine emissions for a generation. In the steel sector — where plant lifetimes typically exceed 25 years — more than half of all plants in the world are now less than 10 years old. The picture is similar in the cement industry, as well as more broadly throughout the economy. For every year of delay before moving to a sustainable emissions path, the global cost of taking necessary actions increases by hundreds of billions of dollars.

Critics argue that we can afford to wait because the world of tomorrow will be wealthier and better able to absorb the costs. But acting sooner, such as by adopting the emission caps proposed in the U.S. House legislation, will lower the ultimate costs of achieving the target, because there will be more time allowed for gradual transition — which is what keeps costs down. Perhaps most important, the costs of failing to take action — the damages of climate change — would be substantially greater.

Getting serious about climate change won’t be free, and it won’t be easy. But if state-of-the-science predictions about the consequences of continued delay are correct, the time has come for sensible and meaningful action.