Martin Weitzman’s Contributions to Environmental Economics

Many of the world’s most eminent economists and climate scientists gathered on October 11th, 2018, at Harvard Kennedy School to celebrate and honor the career of Martin L. Weitzman, professor of economics at Harvard University, who is “retiring” following four decades of research and writing which have illuminated thought and policy across a broad range of important realms. During his “retirement,” Marty will serve as a Research Professor in Harvard’s Department of Economics.

The October 11th event, “Frontiers in Environmental Economics and Policy: A Symposium in Honor of Martin L. Weitzman,” which drew about 250 people, was organized and hosted by the Harvard Environmental Economics Program (HEEP), with additional support from the Harvard University Center for the Environment and the Mossavar-Rahmani Center for Business and Government at the Kennedy School.

Having learned so much from Marty Weitzman, including during the 26 years that he and I have been co-hosting the Harvard Seminar in Environmental Economics and Policy, I was delighted to moderate the symposium.  From the earliest days of planning the event until the day of the symposium, my team – Rob Stowe, HEEP Executive Director, Jason Chapman, HEEP Program Manager, and Casey Billings, HEEP Program Coordinator – and I were inspired by the breathtaking contributions Marty has made to the once-emerging and now mature global discipline of environmental economics.

In my blog essay today, I want to provide for those who could not attend a sense of what it was like to be there, and remind those who did attend what transpired.

Introducing Professor William Nordhaus

I began the symposium by introducing our keynote speaker, William D. Nordhaus, who just a few days earlier had been announced as a recipient of this year’s Nobel Prize in Economics for his work on modeling the economics of climate change and related public policies.

The cliche that “our speaker needs no introduction” certainly applied here, and so I was very brief, noting first that for nearly four decades, Bill Nordhaus has written about the economics of the environment.  Building on his background as a macro-economist concerned about economic growth, Bill began to give particular attention to the role of energy generation and use in the 1970s, not long after beginning his academic career.  What is truly remarkable is that it was in the early 1980s that he began working on the economics of global climate change, long before most other economists were even aware of the problem, let alone analyzed it.

Bill has been on the faculty at Yale University since 1967, where he is the Sterling Professor of Economics, and Professor in Yale’s School of Forestry and Environmental Studies.  He is a member of the National Academy of Sciences, a Fellow of the American Academy of Arts and Sciences, a Distinguished Fellow of the American Economic Association, and a Research Associate of the National Bureau of Economic Research.  In addition to his many scholarly achievements, he served as a Member of the President’s Council of Economic Advisers in the Carter administration.

What is particularly striking about Bill Nordhaus’s contributions is that — as long as I can remember — he has made his path-breaking DICE model of global climate change economics accessible to and usable by other researchers around the world.

Keynote Address by Bill Nordhaus

Bill launched his presentation, “The Intellectual Footprint of Martin Weitzman in Environmental Economics,” by stating that Marty “has changed the way we think about economics and the environment.”  He then went on to itemize Weitzman’s impressive body of work, including his series of studies on the share economy; his research on the Soviet Union and central planning; his seminal 1974 paper, “Prices vs. Quantities,” which provided fresh insight on how regulatory policy can best be leveraged to maximize public good; and his work on so-called “fat tails” and the “dismal theorem,” which questioned the value of a standard benefit-cost analysis when conditions could result in catastrophic events, even if the probability of such events is very low.

But Nordhaus devoted much of his talk to highlighting Weitzman’s extraordinary contributions to the field of environmental economics, in particular, the economics of climate change and climate change policy. It was Weitzman’s “revolutionary” series of papers on the ideal measures of national income, Nordhaus stated, that focused early attention on the need to take the harmful impacts of pollution into account when tabulating the gross domestic product (GDP), a concept referred to as “Green GDP.”

“Our output measures do not include pollution,” said Nordhaus. “They include goods like cars and services like concerts and education, but they do not include CO2 that is pumped into the atmosphere.”  He explained that pollution abatement measures are often blamed for causing a drag on the economy, but aren’t credited for the health and welfare benefits they create.

“If our incomes stay the same but we are healthier, and live a year longer or ten years longer, that will not show up in the way we measure things,” Nordhaus remarked. “But we can apply these Weitzman techniques to value improvements in health and happiness.”

“Those who claim that environmental regulations hurt growth are completely wrong, because they are using the wrong yardstick,” Bill continued. “Pollution should be in our measures of national output, but with a negative sign, and if we use green national output as our standard, then environmental and safety regulations have increased true economic growth substantially in recent years…For this important insight we applaud Martin Weitzman, a radically innovative spirit in economics.”

A Panel of Leading Environmental Economists

Following the keynote address by Nordhaus, I welcomed to the stage fellow economists Maureen Cropper, Lawrence Goulder, Michael Greenstone, Charles Kolstad, Richard Newell, Robert Pindyck, and James Stock for a lively panel discussion.  Each of these economists have themselves made important contributions to scholarship and policy in the environmental realm.

To each panelist, I posed a question about a different aspect of Marty Weitzman’s key contributions – ranging from climate change policy to biodiversity and fisheries management.

First, Richard Newell, the President and CEO of Resources for the Future (RFF) and a former student of Weitzman when he studied for his Ph.D. in Public Policy at the Harvard Kennedy School, described Weitzman’s seminal paper, “Prices vs. Quantities”, as a “gift that keeps on giving” for economists and policy makers invested in improving regulatory policy.

Next, Charlie Kolstad, a Senior Fellow at the Stanford Institute for Economic Policy Research, focused on Marty Weitzman’s research on biodiversity, and cited it for its “significance and importance.”

Third up was Larry Goulder, the Shuzo Nishihara Professor of Environmental and Resource Economics at Stanford University and a former colleague of Weitzman in the Harvard Department of Economics.  Larry described the importance of Marty’s work on long-term discounting, and commended his 1998 paper on declining discount rate profiles, noting that it has affected public policies in Denmark, France, and Norway, as well as public discussion in the Netherlands, Sweden, and elsewhere. Larry noted that “it’s very important, because it affects decisions as to how much we should invest in infrastructure, in mitigation, and in other realms.”

Fourth on the panel was Bob Pindyck, the Bank of Tokyo-Mitsubishi Professor of Economics and Finance at the Sloan School of Management at MIT, who is very familiar with Marty Weitzman’s work on fat-tailed distributions, and has contributed to that literature himself.  Bob cited Weitzman’s prescient 2007 paper “Subjective Expectations and Asset-Return Puzzles” for its significant influence upon the later modeling of the economics of catastrophic climate change.

Next was Jim Stock, the Harold Hitchings Burbank Professor of Political Economy at Harvard University.  I asked Jim to comment on the effect of Marty’s work on the policy world.  Jim started by crediting Weitzman for the “tremendous influence” his ideas have had upon the formation of public policy in the United States and around the world, citing the nine-state Regional Greenhouse Gas Initiative (RGGI), and the Clean Power Plan introduced by President Obama in 2015.

Sixth on the panel was Maureen Cropper, Distinguished University Professor and Chair of the Department of Economics at the University of Maryland.  Maureen had kindly agreed to talk about Marty Weitzman’s research and outreach in the realm of fisheries management.  Maureen explained that his modeling work in Iceland and elsewhere had affected thinking and discussion around the world regarding the use of taxes and quotas to regulate fishing industries. “This is another example of the use of a simple model and treatment of uncertainly that really did start a conversation among fisheries economists when it came out,” she said.

Finally Michael Greenstone, the Milton Friedman Professor in Economics at the University of Chicago, agreed to reflect on how Weitzman’s theoretical insights were fundamental as the foundation for sound empirical analysis.  Greenstone noted that Marty’s work “takes something you are kind of confused about, and then after you read it, you can’t understand how in the world you were confused beforehand. It just clarifies things in a way that is really beautiful.”

A Book of Testimonials

Many of those who attended the symposium — and many who were not able to join us — wanted to tell Marty directly how they feel about him and his work.  And so we assembled and presented to Marty a book in which we had compiled 60 testimonial letters, including from some of his admirers who could not be with us at the symposium, such as:  Orley Ashenfelter, Greg Mankiw, Kerry Smith, Bob Solow, Nick Stern, Cass Sunstein, and others.  As I presented Marty with the book of letters, I took a moment to read aloud from just one of the letters from another person who could not be with us:

When I was an undergraduate in the economics department at MIT, you were a bright and rising young star.  Later, as a faculty member, I routinely assigned your papers to my environmental economics students.  Your scholarship and your leadership enriched their experiences — and mine — tremendously.

I will never forget when you announced that you were moving on to Harvard — what a blow! —but the universe has seen fit to bring us together once again.  It is an honor to acknowledge your extraordinary contributions to the field, and to thank you for shining a light for all of us.

                                                      All the best,

                                                             Larry

                                                      Lawrence Bacow, President, Harvard University

More Memories

The book did not end with the testimonial letters.  On a personal note, it has been 26 years since Marty Weitzman and I launched the Harvard Seminar in Environmental Economics and Policy.  Over those 52 semesters, we have hosted a total of 398 seminars!  In the very first semester — the fall of 1992 — the seminar presenters included, among others, in alphabetical order: Bill Nordhaus, Kerry Smith, Bob Solow, Rob Stavins, Kip Viscusi, and Marty Weitzman.

In virtually every one of these 400 seminars, everyone in the seminar room – including me — learned not only from each seminar’s presenter, but from Marty’s concise and relevant questions which would inevitably go directly to the heart of the matter.  So, I was pleased to include in the book copies of all 52 seminar schedules, beginning with the fall of 1992 and culminating with the fall of 2018.  I will not say “concluding” with the fall of 2018, because I trust that my collaboration with Marty, which I have valued highly, will continue.

Marty Weitzman has been a treasure for Harvard and for the global scholarly community.  All of us are confident that his contributions will continue to be forthcoming.

Marty Weitzman Responds

Following the Symposium, Weitzman took several minutes to reflect on his remarkable career, recognizing that while he has pursued projects across multiple disciplines, his research would often hit dead ends.

“I’m drawn to things that are conceptually unclear, where it’s not clear how you want to make your way through this maze,” he said. “It’s difficult to describe a creative process, but I get some sort of an inspiration…Most of the time it’s a waste of time because I can’t formalize it, so I try and try and just nothing comes of it. But occasionally it clicks and since it’s typically in an area that’s been understudied, that’s why it’s so dispersed across different fields.”

Weitzman spoke proudly of his work in environmental economics, stating that he “took a decisive step in that direction a few decades ago…getting into the forefront rather than…following everything that went on.” Yet he admitted that he is not very optimistic about the current pace of efforts to combat the harmful mid- and long-term impacts of global climate change.

“It’s not merely sufficient to cut back on carbon emissions or to stabilize carbon emissions. We’ve more or less done that in the last few years, although it could go either way,” he said. “The stuff that does the damage is the stock of carbon dioxide. To get the stock of carbon dioxide to go down, it has almost nothing to do with stabilizing the flow. You have to get the flow down to net zero. That’s what’s so difficult. And the public does not realize that. Victory on the flow front doesn’t translate into victory on the stock front, and that’s what counts.”

As is typical of his style, Marty did not reveal his future plans, saying only that they remain to be determined.  But certainly all those in attendance at the symposium hope that he will continue contributing to the academic and policy discussions surrounding climate change and other critically important environmental economic issues.

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California’s Crude Oil Production and its Climate Change Policies

California is among the most aggressive jurisdictions in the world in its pursuit of public policies to reduce its emissions of greenhouse gases (GHGs), linked with climate change. At a time when the Trump administration in Washington is working to reverse the Obama administration’s climate policy achievements, California and other sub-national entities are taking the lead in the development and implementation of meaningful domestic policies to mitigate the impact of human activity on the climate.

At the same time, California is a producer of crude oil.  Is this inconsistent, or even counter-productive?  In a recent report, advocates have criticized Governor Jerry Brown, and proposed a ban on crude oil production within the State, in furtherance of California’s climate policies.  The thinking goes, crude oil production leads to environmental impacts, so how can it be allowed?

The logic is flawed, and the prohibition – if adopted – would impose tremendous costs on the State with little or no environmental benefit.  As California has developed its climate policies, the need to balance the benefits of these policies with their economic and human consequences has always been a challenging issue.  Achieving aggressive climate goals will not be cheap, so designing sensible, effective policies is critical.  Simply adopting any and all restrictions that might achieve some emission reductions would unnecessarily raise the human cost of limiting GHG emissions.  This is no doubt obvious to some readers of this blog, but for others, let me explain.

At its heart, the climate problem arises because of CO2 emissions associated with the use of energy and related services.  We heat our homes in the winter and cool them in the summer using electricity and natural gas.  We use gasoline to get to work and take vacations.  As each country or state – including California – tries to reduce its GHG emissions, the policies and regulations adopted to achieve this end nearly always target the activities that lead to GHG emissions – the generation of electricity, the use of transportation, and the heating of living spaces.

The proposed ban on crude oil extraction would flip this on its head, focusing instead on the supply of a fossil fuel.  But the simple reality is that the sources of fossil fuel supply are so ubiquitous that crude oil from other regions of the world will replace supplies from California, if California chose not to supply its own on-going needs.  Oil and gas used to heat homes and to power vehicles comes not only from California, but from most every region of the globe.  Many of these regions have expanding supplies of crude oil due to technological improvements, including the Bakken shale of North Dakota, and vast supplies available with relatively little effort, such as in the Middle East.

Advocates claim that reduction of California crude oil production would reduce global consumption of crude – a claim of questionable validity.  But that is not even the right question.  There are many things that can be done to reduce GHG emissions, and a sensible, affordable, and sustainable policy will be one that achieves reductions at the lowest cost.  Even if restricting California’s oil production might reduce global crude consumption, California would certainly bear all of the economic consequences of this policy, as the state would then rely solely on crude oil imports.

In fact, a restriction on California’s crude production is unlikely to reduce GHG emissions within California. The State’s total GHG emissions are limited by the cap of California’s GHG cap-and-trade system.  The most a restriction on California’s crude production can do is to increase costs, while achieving little or no incremental improvement in GHG emissions.

Moreover, supply-side restrictions can limit technological progress that can have very positive economic and environmental consequences.  The same advocates oppose shale “fracking,” but the innovative combination of hydraulic fracturing and horizontal drilling has led both to tremendous economic benefits by expanding supplies of low-cost domestic energy and reducing energy imports, and to environmental benefits by allowing lower-carbon natural gas to displace higher-carbon coal in the generation of electricity across the United States.

By focusing on policies aimed at achieving the appropriate policy goal of reducing GHG emissions – rather than trying to choose winners and losers among technologies and energy sources used to achieve those goals – California can achieve its climate policy goals in ways that are environmentally effective, economically sensible, and ultimately sustainable.  In my view, Governor Brown merits compliments rather than criticism for California’s progressive environmental and energy policies.

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In the past, I have periodically advised the Western States Petroleum Association (WSPA), although on a very different issue, namely the design of California’s CO2 cap-and-trade system.  That was about two years ago, and neither WSPA nor any of its member companies are aware of my writing this essay.  As always in this blog, I am expressing my personal views, and not speaking on behalf of any of the institutions, organizations, or firms with which I am or have been associated.

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Reflections on Economics and Policy Making in the Environmental Domain

This past week, I was privileged to participate in a workshop, “Climate Science in a Time of Political Disruption,” sponsored by the Harvard Program on Science, Technology and Society.  The workshop began with a keynote address by former U.S. Environmental Protection Agency Administrator Gina McCarthy, now Professor of Practice at the Harvard T. H. Chan School of Public Health.  Following Gina McCarthy’s down-to-earth but quite inspiring remarks (with her usual Yankee humor adding spice to the proceedings), the others on the panel were asked to comment on the topic at hand.  The panelists included Joe Goffman, Executive Director of the Environmental Law Program at Harvard Law School; Peter Huybers, Professor of Earth and Planetary Sciences; Sheila Jasanoff, Pforzheimer Professor of Science and Technology Studies at the Harvard Kennedy School; Lucas Stanczyk, Assistant Professor of Philosophy; and myself.

Given the subject of the workshop, most of the panelists focused their comments on the current political scene and the current U.S. administration’s apparent disdain for climate science.  I took a broader, somewhat historical view, and as the only economist on the panel, I commented on the relationship of economic research to policy making.  I did this via reflections on experiences I’ve had over the past three decades.  I tried to make three points:  first, economic research results can be used as a light bulb or a rock, and either can be effective; second, it is important to move quickly when windows of opportunity open in the policy world to implement research ideas; and third, politics matter, and should not be ignored.

  1. Research Results Can be Used as a Light Bulb or a Rock

I cannot speak for the natural sciences, but it is clearly the case that economic evidence can be used either as a “light bulb” – to illuminate an issue and possibly persuade policy makers of the wisdom of a particular course of action – or as a “rock,” that is, as ammunition to support a policy maker’s predisposed position.  Is this cynical?  I think not, because such economic ammunition can help win a policy battle.  I was just reminded by Paul Krugman in his New York Times column of a somewhat less charitable metaphor, where he characterized some politicians as using economists “the way a drunkard uses a lamppost:  for support, not illumination.”

Related to this reality was a session I chaired in 2001 at the annual meetings of the American Economic Association – a roundtable of former chairs and members of the U.S. Council of Economic Advisers (CEA), including George Eads (Charles River Associates), the late William Niskanen (then of the Cato Institute), William Nordhaus (Yale University), and Joseph Stiglitz (Columbia University).  A repeated theme from this set of economists was the reality that CEA typically had more influence by helping others in the Executive Office of the President in their efforts to stop bad ideas than by itself promoting good ideas.

  1. When Windows of Opportunity Open, Move Quickly

Two examples stand out for me of the importance of moving quickly when windows of opportunity open in the policy world to implement research ideas.  One is the work I carried out in the late 1980s under the sponsorship of the late Republican Senator John Heinz of Pennsylvania and former Democratic Senator Timothy Wirth of Colorado in the form of research that led to a report, “Project 88:  Harnessing Market Forces to Protect the Environment.”  One of the proposals in the report was to address the then politically prominent problem of acid rain with what is now called a cap-and-trade system.  This idea resonated with the incoming administration of President George H. W. Bush, particularly with the Counsel to the President, Boyden Gray.  In parallel with work being carried out by Joe Goffman and Dan Dudek (both then at the Environmental Defense Fund), I followed up the Project 88 report with numerous White House and other Washington meetings (commuting weekly from my Harvard perch), which eventually contributed to the Bush Administration’s proposal (to an initially resistant Democratic Congress) of the Clean Air Act Amendments of 1990, including its path-breaking sulfur dioxide allowance trading program.

The other example I mentioned to highlight the importance of moving quickly when windows of opportunity open in the policy world is associated with the negotiations carried out annually under the United Nations Framework Convention on Climate Change (UNFCCC).  At the seventeenth Conference of the Parties of the UNFCCC in Durban, South Africa, in 2011, the delegates agreed to the “Durban Platform for Enhanced Action,” which broke with nearly twenty years of UNFCCC policy by mandating a new approach in which all countries, not just the richest nations, would participate in addressing the need for greenhouse gas (GHG) emissions reductions.  The key challenge for climate negotiators was how to meet this new mandate while still observing the fundamental UNFCCC principle of “common but differentiated responsibilities,” which had previously been interpreted to mean that rich countries alone would shoulder the burden of reducing emissions.

At the Harvard Project on Climate Agreements, we recognized that negotiators around the world were suddenly open to outside-the-box thinking.  Indeed, in Science magazine, my colleague, Joe Aldy, and I wrote an article, “Climate Negotiators Create an Opportunity for Scholars.”  Over the following months (and years) we worked hard to help key negotiating countries develop a new policy architecture that could meet the challenge before them.  The result was a hybrid approach that combined elements of top-down architecture with a healthy dose of bottom-up “pledge-and-review,” which led eventually, of course, to the Paris Agreement of 2015.

  1. Politics Matter

For the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5), I served as Coordinating Lead Author (with Dr. Zou Ji of China) of the chapter on “International Cooperation:  Agreements and Instruments.”  I was surprised to find that the process was highly politicized – in two distinct ways.  First, whereas I had assumed that the Lead Authors (LAs) serving on our writing team were there only to represent their respective scientific expertise (in economics, legal scholarship, international relations, etc.), some of the LAs seemed to represent the interests of their respective countries.

Second, I was very naive about the final step of the process, when the governments of the world are asked to approve the IPCC’s Summary for Policy Makers line by line.  The controversy associated with our chapter on international climate agreements resulted in that entire section of the SPM being eviscerated of all meaningful substance at the Government Approval Sessions for Working Group III (WG III) in Berlin in April, 2014.  I was disappointed and dismayed by the process and its outcome.

Fortunately, I learned from that experience and my attitude (and behavior) was quite different just six months later, when I found myself in Copenhagen for what was essentially the final stage of the entire five-year enterprise of research, writing, and government approval of the various reports of IPCC AR5, namely the government approval sessions for the Synthesis Report (SYR), which summarizes and synthesizes the key findings from all three Working Group reports.  I had learned my lesson.  Rather than disdaining the politics of the occasion, I embraced it and spent the week in Copenhagen in careful negotiations with the key national governments, the result of which was that all of the essential text on international cooperation and agreements was preserved in the Synthesis Report.

Ironically, by recognizing, accepting, and indeed participating in the fundamentally political aspects of the IPCC government approval process, I was able to keep the report of research from itself being politicized.

Summing Up

So, the three points I made regarding the relationship between economic research and policy making at last week’s Harvard workshop were these:  first, economic research results can be used as a light bulb or a rock, and either or both can be effective; second, it is important to move quickly when windows of opportunity open in the policy world to implement research ideas; and third, politics matter, and should not be ignored.

I left it to others at the workshop – and I leave it to readers of this essay – to judge whether any of this applies more broadly to “Climate Science in a Time of Political Disruption.”

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