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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Inviting you to a Celebration of the Contributions of Martin Weitzman to Environmental Economics

Even the shortest of short lists of scholars who have made the greatest contributions to environmental economics would include my colleague, Professor Martin L. Weitzman of the Department of Economics at Harvard University.  His seminal contributions are legendary, including within the literatures of efficient policy instrument choice under uncertainty, optimal economic growth, biodiversity, long-term discounting, and the economics of catastrophic climate change.

In a future blog post, I will offer a fuller essay on Martin Weitzman’s great contributions to environmental economics, but today I wish to alert the readers of my blog that we – the Harvard Environmental Economics Program – are holding an important event at Harvard on the occasion of Professor Weitzman’s “retirement” (as if Marty will ever really retire!).  The event, “Frontiers in Environmental Economics and Policy:  A Symposium in Honor of Martin L. Weitzman,” will take place on Thursday, October 11th, 2018, from 3:00 to 5:30 pm (with a reception to follow), at the Harvard Kennedy School’s Nye Conference Room on the 5th floor of the Taubman Building.

The Keynote Speaker will be William D. Nordhaus, Sterling Professor of Economics at Yale University, who will speak on “The Intellectual Footprint of Martin Weitzman in Environmental Economics.”

Following Bill’s keynote address, I will have the privilege of moderating a panel of scholars, who themselves have made important contributions to environmental economics, and who will address various elements of Marty Weitzman’s scholarly work.  The panel will consist of the following distinguished participants (in alphabetical order):

I hope you will be able to join us for this very special afternoon.  The symposium is public, but if you would like to attend, it is necessary that you RSVP at https://heep.hks.harvard.edu/weitzman, or by contacting Casey Billings via email or by phone at 617-384-8415.

Finally, I’m pleased to say that the Harvard Environmental Economics Program will host the day’s events with support from the Harvard University Center for the Environment and the Mossavar-Rahmani Center for Business and Government at Harvard Kennedy School.

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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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