Dr. Weitzman was a longtime economics professor at Harvard University before retiring last summer, shortly before being passed over for a Nobel Prize in economics that he was widely expected to win or share. Instead, the honor went to Paul M. Romer and William D. Nordhaus, a climate change specialist who later called Dr. Weitzman “a radically innovative spirit in economics.”
“His work as a theorist on environment, broadly, and on climate change, in particular, was unparalleled, and formed the basis for theoretical and empirical work carried out by legions of economists and other scholars around the world,” said
Robert N. Stavins, the director of Harvard’s environmental economics program.
“If economic theory is about stripping a problem down to its absolute essentials, and from this deriving meaningful insights,” Stavins added by email, “then Weitzman was a master.”
Armed with little more than a legal pad and a No. 2 pencil, Dr. Weitzman delved into issues of biological diversity, unemployment, inflation and bioengineering, often mixing complex mathematical proofs with references to Greek mythology. With literary flair, he dubbed a key component of his climate change analysis the Dismal Theorem, riffing on economics’s nickname as “the dismal science.”
Dr. Weitzman originally specialized in comparative economic systems, focusing on the Soviet Union after teaching himself Russian in college, traveling to Moscow on a Guggenheim Fellowship and partnering with local researchers to write a pair of Russian-language articles. But his path was fundamentally altered when a paper he wrote about the relative advantages of price and quantity controls was rejected, and a reviewer proposed he recast the article to focus on pollution.
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The result, “Prices vs. Quantities” (1974), became “the most frequently cited paper in environmental economics,” according to Stavins, and introduced a “breathtakingly simple” method for comparing those two instruments of economic planning, epitomized by the use of carbon tax and cap-and-trade policies to tackle climate change.
Dr. Weitzman spent much of the next four decades working as an environmental economist, producing insights that included the calculation of green GDP, in which the economy is measured partly by accounting for the harmful effects of pollution and the destruction of natural resources.
When it came to climate change, an issue that he described as the “wicked problem,” he broke from many of his peers to argue that most economic models were probably far too conservative, creating the “illusion of sureness.”
“Everything in climate change is uncertain because we don’t know what these extreme values are,” he said in a video interview for Harvard’s Center for the Environment. “They’re outside the range of most of our models, they’re outside the range of our usual thinking, so that there’s no way we can really, truly pin down the probability of a catastrophe and the magnitude of a catastrophe.”
Dr. Weitzman focused not on likely outcomes but on low-probability, high-impact scenarios known as fat tails. He argued — convincingly — that the worst-case possibilities of a warmer planetary future were so bad, they could not be ignored. A Bloomberg tribute last week dubbed him “the man who got economists to take climate nightmares seriously.”
In 2015, Dr. Weitzman partnered with a former student, Gernot Wagner, to publish “Climate Shock: The Economic Consequences of a Hotter Planet.” The book highlighted some of the risks posed by global warming and explored geoengineering, including proposals to reflect sunlight (known as solar radiation management), as a relatively inexpensive way to offset its effects.
“The world is a messy place,” Dr. Weitzman and Wagner wrote in a 2013 New York Times op-ed. “The scientific method imposes some order, but in the case of climate change, that order is probabilistic. For the sake of science and the planet, we should not become distracted by a false sense of certitude. Imprecise truths are the most inconvenient ones. We know enough to act now. What we don’t know should prompt us to even more decisive action.”
Dr. Weitzman was born Meyer Levinger (or Levenger; his wife said she was unsure of the correct spelling) in Manhattan on April 1, 1942. His mother died when he was an infant. With his father serving in the Army during World War II, Meyer was put into foster care; he was ultimately adopted by two elementary school teachers, who named him Martin Lawrence Weitzman and raised him in the planned community of Levittown, N.Y.
He studied math and physics at Swarthmore College in Pennsylvania, graduating in 1963, and received a master’s degree in statistics and operations research from Stanford the next year, followed by a doctorate in economics from the Massachusetts Institute of Technology in 1967.
Dr. Weitzman taught at Yale and MIT before joining Harvard in 1989. And while he generally distanced himself from politics and the application of his theories, he advised organizations including the World Bank, the International Monetary Fund and the Agency for International Development.
“The theme of his work throughout his entire career is uncertainty,” Wagner said in a phone interview. “How can you minimize being wrong? . . . We have to acknowledge the uncertainties, have to embrace them, and make policy as best we can.”
Dr. Weitzman acquired some mainstream prominence after publishing “The Share Economy” (1984), in which he proposed battling unemployment and inflation through labor market reforms, notably profit-sharing programs linking pay with performance. A New York Times editorial called it the “best idea since Keynes.”
“In Weitzman’s tract lay the intellectual origins of the single most powerful trend in American work: employee ownership,” journalist Michael Lewis wrote in a 2000 article for the Times, citing the rise of stock packages (one way of linking compensation with corporate success) among senior employees and chief executives.
Dr. Weitzman’s marriage to Dorothy Earley ended in divorce, and in 2013 he married Jennifer Brown Baverstam, a translator and piano teacher. In addition to his wife, survivors include a daughter from his first marriage, Rodica Weitzman; four stepchildren, Kristian, Madeleine, Sebastian and Oliver Baverstam; a sister; and two grandchildren.
In the early 1970s, he purchased a marsh island in Gloucester, Mass., where he constructed a cabin and eventually a house, creating an academic refuge where he taught himself Bayesian econometrics and watched as sea levels rose outside his window and around the world.
“I think, alas, that we will keep drifting to higher and higher greenhouse gas concentrations until climate change is perceived as something catastrophic at a grass-roots level,” he told the Times in 2015. “The issue is not whether we will have disastrous effects,” he added, “but when climate change will have disastrous effects.”
Correction: An earlier version of this story incorrectly reported that Dr. Weitzman retired last fall. He retired last July and was honored at a symposium in the fall. The story has been updated.