Diffenbaugh received his Ph.D. in Earth Sciences from the
University of California, Santa Cruz in 2003. His dissertation was entitled “Global and regional controls on Holocene environments”.[5] His dissertation focused on understanding regional
climate change in paleoclimate periods and
in modern periods. His dissertation introduced the hypothesis that as vegetation responds to changes in climate, those changes could impact coastal ocean systems by altering the atmospheric pressure patterns that drive coastal winds.[6]
In 2004, Diffenbaugh began a faculty position at
Purdue University.[1] While at Purdue, he published first results of high-resolution regional climate simulations for large continental areas, including the United States, Europe and India, which enabled analysis of the role of fine-scale climate processes in extreme events.[7][8][9][10] These high-resolution climate model simulations also enabled analyses of potential impacts of climate change on a suite of systems, including premium winegrapes, corn pests, and snowmelt runoff.[11][12][13]
In 2009, Diffenbaugh moved to a faculty position at
Stanford University.[1] He continued his work on the dynamics and impacts of fine-scale climate change,[14] and also began working in the emerging area of “extreme event attribution”.[15] This work culminated in the publication of a new, generalized framework for testing the influence of global warming on individual extreme weather and climate events.[4][16]
The extreme event for which Diffenbaugh is most well known is the
2011-2017 California drought.[3] From 2014-2016, Diffenbaugh's research group published three widely cited papers analyzing the drought and the role of global warming.[17][18][19] These studies analyzed the role of high temperature in amplifying the effects of low precipitation, as well as the role of the
Ridiculously Resilient Ridge, a term coined by Diffenbaugh's then-Ph.D. student
Daniel Swain to describe the large area of persistently high atmospheric pressure that blocked many storms from reaching California for much of the drought.[20]
At Stanford, Diffenbaugh also began collaborations to quantify the economic impacts of
climate change. This work has included quantifying the economic damages associated with different levels of global warming (including the levels identified in the UN
Paris Agreement),[21] as well as the role that global warming has played in shaping economic inequality between countries.[22]
Diffenbaugh has written a number of opinion articles. These include op-eds in
The New York Times about extreme climate events such as the
2011-2017 California drought[30] and
Hurricane Harvey,[31] and the process of climate science.[32] He has also written for the public on the importance of peer review, including a Top 10 list of reviewer comments that Diffenbaugh stated came from papers on which he was the first author.[33]
Diffenbaugh frequently speaks to the public about climate change.[1] In 2011, he was a Google Science Communication Fellow.[34] He was an early adopter of Hangouts On Air, through which he conducted open discussions about climate change with the public.[35][36]
In 2017, Diffenbaugh was the faculty moderator for Stanford University's Three Books Program, in which all incoming first-year undergraduate students are sent three books over the summer, and the authors come to campus for a panel discussion during New Student Orientation.[37] Diffenbaugh selected the theme of “Sustainability and Equity”, and assigned Salvage The Bones by
Jesmyn Ward, Homegoing by
Yaa Gyasi, and The Sixth Extinction by
Elizabeth Kolbert.[38] About choosing the books, Diffenbaugh said, "Once you begin to examine the relationship between people and the environment, it becomes clear that the big global challenges for this generation lie at the intersection of sustainability and equity – the two are inextricably linked."[37] At Stanford, he teaches a course called "The Global Warming Paradox" that examines this challenge.[39]
Personal life
Diffenbaugh discussed his upbringing in a 2017 interview on the science podcast Forecast.[40] Diffenbaugh grew up at Mount Madonna Center, an
intentional community in the
Santa Cruz Mountains of
California that was founded in 1978 by Diffenbaugh's parents and other students of
Baba Hari Dass. He attended Mount Madonna School from kindergarten through high school, graduating in 1992.[40][41]
Diffenbaugh attended college at
Stanford University, where he was a member of the varsity men's volleyball team.[42] After college, he returned to Mount Madonna Center for three years.[40] During that time, he taught high school science and coached volleyball at Mount Madonna School, before entering graduate school at the
University of California, Santa Cruz, where he describes struggling to find a sense of scientific confidence and direction.[40]
Diffenbaugh and his wife Polly Diffenbaugh live on the Stanford campus, and have three children.[3] He is the grandson of computer pioneer
Erwin Tomash,[43] and brother-in-law of novelist
Vanessa Diffenbaugh.
Field, C.B., N.R. Chiariello and N.S. Diffenbaugh, Climate-change impacts on California ecosystems, in E. Zavaletta and H. Mooney, (eds), Ecosystems of California, University of California Press, 1008 pp, 2016.
White, M.A., G.V. Jones and N.S. Diffenbaugh, Climate variability, climate change, and wine production in the western United States, in F.H. Wagner (ed.), Climate Change in Western North America: Evidence and Environmental Effects, University of Utah Press, 288 pp, 2009.