Tim Barnett: 1938-2022

Geophysicist led first wave of El Niño forecasting, foretold demise of Western reservoirs

Tim Barnett, a research marine geophysicist at Scripps Institution of Oceanography at UC San Diego who made climate models become reliable as predictive tools, died Aug. 12 at his home in San Diego, Calif. He was 83.

Barnett was already established as a pioneer who incorporated mathematics and statistical methodology into seasonal forecasts when in 2008, a prophetic paper he co-authored garnered the attention of international media. The study, bluntly titled “When will Lake Mead go dry?,” predicted a 50 percent chance that Lake Mead, a key source of water for millions of people in the southwestern United States, would be dry by 2021 if the pace of climate change continued and future water usage were not curtailed. That study and a 2009 follow-up paper shocked the public and resource managers in the Southwest alike by providing specific dates when conditions would become dire and predicted specific water shortfall amounts under various scenarios.

Barnett’s death coincides with a summer that has seen the prediction largely borne out as Lake Mead and other Colorado River reservoirs face historic lows.

“Tim was a pioneer in many important aspects of climate research revolving around seasonal forecasting and understanding how climate change is affecting our society,” said Scripps climate scientist David Pierce, who collaborated with Barnett on the Lake Mead projections and other papers documenting the human fingerprint on a changing climate. “Tim had a direct, down-to-Earth way of connecting with people, from his fellow hunters to members of congress to Nobel Prize winners, and was able to convey to a wide audience why climate was important in shaping our economy and lives.”

Well before the Lake Mead paper, however, Barnett had already gained renown as a member of a then-small community of researchers who set about to improve predictions of El Niños, climate events characterized generally by the eastward shifting of a warm pool of equatorial Pacific Ocean water. The research community had been caught off guard when one of the largest El Niño winters in history developed in 1982 and scientists only realized what it was well into the event. 

The unpredicted El Niño caused billions of dollars in damage to coastal communities along the eastern Pacific and the loss of as many as 2,000 lives. In response, government funding was provided to accelerate modeling at Scripps Oceanography’s Climate Research Division and other centers such as Lamont-Doherty Earth Observatory in New York. The effort led to Barnett’s successful prediction of a powerful El Niño in the winter of 1997, garnering widespread media coverage. Forecast abilities in the scientific community have advanced ever since. 

Tim Barnett describes early efforts to predict El Niños using computer models

“Tim was on the forefront in innovating techniques to consider global influences in seasonal climate forecasting,” said Scripps climate scientist and longtime colleague Dan Cayan. “He had a no-nonsense style in zeroing in on important climate puzzles and ways to solve them. And he was masterful in communicating results, including putting research findings and possible policy actions into the hands of key decision makers.”

Barnett played a key role in uncovering and documenting the effects of human-generated greenhouse gases on climate warming. In 2001 he led a team that showed the oceans were warming due to human-caused climate change, a key finding because oceans cover the majority of the earth’s surface and are not subject to urban heat island effects, a confounding influence that was widely debated at the time. In 2008 he zeroed in on the western United States, showing that climate change was already altering the snowpack, temperature, and river runoff in the region.

Barnett was born Sept. 23, 1938 in Huntington Beach, Calif. He attended Pomona College in Claremont, Calif. and received a B.A. in physics and mathematics. He received his PhD in oceanography from Scripps Oceanography in 1966. Barnett completed his thesis on ocean surface wave dynamics working with physicist Klaus Hasselmann, a 2021 Nobel Prize recipient and emeritus professor at the Max-Planck-Institut für Meteorologie in Hamburg, Germany. He worked as manager of the Ocean Physics Department at Westinghouse Electric Corporation in San Diego until 1971 when he returned to Scripps Oceanography as the academic administrator for the North Pacific Experiment (NORPAX). NORPAX studied the interactions of the North Pacific Ocean and the overlying atmosphere on climatic time scales. In 1975 he joined the Scripps Oceanography Climate Research Division.

Tim Barnett (standing, fifth from left) and members of the Climate Research Division, 1985
Tim Barnett (standing, fifth from left) and members of the Climate Research Division, 1985


Barnett investigated myriad elements of climate including the effects of land processes on climate change, and the recognition of greenhouse gas signals (such as sea-level rise). He developed detection methods to identify anthropogenic signals associated with global warming.

“Ongoing changes continue to verify Tim's seminal work to detect and forecast anthropogenic influence as a driver of climate and water resources,” Cayan said.

Barnett testified before the U.S. Congress during his career and served as an advisor to governmental agencies on ocean and climate phenomena. He served on numerous National Academy of Sciences panels including the Climate Research Committee and the U.S. Advisory Panel for the Tropical Ocean/Global Atmosphere program. Barnett was a lead contributor to the first Intergovernmental Panel on Climate Change (IPCC) report issued in 1990 and participated in two subsequent IPCC reports. He was one of many scientists around the world who shared in receiving the Nobel Peace Prize in 2007 for the IPCC’s work in alerting society to the threat of climate change.

Scripps scientist Tim Barnett addresses the media after releasing findings predicting a shortfall of water in Lake Mead, 2008
Tim Barnett addresses the media after releasing Lake Mead forecast, 2008


Barnett received the Sverdrup Gold Medal from the American Meteorological Society in 1993, the highest honor the society can bestow on an oceanographer. In 2013, Britain’s Royal Meteorological Society awarded him its Symons Gold Medal, the society’s premier award. It was the first time in the history of the award that a Scripps Oceanography scientist received the honor. Barnett was also a fellow of the American Geophysical Union and the American Meteorological Society and the author of more than 230 scientific papers.

An avid sport fisherman and hunter, Barnett was often an informal source for journalists seeking information about how El Niño and global warming affected migration patterns of game fish off California.

Barnett is survived by sons Blake Barnett of San Antonio, Texas; Steven Barnett and William Barnett of San Diego, Calif; and seven grandchildren. He is preceded in death by wife Judie, who died in 2020.

Barnett's family plans a private memorial service.

Members of the Scripps Oceanography community and Barnett’s colleagues are invited to add tributes to this notice. Please submit them to scrippsnews@ucsd.edu.




“During my stay at Scripps Institution of Oceanography, Tim Barnet was my PhD student. He worked with me on the development of ocean surface wave dynamics, completing his doctoral thesis in 1967. He became a life-long co-worker and friend. In the 1970s, he participated in the JONSWAP (Joint North Sea Wave Project) on the island of Sylt in Germany that became the basis for ocean forecasting models. We developed several different models, and he took part in various model comparisons and a number of statistical studies on air-sea interactions. However, he not only was a stimulating co-worker, but also a close friend. With him and his family, we undertook many private activities and outings. We have many very fond memories.”

– Klaus Hasselmann, physicist, Max-Planck-Institut für Meteorologie, Hamburg, Germany


"Tim hired me as postdoc in 1996. He was a great scientist and a pioneer in climate research, including seminal work in seasonal prediction and climate change attribution. Tim had a keen sense for the most societally-relevant big climate science problems and the creativity and know-how to solve them. He was consistently an innovator and a strong supporter of promising young scientists in his classic no-nonsense style. I am forever grateful to Tim for his mentorship in my early days at Scripps."

– Alexander Gershunov, climate scientist, Scripps Oceanography


"Our collaboration with Tim and his Scripps colleagues back in 2007 and 2008 was one of the most enjoyable and successful collaborations we've ever had. It was such a treat to come down to Scripps and work on univariate and multivariate detection and attribution issues. I vividly remember the excitement of hanging out in a conference room and planning those papers.

In retrospect, those papers marked a key contribution. They helped to show (convincingly, in my opinion) that human-caused warming was now an active influence on hydroclimate in the western U.S. The final paragraph of the Barnett et al. 2008 Science paper was right on the money:

   'Our results are not good news for those living in the western
   United States. The scenario for how western hydrology will continue
   to change has already been published using one of the models used
   here as well as in other recent studies of western U.S.
   hydrology. It foretells water shortages, lack of
   storage capability to meet seasonally changing river flow, transfers
   of water from agriculture to urban uses, and other critical impacts.
   Because PCM performs so well in replicating the complex signals of
   the last half of the 20th century, we have every reason to believe
   its projections and to act on them in the immediate future.'

One of the things I really appreciated and admired about Tim was his single-minded focus on the science. He did not care about power or influence. He wanted to to do the best-possible science. He wanted to get the science right.

I often thought "What would Tim do?" in particularly thorny political situations. The answer was always clear. He would say: "Screw the politics. Keep doing the science."

So that's what we did.

Tim's D&A work had a 'discernible influence' on my entire scientific career. His early research on the identification of variables with high signal-to-noise ratios (the 1987 Barnett and Schlesinger JGR paper) was particularly influential, and helped to draw attention to 'canaries in the coal-mine' for greenhouse-gas signal identification. Sadly, few folks now involved in D&A are familiar with Tim's early work in detection and attribution.

After the turbulent aftermath of publication of Chapter 8 of the IPCC's 1995 Second Assessment Report, Tim was a good friend to me. It was a really tough time. Having supportive friends like Tim helped me to get through those difficulties."

– Ben Santer, climate scientist, Lawrence Livermore National Laboratory, Livermore, Calif.


"It was with great sadness that I heard the news of Tim’s passing.  He was a giant in his field and played a key role on pushing the hydrologic community to recognize the reality of climate change, and its implications for the hydrology of snow-affected and cold regions.  I had the opportunity to work with Tim on two occasions.

In the early 2000s, Tim had become convinced that the implications of climate change for water in the Western U.S. were underappreciated.  He “sold” to DOE a project to use the NCAR-DOE Parallel Climate Model to shed more light on the topic.  The project he formulated, which came to be called the Accelerated Climate Prediction Initiative, consisted of multiple investigators mostly at Scripps, Pacific Northwest National Laboratory, and the University of Washington.  Tim asked me to put together a statement of work and budget (in fairly short order) to do hydrologic and water management modeling for the major river basins of the West as they would be affected by climate change over the next century.  Not long thereafter, Tim got back to me and said, “the budget’s too high, you can have $X, and modify the statement of work to suit.”  We’d decided to interpret the major rivers of the Western U.S. as the Columbia (Pacific Northwest), Sacramento-San Joaquin (California), and the Colorado.  The easiest thing to do was drop one of them, which ended up being the Colorado (with which we had the least experience).  A few months later, Niklas Christensen walked into my office looking for an MS thesis topic, and I suggested that he take on the Colorado.  As it turned out, his work (which appeared along with a number of other papers in a 2004 special issue of Climatic Change devoted to the ACPI project) received a lot more attention than our other ACPI work.

A year or so after the start of ACPI, Tim called me and said 'I was asked to write a paper for Nature on climate change and snow.  The paper came back from review with lots of nasty comments saying that I didn’t reference this or that Lettenmaier paper.  I think you were the reviewer.'  He went on to suggest 'Why don’t you just take over the paper?'  I told him that I knew nothing about the paper, and for sure hadn’t reviewed it, and it was his paper – but I would be willing to help address the comments (I found out afterwards that the reviewer was my good friend, the late Eric Wood).  In any event, I recruited then-graduate student Jenny Wood (now a professor at Washington State University) to add some context based on her modeling work, like how many people live in snow-affected regions globally, and to produce a map.  The resulting paper, published in 2005, continues to be cited well over 200 times per year 17 years after its publication, and has been used as the justification for many studies, and even NASA mission proposals."

– Dennis Lettenmaier, hydrologist, University of California Los Angeles


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