Tim Barnett obtained his Ph.D. in Physical Oceanography from the Scripps Institution of Oceanography (SIO) in 1966. He was appointed to his present rank of Scripps Institution Research Marine Physicist in 1971, and he maintains an active research program in climate prediction and diagnosis, with emphasis on global climate dynamics and ocean/atmospheric coupling.

Barnett was one of the initiators of TOGA, a U.S. national program in tropical ocean/atmosphere climate research. As organizer and lead participant of the Experimental Climate Forecast Center, he has developed and implemented statistical climate prediction models for the U.S. and Eurasia. He is an expert on Global Warming detection and El Niño prediction.

Barnett's public service activities include advising a number of government organizations (NOAA, DOE, NASA, and EPA) on climate research and remote sensing, and JPL on satellite measurements of the sea surface temperature and sensors for remote determination of atmospheric water content. He has served as a member of the Committee on Climate Change in the Ocean, and as a member of the Joint Scientific Committee of the World Climate Research Programme.

Barnett is a Fellow of the American Meteorological Society (AMS), and he was elected to a three-year term as an AMS Councilor. In 1991, he received a Special Creativity Award from the National Science Foundation. His many honors and awards also include the Sverdrup Gold Medal, the highest honor the American Meteorological Society can bestow on an oceanographer, and Fellow of the American Geophysical Union.