Updated

Ralph J. Cicerone, president emeritus of the National Academy of Sciences and a renowned authority on atmospheric chemistry and climate change, has died. He was 73.

William Kearney, director of media relations for the Washington, D.C.-based National Academies of Sciences, Engineering, and Medicine, said Cicerone died unexpectedly at his home in Short Hills, New Jersey, on Saturday.

Cicerone was the 21st president of the National Academy of Sciences from 2005 until this June. He balanced advocacy for independent scientific advice with maintaining a dialogue with politicians and policymakers on major scientific issues.

A leading atmospheric scientist, his research helped shape environmental policy and science nationally and internationally.

Cicerone's death removes a "great leader" from "the forefront of the scientific issues that matter most to the future well-being of society," said Marcia McNutt, Cicerone's successor as president at the National Academy of Sciences.

"Ralph Cicerone was a model for all of us of not only doing what counts, but doing it with honesty, integrity, and deep passion," she said.

Among his achievements were the restoration and renovation of the National Academy of Sciences building on the National Mall, the creation of a $500 million Gulf research program following the 2010 Deepwater Horizon oil spill, two visits by President Barack Obama to NAS, and a several influential studies on global climate change.

Before becoming president of NAS, Cicerone served as chancellor of the University of California, Irvine, from 1998 to 2005.

He is survived by his wife, Carol M. Cicerone, their daughter, and two grandchildren.

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Associated Press writer Janet McMillan in Philadelphia contributed to this report.