You may remember Ehrlich as the author of the hysterically alarmist, now totally discredited  1968 best-seller "The Population Bomb," which called for the U.S. government to take "immediate action" to halt population growth, in order to avert mass death by starvation in the 1970s.
Dr. Schneider wrote books on the effects of climate change on areas as diverse as politics and wildlife. He advised the administration of every president from Richard M. Nixon to Barack Obama and was part of a United Nations panel on climate change that shared the 2007 Nobel Peace Prize with former Vice President Al Gore.
In a statement, Mr. Gore called Dr. Schneider "a prolific researcher and author, co-founder of the journal Climatic Change and a wonderful communicator" who greatly contributed "to the advancement of climate science."
In an interview on Monday, the biologist and population expert Paul R. Ehrlich said, "I don't think anybody has worked harder and longer to educate the public on climate issues in particular and science issues in general."