Ken Caldeira is a scientist who works at the Carnegie Institution for Science's Department of Global Ecology. He researches ocean acidification, climate effects of trees, intentional climate modification, and interactions in the global carbon/climate system.

Caldeira's work was featured in a November 2006 article in The New Yorker, entitled "The Darkening Sea." In 2007, he contributed two op-ed pieces on the subject of global warming to The New York Times. He was named a "Hero Scientist of 2008" by New Scientist magazine.

In the 1980s, Caldeira worked as a software developer. He received his Ph.D in Atmospheric Sciences in 1991 from the New York University Department of Applied Science. From 1991 to 1993, Caldeira worked at Penn State University as a post-doctoral researcher. He then worked as an Environmental Scientist and Physicist at Lawrence Livermore National Laboratory until 2005, when he began his current position at the Carnegie Institution Department of Global Ecology.