Ken Caldeira is a climate scientist focusing on the nexus between climate, the carbon cycle, and our energy system. He works at the Carnegie Institution and is a professor in the department of global ecology at Stanford University. He has studied issues such as ocean acidification, intentional intervention in the climate system, mass extinction events in Earth's geologic history, and the scale of change needed to address our current climate/carbon problem. He has participated in the writing of reports for the Intergovernmental Panel for Climate Change and the US government and has provided technical support in the negotiation of international agreements.