Climate Sensitivity: Feedbacks Anyone? #skeptical
A recently published paper by Hansen and Sato (2011), Paleoclimate Implications for Human-Made Climate Change , examines evidence from past climates about the various feedbacks that affect climate sensitivity. A feedback is a mechanism that either amplifies (positive feedback) or dampens (negative) the initial effect. Interest is a feedback on a loan. If there were no feedbacks in the Earth’s climate system, physics tells us climate sensitivity would be 1.2°C for a doubling of CO2 . In reality, a complex array of interacting positive and negative feedbacks come into play. Climate models include “fast feedbacks” like water vapor, clouds, sea ice, and aerosols (reflective particles that hang in the atmosphere), but exclude longer-term “slow feedbacks” like ice sheets (an icy surface reflects more heat than a dark surface) and greenhouse gases (warming releases gases from the...