Future Climate
past climate | present-day climate variability

How much will the earth warm given projected increases in greenhouse gases over the next century? If the climate responded to such a radiative forcing simply by increasing its temperature to emit an equivalent amount of radiation to space, the answer to this question would be trivial. Unfortunately, the increase in temperature causes changes in the climate system that can significantly affect the earth's radiation budget. Further changes in temperature are then necessary to restore radiative equilibrium. Understanding these processes and how they affect the ultimate response of the climate system to radiative forcing is the goal of our research in future climate.

One process that can affect climate sensitivity is known as water vapor feedback. Because warmer air can hold more moisture, the moisture content of the atmosphere probably increases in most regions when the earth warms due to an increase in greenhouse gases. Since water vapor is itself a greenhouse gas, the earth must warm further to balance this additional radiative forcing. Surface albedo feedback can also affect climate sensitivity. Snow and sea ice extent decrease as the climate warms. Since snow and ice are far more reflective of sunshine than bare earth or open ocean, more sunshine is then absorbed by the warmer planet. This increases the warming still further. Assessing the magnitudes of water vapor and surface albedo feedbacks is an important research activity in our group.

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