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Unit 2: Atmosphere // Section 9: Feedbacks in the Atmosphere

Understanding how rising GHG levels may affect Earth's energy balance is complicated because of feedbacks in Earth's climate system. Feedbacks are interactions between climate variables such as temperature, precipitation, and vegetation and elements that control the greenhouse effect, such as clouds and albedo. Positive feedbacks amplify temperature change by making the greenhouse effect stronger or by reducing albedo, so they make the climate system more sensitive to the properties that trigger them. Negative feedbacks have a dampening effect on temperature change, making the climate system less sensitive to the factors that trigger them.

Feedbacks can be very complex processes and may take place over short or long time spans. Important feedbacks in Earth's atmosphere include:

Effects of cirrus and cumulus clouds on Earth's energy balance

Figure 20. Effects of cirrus and cumulus clouds on Earth's energy balance
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Source: © National Aeronautics and Space Administration. Earth Observatory.

Feedbacks cause much of the uncertainty in today's climate change models, and more research is needed to understand how these relationships work. A 2003 National Research Council study called for better measurement of many factors that affect climate feedbacks, including temperature, humidity, the distribution and properties of clouds, the extent of snow cover and sea ice, and atmospheric GHG concentrations (footnote 2).

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