Climate Sensitivity and Feedbacks
Climate sensitivity refers to how much the Earth’s average temperature will increase in response to a doubling of atmospheric carbon dioxide. Feedbacks are processes that can amplify or dampen this temperature change, such as changes in water vapor, cloud cover, or ice melt. Together, climate sensitivity and feedbacks determine the extent and pace of global warming, making them crucial for predicting future climate impacts.
Climate Sensitivity and Feedbacks
Climate sensitivity refers to how much the Earth’s average temperature will increase in response to a doubling of atmospheric carbon dioxide. Feedbacks are processes that can amplify or dampen this temperature change, such as changes in water vapor, cloud cover, or ice melt. Together, climate sensitivity and feedbacks determine the extent and pace of global warming, making them crucial for predicting future climate impacts.
💡 Key Takeaways
- Define climate sensitivity and explain what a doubling of atmospheric CO2 implies for Earth's average temperature.
- Identify key feedbacks—water vapor, clouds, and ice-albedo—and whether they tend to amplify or dampen warming.
- Differentiate between positive and negative feedbacks and how they shape the overall climate response to increased CO2.
- Understand why estimates of climate sensitivity vary and what factors contribute to uncertainties in projections.
❓ Frequently Asked Questions
What is climate sensitivity?
Climate sensitivity measures how much Earth’s average temperature would eventually rise if atmospheric CO2 were doubled. It reflects the balance of warming and cooling processes and is typically expressed as the equilibrium global temperature increase (roughly 1.5–4.5°C).
What are climate feedbacks?
Feedbacks are processes that change the size of the initial temperature response. They can amplify warming (positive feedbacks) or dampen it (negative feedbacks). Examples include water vapor, clouds, and changes in ice cover.
Why do water vapor and clouds matter for climate sensitivity?
Water vapor increases with warming and amplifies greenhouse warming (positive feedback). Clouds have complex effects: they can reflect sunlight (cooling) or trap heat (warming), and their net impact remains a major source of uncertainty.
Why is there uncertainty in estimating climate sensitivity?
Uncertainty mainly comes from how feedbacks, especially clouds, respond across different timescales and regions. Different models and observations yield a range of sensitivity estimates.