Climate sensitivity

Definition

Climate sensitivity is a measure of how much the Earth's average temperature will increase in response to a doubling of atmospheric carbon dioxide (CO2) concentrations. It is a crucial concept in understanding the potential impacts of climate change, as it helps estimate future temperature changes based on current and projected levels of greenhouse gases, radiative forcing, and various climate feedback mechanisms.

5 Must Know Facts For Your Next Test

1. Climate sensitivity estimates typically range from 1.5°C to 4.5°C for a doubling of CO2 concentrations, reflecting varying degrees of climate feedbacks and responses.
2. Higher climate sensitivity suggests that the Earth is more responsive to increases in greenhouse gas concentrations, which implies more severe impacts from climate change.
3. Climate models play a crucial role in estimating climate sensitivity by simulating different scenarios of greenhouse gas emissions and their effects on temperature.
4. Understanding climate sensitivity is essential for developing effective climate policies aimed at reducing emissions and limiting global temperature rise.
5. The concept of transient climate response (TCR) is related to climate sensitivity and describes the expected warming at the time CO2 concentrations double, accounting for some feedback processes.

Review Questions

• How does climate sensitivity influence predictions made by climate models regarding future temperature changes?
  • Climate sensitivity directly impacts the output of climate models by determining how much warming can be expected from increased greenhouse gas concentrations. Models that incorporate higher climate sensitivity indicate greater temperature increases for a given amount of radiative forcing. This relationship helps scientists and policymakers understand potential future scenarios, allowing them to plan for impacts related to varying levels of warming.
• Discuss the implications of different estimates of climate sensitivity on global warming potential and policy-making decisions.
  • Differences in climate sensitivity estimates can lead to significant variations in projections of future warming and the urgency with which action needs to be taken. Higher estimates suggest that even moderate increases in greenhouse gases could lead to substantial warming, necessitating stricter policies on emissions reductions. Conversely, lower estimates may imply that current policies could suffice, potentially slowing down the pace of necessary action against climate change.
• Evaluate how feedback mechanisms contribute to the understanding of climate sensitivity and influence long-term climate projections.
  • Feedback mechanisms are critical in shaping our understanding of climate sensitivity because they can either amplify or mitigate temperature changes resulting from increased greenhouse gas concentrations. For instance, as polar ice melts, less sunlight is reflected away from Earth, leading to further warming—this positive feedback increases climate sensitivity. Conversely, certain cloud formations may reflect sunlight, providing a negative feedback. Evaluating these complex interactions allows scientists to create more accurate long-term climate projections and assess potential outcomes of different emission pathways.

Related terms

radiative forcing: The difference in energy absorbed by the Earth and energy radiated back to space, which drives changes in climate. Positive radiative forcing leads to warming, while negative radiative forcing leads to cooling.

greenhouse gases: Gases in the Earth's atmosphere, such as CO2, methane (CH4), and nitrous oxide (N2O), that trap heat and contribute to the greenhouse effect, leading to an increase in global temperatures.

feedback mechanisms: Processes that can either amplify or dampen the effects of climate change. For example, melting ice reduces reflectivity (albedo), leading to more heat absorption and further warming.