Question

What was the IPCC AR5 estimate of the range of equilibrium climate sensitivity?

a) 1-2°C.
b) 2-4°C.
c) 4-6°C.
d) 6-8°C.

Answer 1

The IPCC AR5 estimates the range of equilibrium climate sensitivity to be between 1.5°C and 4.5°C, with a climate sensitivity parameter of 0.8°C per W/m².

Step-by-step explanation:

The Intergovernmental Panel on Climate Change (IPCC) Assessment Report 5 (AR5) provided estimates for equilibrium climate sensitivity, which is a measure of how much the Earth's average temperature is expected to increase if the concentration of carbon dioxide (CO2) in the atmosphere doubles compared to pre-industrial levels. According to the IPCC AR5, the range of equilibrium climate sensitivity is likely to be between 1.5°C and 4.5°C. Therefore, among the given options, the correct answer would be b) 2-4°C. This estimate considers the climate sensitivity parameter defined as the amount of warming expected for a given amount of radiative forcing, which AR5 puts at 0.8°C per W/m² of radiative forcing.