Climate sensitivity
Topic: Climate Change: Causes, Evidence and the Global Response · NCERT: Class 11, Ch 11 "World Climate and Climate Change"
Meaning
Climate sensitivity is the amount the Earth would eventually warm if CO2 in the air doubled from its level before industry. Before industry, CO2 was 280 ppm (parts per million), so doubling means about 560 ppm. Scientists use this number to compare climate models and predict future warming. IPCC AR6 (the Intergovernmental Panel on Climate Change's Sixth Assessment Report) gives a best estimate of 3 °C, with a likely range of 2.5–4 °C. The higher the sensitivity, the more dangerous each tonne of emissions is.
Example
CO2 reached about 424 ppm in 2024 and rises about 2.3–2.5 ppm a year. That is already about halfway from 280 ppm to a doubling. If doubling is reached, the best estimate means about 3 °C of eventual warming, double the Paris Agreement's 1.5 °C aim.
Don't confuse with
- Global warming potential (GWP): compares how much heat a gas traps over 100 years with the same mass of CO2. Climate sensitivity measures how much the whole planet warms.
Related concepts
- Greenhouse effect
- Greenhouse gases
- Global warming potential
- Methane
- Nitrous oxide
- Chlorofluorocarbons
- Tropospheric ozone
- Carbon sink
- Carbon budget