Scientific advances narrow range of scenarios for projected global warming
New climate science insights have enabled researchers to narrow the projected range of warming that would occur for a doubling of carbon dioxide in the atmosphere, which is known as the "equilibrium climate sensitivity" (ECS).
How it works: However, armed with better knowledge of historical climate change, and guided by additional tools, scientists narrowed the "very likely" range of global warming by the end of the century, relative to 1850-1900 levels, to between 2°C and 5°C (3.6°F to 9°F). The likely range is now between 2.5°C and 4°C (4.5°F to 7.2°F).
- This compares to the previous report's range of 1°C to 6°C (1.8°F to 10.8°F), with a "likely" range of 1.5°C to 4.5°C.
- The new very likely range has at least 90% confidence.
- This means we're less likely to get by with low levels of warming by adding more CO2 to the air, but also that higher-end scenarios falling outside the range are more remote possibilities.