Scientific advances narrow range of scenarios for projected global warming

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.

Go deeper: Sweeping UN report finds effects of climate change even more severe than we thought