Global Climate Projections

The United Nations Intergovernmental Panel on Climate Change (IPCC) released the Summary for Policymakers (SPM) of the Working Group I contribution to the Sixth Assessment Report (AR6) "Climate Change 2021: The Physical Science Basis" on 9 August 2021. A new set of 5 scenarios taking into consideration different trends in greenhouse gas concentrations is employed in AR6 to generate climate projections for the 21st century.

SSP3-7.0 and SSP5-8.5: High and very high greenhouse gas emissions, carbon dioxide emissions roughly double from current levels by 2100 and 2050 respectively.
SSP2-4.5: Intermediate greenhouse gas emissions, carbon dioxide emissions remaining around current levels until the middle of the century.
SSP1-1.9 and SSP1-2.6: Very low and low greenhouse gas emissions, carbon dioxide emissions decline to net zero around or after 2050, followed by varying levels of net negative carbon emissions.

It is important to note that climate projection is not weather or seasonal forecast. It aims at describing the plausible changes in future climate from a long-term perspective under prescribed greenhouse gas concentrations rather than depicting the "day-to-day" or "year-to-year" weather fluctuation. Climate projections will vary according to different emissions scenarios. Besides, disparity in climate models' ability in simulating physical processes will also introduce uncertainties to climate projections. The global climate projections reported in IPCC AR6 are summarized below. Further details are available here.

Temperature

Precipitation

Mean sea level

Extreme weather events

Ice and snow

Tropical cyclones