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climate change

Global Climate Projections


To make climate projection, four scenarios of greenhouse gas concentration are employed in IPCC AR5, which are RCP2.6 (low), RCP4.5 (medium-low), RCP6.0 (medium-high) and RCP8.5 (high) in the order of increasing concentration. Description of these scenarios can be found in the webpage sedac.ipcc-data.org/ddc/ar5_scenario_process/RCPs.html. Based on these scenarios, different climate centres and research institutes used computer models of various degree of complexity to project future global climate.

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 concentration scenarios rather than depicting the "day-to-day" or "year-to-year" weather fluctuation. Climate projections will vary according to different greenhouse gas concentration 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 AR5 are summarized below. Further details are available on the webpage www.climatechange2013.org.