Figure 3

The relationship between risks from climate change, temperature change, cumulative CO ₂ emissions, and changes in annual GHG emissions by 2050. The pink plume is from WGI complex models and includes the uncertainty from non-CO₂ gases and climate and carbon cycle uncertainty, using the likely range. The ellipses show results from the WGIII models, using a simple climate model, not including climate and carbon cycle uncertainty. The red lines are an example of how to read the figure; they are not included in the version of the released Synthesis Report. Special thanks to Stéphane Hallegate and IPCC colleagues for guiding authors and parties through this application. The horizontal red line in the top part of the figure indicates a 1.5°C warming over pre-industrial times, connected to cumulative CO₂ emission levels, for the average climate response (solid vertical line down), for large climate sensitivity (dotted vertical line down to the left of the solid line), and for low climate sensitivity (dotted vertical line down to the right of the solid line). Through the horizontal lines in the bottom part of the graphic, levels of risks can now be connected to GHG emission changes by 2050, again for an average climate response and high- and low-sensitivity scenarios. Added uncertainty arises from action on non-CO₂ gases, timing of pre-2050 action, and ambition of post-2050 action [23,35].