When looking at projections and impact assessments for the emissions pathways described by the Representative Concentration Pathways (RCPs), it is possible to use a rough rule of thumb to convert to warming levels, e.g. RCP8.5 is roughly equivalent to +2 °C warming level in the late 2030s and the 2040s or +3 °C in around 2050 to 2080. This is less precise than using more formal methods, but it is useful to assess and interpret existing results from RCPs into a warming level lens.
Reaching Global Warming Levels page for more
To produce projections, it is important to use methods of estimating climate change at warming levels that are reliable and consistent with international good practice. There are various methods to estimate climate change at different global warming levels, see James et al. (2017) for a summary of many of them.
Download Technical Note 3 - Global Warming Levels methods
There are two methods used here – there are other approaches not used here but that could be used and compared in future (see Technical note 3).
This graph shows the global mean surface temperature simulated by Australia’s ACCESSS-1.0 model in 2005–2100 relative to the 1850–1900 baseline, and the years detected for each warming level, see Technical note 3 for more details.