Translating global mean temperature changes into regional changes


Effectively communicating the urgency of reducing carbon dioxide (CO2 ) emissions may require the design of climate targets that are more directly aligned with individual and regional interest.

The urgency of reducing carbon dioxide (CO2) emissions is difficult to communicate to the general public and policy makers when only global temperature targets, such as the widely discussed increase in two degrees Celsius above the pre-industrial level, are considered. However translating changes in global temperature (and the associated CO2 emissions) into regional- and impact-related climate changes may be more powerful because such targets are more directly aligned with individual national interests. Such an approach is presented in a new study published by C2SM-members Sonia Seneviratne and Reto Knutti (among others) in Nature. Using the wealth of data made available by the climate model inter comparison initiative (so-called CMIP5) in the framework of the 5th IPCC Assessment Report, the authors showed that regional indices such as regional changes in extreme temperatures and precipitation scale robustly with global temperature across scenarios, and thus with cumulative CO2 emissions. Providing climate and climate impact information at a regional scale could help in the development of solutions - in particular when political decision are needed in the context of climate negotiations and adaptation - and when communicating with the public.

Figure 3 (from Seneviratne et al., 2016): Scaling between regional changes in annual temperature extremes and changes in global mean temperature, with associated global cumulative CO2 emissions targets for annual maximum daytime temperature (TXx) in the Mediterranean region (a) the contiguous USA (b), and central Brazil (c), and for the annual minimum night-time temperature (TNn) in the Arctic (d), for land grid cells only.  Solid black line: ensemble average until 2010 (combined with RCP8.5 for 2006–2010); solid red (blue) line: ensemble average of future projections for RCP8.5 (RCP4.5) from 25 (22) simulations; red shaded area: total range for all simulations; dashed black line: identity (1:1) line; grey dashed lines: temperature or CO2 emissions associated with 2 °C increase in global mean and regional extreme temperatures, respectively. 
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Fri Jun 23 20:47:40 CEST 2017
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