The latest climate models and observations offer unprecedented opportunities to reduce the remaining uncertainties in future climate change, according to a new study. 

Although the human impact of recent climate change is now clear, future climate change depends on how much additional greenhouse gas is emitted by humanity and also how sensitive the Earth System is to those emissions.  

Reducing uncertainty in the sensitivity of the climate to carbon dioxide emissions is necessary to work-out how much needs to be done to reduce the risk of dangerous climate change, and to meet international climate targets. 

The study, which emerged from an intense workshop at the Aspen Global Change Institute in August 2017 (read more about the workshop at https://www.crescendoproject.eu/crescendo-scientists-organise-earth-system-model-evaluation-workshop-aspen-global-change-institute-30th-july-4th-august-2017/), explains how new evaluation tools will enable a more complete comparison of models to ground-based and satellite measurements. 

Produced by a team of 29 international authors, the study is published in Nature Climate Change.

Lead author Veronika Eyring, member of CRESCENDO at DLR in Germany, said: “We decided to convene a workshop at the AGCI to discuss how we can make the most of these new opportunities to take climate model evaluation to the next level”. 

The agenda laid-out includes plans to make the increasing number of global climate models which are being developed worldwide, more than the sum of the parts 

One promising approach involves using all the models together to find relationships between the climate variations being observed now and future climate change.  

“When considered together, the latest models and observations can significantly reduce uncertainties in key aspects of future climate change”, said workshop co-organiser Professor Peter Cox of the University of Exeter in the UK and CRESCENDO WP8 lead. 

The new paper is motivated by a need to rapidly increase the speed of progress in dealing with climate change. It is now clear that humanity needs to reduce emissions of carbon dioxide very rapidly to avoid crashing through the global warming limits of 1.5oC and 2oC set out in the Paris agreement.   

However, adapting to the climate changes that we will experience requires much more detailed information at the regional scale. “The pieces are now in place for us to make progress on that challenging scientific problem”, explained Veronika Eyring. 

Figure above reproduced from Eyring et al. (2018): Schematic diagram of the workflow for CMIP Evaluation Tools running alongside the ESGF. The tools will routinely produce a broad characterization of model performance for CMIP model output utilizing relevant observations and reanalyses and running alongside the ESGF infrastructure. MMM: multi-model mean; WGCM: Working Group on Coupled Modelling; WGNE: Working Group on Numerical Experimentation; ECVs: essential climate variables. 

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