Cerfacs (CECI, CNRS/Cerfacs) researchers have analyzed the 21st century climate projections simulated by an ensemble of 27 coupled models from the Coupled Model Intercomparison Project phase 5 (CMIP5) under a buisness as usual greenhouse gas scenario. At the end of the century, the multimodel results indicate a tenfold increase of the number of warm records compared to the first half of the twentieth century (taken as a climate with no detectable human influence) and the quasi-disappearance of cold records. They have then estimated a time of emergence of the summer temperature record anthropogenic influence in a world under a business as usual greenhouse gas emission scenario: 2020 for the cold records and 2030 for the warm ones with an uncertainty of ± 20 years.
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Reference: Bador, M., L. Terray, J. Boé, 2016: Emergence of human influence on summer record-breaking temperatures Over Europe. Geophys. Res. Lett., 43, 404-412. DOI: 10.1002/2015GL066560.