Attribution of the record warm 2014 in Central England and the time of emergence of a warming signal

Abstract:

The exceptional length of the Central England Temperature (CET) series makes it a useful tool in climate variability studies. Here we use it for an event attribution of the 2014 record temperatures and to calculate the time of emergence of an anthropogenic signal.

Last year, Central England experienced its warmest year in a record extending back to 1659. Using both state-of-the-art climate models and empirical techniques, our analysis shows a substantial and significant increase in the likelihood of record-breaking warm years, such as 2014, due to human influences on the climate. It is very likely that anthropogenic forcings on the climate have increased the chances of record warm years in Central England by at least 13-fold. This study points to a large influence of human activities on extreme warm years despite the small region of study and the variable climate of Central England. Our analysis shows that climate change is clearly visible on the local-scale.

The time of emergence of an anthropogenic signal in the CET series was also calculated. Earlier emergence was found in mean temperatures than extreme indices and also at longer temporal scales, such as annual values when compared with individual months or dates. This is due to reduced interannual variability on these timescales. Emergence of an anthropogenic signal could be detected in daily and monthly CET values in late summer and early autumn.