To ask Her Majesty’s Government, further to the Written Answer by Lord Prior of Brampton on 1 February (HL4937), what evidence they have for their statement that the observed evidence of global average surface temperature is not consistent with natural internal variability.
14 March 2017
Evidence that observed global average surface temperatures are not consistent with natural internal variability in the climate system can be found in Working Group I of the IPCC’s 5th Assessment Report (AR5 WGI).
Observations show that global average surface temperature has risen by between 0.6 to 0.7°C since 1951. AR5 WGI concluded that it was virtually certain (>99% probability) that natural internal variability alone could not account for this observed increase in temperature. Amongst other reasons, it showed that the spatial pattern of observed warming differed from that associated with internal variability. AR5 WGI stated that more than half of the observed increase in global average surface temperature from 1951 to 2010 was extremely likely (> 95% probability) due to the anthropogenic increase in atmospheric greenhouse gas concentrations and other anthropogenic forcings together.