The slowdown in global mean surface temperature rise - Grantham Note 1

Authors: Dr Simon Buckle and Dr Flora Whitmarsh

Overview

• Global mean surface temperature increased by about 0.85°C over the period 1880-2012. Each of the last three decades has been warmer than all previous decades in the instrumental record and the decade of the 2000s has been the warmest.
• Climate change is a long term trend, and a few decades worth of data are needed to separate the warming trend from natural variability.
• The recent slowdown in the observed temperature trend for 1998 - 2012 relative to 1951 - 2012 is probably attributable in roughly equal measure to cooling from internal climate variability and reduced external forcing of the climate system.
• Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. In the absence of major volcanic eruptions or long-term changes in solar energy reaching the Earth, global mean surface temperature for the period 2016 - 2035 is likely to be in the range of 0.3°C to 0.7°C higher than for 1986 -2005.
• Global mean surface temperatures are projected to continue to rise further over the 21st Century. With very strong mitigation action, global mean surface temperature by the end of the century, relative to the average over 1850 – 1900, is unlikely to exceed 2°C. However, if current emission trends continue, an increase of more than 4°C is as likely as not.

View all Grantham Notes