Slowdown of global surface air temperature increase and acceleration of ice melting. Issue 7 (27th July 2017)

• Record Type: Journal Article
• Authors: Berger, André; Yin, Qiuzhen; Nifenecker, Hervé; Poitou, Jean
• Is Part Of: Earth's future. Volume 5:Issue 7(2017)
• Page Start: 811
• Page End: 822
• Publication Date: 2017-07-27
• Subjects: global warming slowdown -- ice melting acceleration -- Earth energy budegt; Environmental sciences -- Periodicals; Environmental sciences; Periodicals; 550
• DOI: 10.1002/2017EF000554
• Languages: English
• ISSNs: 2328-4277

Abstract

Abstract: Although recent decades have been the warmest since 1850, and global mean temperatures during 2015 and 2016 beat all instrumental records, the rate of increase in global surface air temperature (GSAT) significantly decreased at the beginning of the 21st Century. In this context, we examine the roles of ice melting and associated increase in sea‐water mass, both of which significantly increased at the same time as GSAT decreased. Specifically, we show that (1) the slowdown of the rate of increase in GSAT between the specific periods 1992–2001 and 2002–2011 exists in all three climate records analyzed and is statistically significant at the 5% level amounting between 0.029 and 0. 036°C/yr and leaving an energy of 14.8–18.4 10 19 J/yr available; (2) the increase of the atmosphere‐related ice melt between these two periods amounts to 316 Gt/yr which requires 10.5 10 19 J/yr, that is, between 57% and 71% of the energy left by the slowdown; and (3) the energy budget shows, therefore, that the heat required to melt this additional 316 Gt/yr of ice is of the same order as the energy needed to warm the atmosphere during the decade 2002–2011 as much as during the previous one, suggesting a redistribution of heat within the atmosphere–cryosphere system. Key Points: Our analysis of climate and ice records show a slowdown of the rate of increase in global surface air temperature and an acceleration of ice melting from 1992–2001 to 2002–2011, both statistically significant at the 5% level The energies involved in both processes are of the same order of magnitude, indicating a redistribution of heat within the atmosphere–cryosphere system Plain Language Summary: Although the last decade is the warmest decade in the instrumental record and CO2 continues to rise, global surface air temperature has not increased as much as before over the last 10–15 years, leading to the so‐called hiatus or slowdown of the global warming. This is a key event which has still not received any definitive explanation, although many possible causes have already been adduced. Here we take into account the almost simultaneous phenomena which arose at the beginning of the 21st century: acceleration in the disappearance of the summer arctic sea ice, increase of the rate of ice sheets and glacier melting and of seal‐level rise, and the appearance of a decrease of the warming trend of the atmosphere. Our calculations based on three climate records show that the energy left in the atmosphere by the slowdown of the global warming is pretty similar to the energy requested to melt the ice over the same period. While the heat content of the atmosphere alone shows a leveling off after 2002, no such behavior is observed when the heat of ice melting is added, suggesting a redistribution of heat within the atmosphere–cryosphere system.