[A-CG46] エミュレータの開発と応用

[ACG46-P05] Anthropogenic contributions to slow warming over 1998-2012

*蘇 宣銘^1,3、塩竈 秀夫¹、田中 克正^1,2、立入 郁³、羽島 知洋³、渡辺 路生³、河宮 未知生³、高橋 潔¹、横畠 徳太¹ (1.国立研究開発法人国立環境研究所、2.Laboratoire des Sciences du Climat et de l’Environnement (LSCE), IPSL, CEA/CNRS/UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France、3.国立研究開発法人海洋研究開発機構)

キーワード：Slow warming、Temperature attribution、Methane and ODS、ENSO、Solar irradiance、SCM4OPT

The observed global mean surface temperature increases from 1998 to 2012 was slower than that since 1951. The relative contributions of all relevant factors including climate forcers, however, have not been comprehensively analyzed. Using a reduced-complexity climate model and an observationally constrained statistical model, we find that La Niña cooling and a descending solar cycle contributed approximately 50% and 26% of the total warming slowdown during 1998-2012 compared to 1951-2012. Furthermore, reduced ozone-depleting substances and methane accounted for roughly a quarter of the total warming slowdown, which can be explained by changes in atmospheric concentrations. We identify that human factors played an important role in slowing global warming during 1998-2012, shedding light on the evidence for controlling global warming by reducing greenhouse gas emissions.