The Global Warming Hiatus Simulated in HadGEM2-AO Based on RCP8.5

National Institute of Meteorological Research, Jeju 697-845, KoreaAbstract: Despite the greenhouse gases like carbon dioxide have steadily increased in atmosphere, the overall trend of theglobal average surface air temperature has stalled during the last decade (2002-present). This phenomenon is often calledhiatus or warming pause, which is challenging the prevailing view that anthropogenic forcing causes warmingenvironment. Our study characterized the hiatus by analyzing the HadGEM2-AO (95 yrs) simulation data based onRCP8.5 scenario. The PC2 time series from the EOF of the zonal mean vertical ocean temperature has been defined asthe index that represents the warming pause. The relationship between the hiatus, ENSO and the changes in climatesystem are identified by utilizing the newly defined PC2. Since the La Nina index (defined as the negative of NINO3index) leads PC2 by about 11 months, it may be possible that the La Nina causes the warming to be interrupted. We alsoshow that the cooling of the climate system closed tied to the heat penetration into the deep ocean, indicating theweakening the warming rate is due to the oceanic heat uptake. Finally, the global warming hiatus is characterized by theanomalous warming in Arctic region as well as the intensification of the trade wind in the equatorial Pacific.Keywords: warming hiatus, HadGEM2-AO, La Nina, oceanic heat uptake요약: 대기 중 이산화탄소 등의 농도가 지속적으로 증가하고 있음에도 최근 10여 년 동안(2002-현재) 전지구 지표 온도는 거의 답보상태에 머물러 있다. 이처럼 온실기체 강제력에도 불구하고, 지구 온난화 경향이 사라진 듯 보이는 현상을 지구 온난화 멈춤(hiatus)이라 한다. 이 연구는 HadGEM2-AO가 모의한 RCP8.5 시나리오 실험(95년간) 자료를 분석하여, 온난화 멈춤 시기의 특징을 분석하였다. 온난화 멈춤 기간을 나타내는 시계열은 동서 평균한 연직 해수 온도 분포를 EOF 분석하여 구한 두 번째 PC (PC2)로 정의하였다. PC2를 이용하여 온난화 멈춤과 엔소와의 관련성, 기후시스템의 변화 등을 분석하였다. 라니냐 지수(NINO3지수에