A modeling study of effective radiative forcing and climate response due to increased methane concentration

摘要

An atmospheric general circulation model BCC_AGCM2.0 and observation data from ARIS were used to calculate the effective radiative forcing (ERF) due to increased methane concentration since pre-industrial times and its impacts on climate. The ERF of methane from 1750 to 2011 was 0.46 W m?2 by taking it as a well-mixed greenhouse gas, and the inhomogeneity of methane increased its ERF by about 0.02 W m?2. The change of methane concentration since pre-industrial led to an increase of 0.31 ?C in global mean surface air temperature and 0.02 mm d?1 in global mean precipitation. The warming was prominent over the middle and high latitudes of the Northern Hemisphere (with a maximum increase exceeding 1.4 ?C). The precipitation notably increased (maximum increase of 1.8 mm d?1) over the ocean between 10?N and 20?N and significantly decreased (maximum decrease >e0.6 mm d?1) between 10?S and 10?N. These changes caused a northward movement of pre-cipitation cell in the Intertropical Convergence Zone (ITCZ). Cloud cover significantly increased (by approximately 4%) in the high latitudes in both hemispheres, and sharply decreased (by approximately 3%) in tropical areas.