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Rapid Adjustments Cause Weak Surface Temperature Response to Increased Black Carbon Concentrations
Author(s) -
Stjern Camilla Weum,
Samset Bjørn Hallvard,
Myhre Gunnar,
Forster Piers M.,
Hodnebrog Øivind,
Andrews Timothy,
Boucher Olivier,
Faluvegi Gregory,
Iversen Trond,
Kasoar Matthew,
Kharin Viatcheslav,
Kirkevåg Alf,
Lamarque JeanFrançois,
Olivié Dirk,
Richardson Thomas,
Shawki Dilshad,
Shindell Drew,
Smith Christopher J.,
Takemura Toshihiko,
Voulgarakis Apostolos
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd027326
Subject(s) - radiative forcing , atmospheric sciences , environmental science , climatology , cloud cover , forcing (mathematics) , climate change , global warming , greenhouse gas , cloud forcing , mean radiant temperature , precipitation , climate model , global temperature , meteorology , geography , cloud computing , physics , geology , oceanography , computer science , operating system
We investigate the climate response to increased concentrations of black carbon (BC), as part of the Precipitation Driver Response Model Intercomparison Project (PDRMIP). A tenfold increase in BC is simulated by nine global coupled‐climate models, producing a model median effective radiative forcing of 0.82 (ranging from 0.41 to 2.91) W m −2 , and a warming of 0.67 (0.16 to 1.66) K globally and 1.24 (0.26 to 4.31) K in the Arctic. A strong positive instantaneous radiative forcing (median of 2.10 W m −2 based on five of the models) is countered by negative rapid adjustments (−0.64 W m −2 for the same five models), which dampen the total surface temperature signal. Unlike other drivers of climate change, the response of temperature and cloud profiles to the BC forcing is dominated by rapid adjustments. Low‐level cloud amounts increase for all models, while higher‐level clouds are diminished. The rapid temperature response is particularly strong above 400 hPa, where increased atmospheric stabilization and reduced cloud cover contrast the response pattern of the other drivers. In conclusion, we find that this substantial increase in BC concentrations does have considerable impacts on important aspects of the climate system. However, some of these effects tend to offset one another, leaving a relatively small median global warming of 0.47 K per W m −2 —about 20% lower than the response to a doubling of CO 2 . Translating the tenfold increase in BC to the present‐day impact of anthropogenic BC (given the emissions used in this work) would leave a warming of merely 0.07 K.