Publication Date:
2017-10-17
Description:
Atmospheric black carbon (BC) absorbs solar radiation, and exacerbates global warming
through exerting positive radiative forcing (RF). However, the contribution of BC to
ongoing changes in global climate is under debate. Anthropogenic BC emissions, and
5 the resulting distribution of BC concentration, are highly uncertain. In particular, long
range transport and processes affecting BC atmospheric lifetime are poorly understood.
Here we discuss whether recent assessments may have overestimated present
day BC radiative forcing in remote regions. We compare vertical profiles of BC concentration
from four recent aircraft measurement campaigns to simulations by 13 aerosol
10 models participating in the AeroCom Phase II intercomparision. An atmospheric lifetime
of BC of less than 5 days is shown to be essential for reproducing observations
in remote ocean regions, in line with other recent studies. Adjusting model results to
measurements in remote regions, and at high altitudes, leads to a 25% reduction in
AeroCom Phase II median direct BC forcing, from fossil fuel and biofuel burning, over
15 the industrial era. The sensitivity of modeled forcing to BC vertical profile and lifetime
highlights an urgent need for further flight campaigns, close to sources and in remote
regions, to provide improved quantification of BC effects for use in climate policy.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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