In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 2 ( 2021-01-27), p. 1105-1126
Abstract:
Abstract. Feedbacks play a fundamental role in determining the magnitude of the
response of the climate system to external forcing, such as from
anthropogenic emissions. The latest generation of Earth system models
includes aerosol and chemistry components that interact with each other and
with the biosphere. These interactions introduce a complex web of feedbacks
that is important to understand and quantify. This paper addresses multiple pathways for aerosol and chemical feedbacks in
Earth system models. These focus on changes in natural emissions (dust, sea
salt, dimethyl sulfide, biogenic volatile organic compounds (BVOCs) and
lightning) and changes in reaction rates for methane and ozone chemistry.
The feedback terms are then given by the sensitivity of a pathway to climate
change multiplied by the radiative effect of the change. We find that the overall climate feedback through chemistry and aerosols is
negative in the sixth Coupled Model Intercomparison Project (CMIP6) Earth
system models due to increased negative forcing from aerosols in a climate
with warmer surface temperatures following a quadrupling of CO2
concentrations. This is principally due to increased emissions of sea salt
and BVOCs which are sensitive to climate change and cause strong
negative radiative forcings. Increased chemical loss of ozone and methane
also contributes to a negative feedback. However, overall methane lifetime is
expected to increase in a warmer climate due to increased BVOCs. Increased
emissions of methane from wetlands would also offset some of the negative
feedbacks. The CMIP6 experimental design did not allow the methane lifetime
or methane emission changes to affect climate, so we found a robust negative
contribution from interactive aerosols and chemistry to climate sensitivity
in CMIP6 Earth system models.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-1105-2021
DOI:
10.5194/acp-21-1105-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1