Abstract
Climate forcing and feedbacks are diagnosed from seven slab‐ocean GCMs for 2 × CO 2 using a regression method. Results are compared to those using conventional methodologies to derive a semi‐direct forcing due to tropospheric adjustment, analogous to the semi‐direct effect of absorbing aerosols. All models show a cloud semi‐direct effect, indicating a rapid cloud response to CO 2 ; cloud typically decreases, enhancing the warming. Similarly there is evidence of semi‐direct effects from water‐vapour, lapse‐rate, ice and snow. Previous estimates of climate feedbacks are unlikely to have taken these semi‐direct effects into account and so misinterpret processes as feedbacks that depend only on the forcing, but not the global surface temperature. We show that the actual cloud feedback is smaller than what previous methods suggest and that a significant part of the cloud response and the large spread between previous model estimates of cloud feedback is due to the semi‐direct forcing.
Keywords
Forcing (mathematics)Cloud feedbackEnvironmental scienceCloud forcingClimatologyRadiative forcingClimate modelAtmospheric sciencesCloud computingClimate changeClimate sensitivityGeologyComputer scienceOceanography
Affiliated Institutions
Related Publications
Aerosol‐cloud semi‐direct effect and land‐sea temperature contrast in a GCM
Simulations with the CAM3 climate model show that prescribed heating by anthropogenic aerosols significantly affects cloud cover. Globally the dominant effect is a decrease in m...
Causes of Higher Climate Sensitivity in CMIP6 Models
Abstract Equilibrium climate sensitivity, the global surface temperature response to CO doubling, has been persistently uncertain. Recent consensus places it likely within 1.5–4...
A comparison of present and doubled CO<sub>2</sub> climates and feedbacks simulated by three general circulation models
The present and doubled CO 2 equilibrium climates simulated by slab ocean versions of the atmospheric general circulation models from the Commonwealth Scientific and Industrial ...
Bounding the role of black carbon in the climate system: A scientific assessment
Abstract Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical ...
Seasonal variation of cloud radiative forcing derived from the Earth Radiation Budget Experiment
The NASA Earth Radiation Budget Experiment (ERBE), flying aboard multiple satellites, is providing new insights into the climate system. Monthly averaged clear‐sky and cloudy sk...
Publication Info
- Year
- 2008
- Type
- article
- Volume
- 35
- Issue
- 4
- Citations
- 128
- Access
- Closed
External Links
Social Impact
Altmetric
PlumX Metrics
Social media, news, blog, policy document mentions
Citation Metrics
128
OpenAlex
Cite This
Timothy Andrews,
Piers Forster
(2008).
CO<sub>2</sub> forcing induces semi‐direct effects with consequences for climate feedback interpretations.
Geophysical Research Letters
, 35
(4)
.
https://doi.org/10.1029/2007gl032273
Identifiers
- DOI
- 10.1029/2007gl032273