scholarly journals Comments on “Rethinking the Lower Bound on Aerosol Radiative Forcing”

2018 ◽  
Vol 31 (22) ◽  
pp. 9407-9412 ◽  
Author(s):  
Ben B. B. Booth ◽  
Glen R. Harris ◽  
Andy Jones ◽  
Laura Wilcox ◽  
Matt Hawcroft ◽  
...  
Keyword(s):  
Lower Bound ◽  
Radiative Forcing ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

scholarly journals Reply to “Comments on ‘Rethinking the Lower Bound on Aerosol Radiative Forcing’”

2018 ◽  
Vol 31 (22) ◽  
pp. 9413-9416
Author(s):  
Bjorn Stevens
Keyword(s):  
Lower Bound ◽  
Little Ice Age ◽  
Radiative Forcing ◽  
Ice Age ◽  
Top Down ◽  
Aerosol Radiative Forcing ◽  
Poor Understanding ◽  
Aerosol Cloud Interactions ◽  
Lines Of Evidence ◽  
Aerosol Radiative

This reply addresses a comment questioning one of the lines of evidence I used in a 2015 study (S15) to argue for a less negative aerosol radiative forcing. The comment raises four points of criticism. Two of these have been raised and addressed elsewhere; here I additionally show that even if they have merit the S15 lower bound remains substantially (0.5 W m–2) less negative than that given in the AR5. Regarding the two other points of criticism, one appears to be based on a poor understanding of the nature of S15’s argument; the other rests on speculation as to the nature of the uncertainty in historical SO2 estimates. In the spirit of finding possible flaws with the top-down constraints from S15, I instead hypothesize that an interesting—albeit unlikely—way S15 could be wrong is by inappropriately discounting the contribution of biomass burning to radiative forcing through aerosol–cloud interactions. This hypothesis is interesting as it opens the door for a role for the anthropogenic (biomass) aerosol in causing the Little Ice Age and again raises the specter of greater warming from ongoing reductions in SO2 emissions.

Origins of a relatively tight lower bound on anthropogenic aerosol radiative forcing from Bayesian analysis of historical observations

2021 ◽  
pp. 1-51
Author(s):  
Anna Lea Albright ◽  
Cristian Proistosescu ◽  
Peter Huybers
Keyword(s):  
Lower Bound ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Credible Interval ◽  
Ocean Heat Uptake ◽  
Aerosol Radiative Forcing ◽  
Joint Inference ◽  
Aerosol Forcing ◽  
Wide Range ◽  
Aerosol Radiative

AbstractA variety of empirical estimates have been published for the lower bounds on aerosol radiative forcing, clustered around -1.0 Wm−2 or -2.0 Wm−2. The reasons for obtaining such different constraints are not well understood. In this study, we explore bounds on aerosol radiative forcing using a Bayesian model of aerosol forcing and Earth’s multi-timescale temperature response to radiative forcing. We first demonstrate the ability of a simple aerosol model to emulate aerosol radiative forcing simulated by ten general circulation models. A joint inference of climate sensitivity and effective aerosol forcing from historical surface temperatures is then made over 1850–2019. We obtain a maximum likelihood estimate of aerosol radiative forcing of -0.85 Wm−2 [5-95% credible interval -1.3 to -0.50 Wm−2] for 2010–2019 relative to 1750 and an equilibrium climate sensitivity of 3.4°C [5-95% credible interval 1.8 to 6.1°C]. The wide range of climate sensitivity reflects difficulty in empirically constraining long-term responses using historical temperatures, as noted elsewhere. A relatively tight bound on aerosol forcing is nonetheless obtained from the structure of temperature and aerosol precursor emissions and, particularly, from the rapid growth in emissions between 1950–1980. Obtaining a fifth-percentile lower bound on aerosol forcing around -2.0 Wm−2 requires prescribing internal climate variance that is a factor of five larger than the CMIP6 mean and assuming large, correlated errors in global temperature observations. Ocean heat uptake observations may further constrain aerosol radiative forcing but require a better understanding of the relationship between time-variable radiative feedbacks and radiative forcing.

scholarly journals Rethinking the Lower Bound on Aerosol Radiative Forcing

2015 ◽  
Vol 28 (12) ◽  
pp. 4794-4819 ◽  
Author(s):  
Bjorn Stevens
Keyword(s):  
Lower Bound ◽  
Radiative Forcing ◽  
Time History ◽  
Historical Record ◽  
Natural State ◽  
Model Parameters ◽  
Aerosol Radiative Forcing ◽  
Aerosol Forcing ◽  
The Individual ◽  
Aerosol Radiative

Abstract Based on research showing that in the case of a strong aerosol forcing, this forcing establishes itself early in the historical record, a simple model is constructed to explore the implications of a strongly negative aerosol forcing on the early (pre-1950) part of the instrumental record. This model, which contains terms representing both aerosol–radiation and aerosol–cloud interactions, well represents the known time history of aerosol radiative forcing as well as the effect of the natural state on the strength of aerosol forcing. Model parameters, randomly drawn to represent uncertainty in understanding, demonstrate that a forcing more negative than −1.0 W m−2 is implausible, as it implies that none of the approximately 0.3-K temperature rise between 1850 and 1950 can be attributed to Northern Hemisphere forcing. The individual terms of the model are interpreted in light of comprehensive modeling, constraints from observations, and physical understanding to provide further support for the less negative (−1.0 W m−2) lower bound. These findings suggest that aerosol radiative forcing is less negative and more certain than is commonly believed.

scholarly journals The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

2019 ◽  
Vol 46 (7) ◽  
pp. 4039-4048 ◽  
Author(s):  
S. T. Turnock ◽  
G. W. Mann ◽  
M. T. Woodhouse ◽  
M. Dalvi ◽  
F. M. O'Connor ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Cloud Water ◽  
Aerosol Radiative Forcing ◽  
Water Ph ◽  
The Impact ◽  
Aerosol Radiative

scholarly journals Aerosol radiative forcing over a tropical urban site in India

2004 ◽  
Vol 31 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. Pandithurai ◽  
R. T. Pinker ◽  
T. Takamura ◽  
P. C. S. Devara
Keyword(s):  
Radiative Forcing ◽  
Urban Site ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

Aerosol radiative forcing due to enhanced black carbon at an urban site in India

2002 ◽  
Vol 29 (18) ◽  
pp. 27-1-27-4 ◽  
Author(s):  
S. Suresh Babu ◽  
S. K. Satheesh ◽  
K. Krishna Moorthy
Keyword(s):  
Black Carbon ◽  
Radiative Forcing ◽  
Urban Site ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

scholarly journals Aerosol radiative forcing during clear, hazy, and foggy conditions over a continental polluted location in north India

2006 ◽  
Vol 111 (D20) ◽  
Author(s):  
S. Ramachandran ◽  
R. Rengarajan ◽  
A. Jayaraman ◽  
M. M. Sarin ◽  
Sanat K. Das
Keyword(s):  
Radiative Forcing ◽  
North India ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative

The influence of a south Asian dust storm on aerosol radiative forcing at a high-altitude station in central Himalayas

2011 ◽  
Vol 32 (22) ◽  
pp. 7827-7845 ◽  
Author(s):  
Atul K. Srivastava ◽  
P. Pant ◽  
P. Hegde ◽  
Sachchidanand Singh ◽  
U. C. Dumka ◽  
...  
Keyword(s):  
High Altitude ◽  
South Asian ◽  
Dust Storm ◽  
Radiative Forcing ◽  
Asian Dust ◽  
Central Himalayas ◽  
Aerosol Radiative Forcing ◽  
Asian Dust Storm ◽  
Aerosol Radiative

Potential of lidar backscatter data to estimate solar aerosol radiative forcing

2006 ◽  
Vol 45 (4) ◽  
pp. 770 ◽  
Author(s):  
Manfred Wendisch ◽  
Detlef Müller ◽  
Ina Mattis ◽  
Albert Ansmann
Keyword(s):  
Radiative Forcing ◽  
Aerosol Radiative Forcing ◽  
Aerosol Radiative
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