scholarly journals Bounding global aerosol radiative forcing of climate change

2020 ◽  
Author(s):  
Nicolas Bellouin ◽  
Keyword(s):  
Radiative Forcing ◽  
Review Paper ◽  
Aerosol Radiative Forcing ◽  
The Past ◽  
Open Questions ◽  
Substantial Progress ◽  
Theoretical Considerations ◽  
Present Understanding ◽  
Lines Of Evidence ◽  
Aerosol Radiative

<p>Aerosol radiative forcing plays an important role in the attribution of past climate changes, estimates of future allowable carbon emissions, and the assessment of potential geoengineering solutions. Substantial progress made over the past 40 years in observing, understanding, and modelling aerosol processes helped quantify aerosol radiative forcing, but uncertainties remain large.</p><p>In spring 2018, under the auspices of the World Climate Research Programme's Grand Science Challenge on Clouds, Circulation and Climate Sensitivity, thirty-six experts gathered to take a fresh and comprehensive look at present understanding of aerosol radiative forcing and identify prospects for progress on some of the most pressing open questions. The outcome of that meeting is a review paper, Bellouin et al. (2019), accepted for publication in Reviews of Geophysics. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. A substantial achievement is to focus on lines of evidence rather than a survey of past results or expert judgement, and to make the open questions much more specific.</p><p>This talk will present the key messages and arguments of the review and identify work that show promise for improving the quantification of aerosol radiative forcing.</p>

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.

scholarly journals An empirical model of global climate – Part 2: Implications for future temperature

2012 ◽  
Vol 12 (9) ◽  
pp. 23913-23974 ◽  
Author(s):  
N. R. Mascioli ◽  
T. Canty ◽  
R. J. Salawitch
Keyword(s):  
Surface Temperature ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Global Climate ◽  
Climate Feedback ◽  
Anthropogenic Aerosol ◽  
Aerosol Radiative Forcing ◽  
The Past ◽  
Global Surface ◽  
Aerosol Radiative

Abstract. IPCC (2007) has shown that atmosphere-ocean general circulation models (GCMs) from various research centers simulate the rise in global mean surface temperature over the past century rather well, yet provide divergent estimates of temperature for the upcoming decades. We use an empirical model of global climate based on a multiple linear regression (MLR) analysis of the past global surface temperature anomalies (ΔT) to explore why GCMs might provide divergent estimates of future temperature. Our focus is on the interplay of three factors: net anthropogenic aerosol radiative forcing (NAA RF), climate feedback (water vapor, clouds, surface albedo) in response to greenhouse gas radiative forcing (GHG RF), and ocean heat export (OHE). Our model is predicated on two key assumptions: whatever climate feedback is needed to account for past temperature rise will persist into the future and whatever fraction of anthropogenic RF (GHG RF + NAA RF) is exported to the oceans to match the observed rise in ocean heat content will also persist. Even with these assumptions, modeled future ΔT mimics the behavior of GCMs because the ~110 record of global surface temperature can not distinguish between two possibilities. If anthropogenic aerosols presently exert small cooling on global climate, feedback must be weak and the future rise in global average surface temperature in 2053, the time CO2 is projected to double according to RCP 8.5, could be moderate. If aerosols presently exert large cooling of global climate, feedback must be large and future ΔT when CO2 doubles could be substantial. Reduced uncertainty for climate projection requires observationally based constraints that can narrow the uncertainties that presently exist for net anthropogenic aerosol radiative forcing as well as the totality of feedbacks that occur in response to a GHG RF perturbation. GCMs are often compared by evaluating the equilibrium response to a doubling of CO2, termed climate sensitivity. In our model framework, ΔT at the time CO2 doubles is nearly independent of OHE, because climate feedback must be adjusted to properly simulate observed temperature. Our simulations show that if a small fraction of anthropogenic RF is exported to the ocean, equilibrium climate sensitivity closely represents the modeled ΔT at the time CO2 doubles. Conversely, if this fraction is large, ΔT when CO2 doubles is much less than the equilibrium climate sensitivity (i.e. the model is now far from equilibrium). Similar behavior likely occurs within GCMs. We therefore suggest the dependence of climate sensitivity on OHE be factored into analyses that use this metric to compare and evaluate GCMs.

scholarly journals Recent progress understanding pathophysiology and genesis of brain AVM—a narrative review

2021 ◽  
Author(s):  
Hans-Jakob Steiger
Keyword(s):  
Large Degree ◽  
Advanced Imaging ◽  
Genetic Origin ◽  
The Past ◽  
Open Questions ◽  
Brain Avm ◽  
Pubmed Search ◽  
Substantial Progress ◽  
The Individual ◽  
Arterial Aneurysms

AbstractConsiderable progress has been made over the past years to better understand the genetic nature and pathophysiology of brain AVM. For the actual review, a PubMed search was carried out regarding the embryology, inflammation, advanced imaging, and fluid dynamical modeling of brain AVM. Whole-genome sequencing clarified the genetic origin of sporadic and familial AVM to a large degree, although some open questions remain. Advanced MRI and DSA techniques allow for better segmentation of feeding arteries, nidus, and draining veins, as well as the deduction of hemodynamic parameters such as flow and pressure in the individual AVM compartments. Nonetheless, complete modeling of the intranidal flow structure by computed fluid dynamics (CFD) is not possible so far. Substantial progress has been made towards understanding the embryology of brain AVM. In contrast to arterial aneurysms, complete modeling of the intranidal flow and a thorough understanding of the mechanical properties of the AVM nidus are still lacking at the present time.

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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