Sentences with phrase «aerosol forcings»
The phrase "aerosol forcings" refers to the influence or impact that aerosols, which are tiny particles suspended in the air, have on the Earth's climate. Aerosols can either warm or cool the planet by interacting with sunlight and affecting cloud formation. This term describes the effect aerosols have on the amount of heat retained or reflected by the atmosphere, which can contribute to climate change. Full definition
By the way, what is the basis for claiming that the negative aerosol forcing estimate has been reduced?
skepticalscience.com
The bottom three curves show the history of indirect aerosol forcing used in the top three curves.
However, this doesn't translate to a satellite - based estimate of total aerosol forcing because many of these studies only cover indirect effects.
This is because, following current best estimates, negative aerosol forcing has substantially offset the GHG - induced warming.
It therefore is their estimate for the total all - history anthropogenic direct aerosol forcing.
I predict the calculated aerosol forcing from these models is about to undergo a significant drop.
That report relies on studies that include the large aerosol forcing uncertainty, so criticizing my paper for that would be inconsistent.
Climate model sensitivity to a doubling of atmospheric CO2 is intrinsic to the model itself and has nothing to do with what aerosol forcings are.
The uncertainties in aerosol forcing also have some consequences for deciding which models have the «best» climate sensitivity, though the precise implications of that are a bit harder to see.
The model that is most consistent with the observed evolution has the smallest aerosol forcing.
Why, then, is − 1.8 W / m2 for indirect aerosol forcing highly unlikely?
On the subject of the bigger picture — their key point that uncertainty in aerosol forcing needs to be better constrained is something that is very relevant.
Is there no «average natural aerosol forcing» that is assumed in the projections?
The effect on radiative forcing of assuming different values for indirect aerosol forcing.
However, it is clear that ocean variability interferes with aerosol forcing as well as with any other forcing.
The inverse estimates summarised in Table 9.1 suggest that to be consistent with observed warming, the net aerosol forcing over the 20th century should be negative with likely ranges between — 1.7 and — 0.1 W m — 2.
Now, so far as I know, model aerosol forcing values are generally for the change from the 1850s, or thereabouts, to ~ 2000, not — as is the AR5 estimate — for the change from 1750.
Lamarque, D. Olivié, T. Richardson, D. Shindell, and T. Takemura, 2018: A PDRMIP multi-model study on the impacts of regional aerosol forcings on global and regional precipitation.
But questions remained concerning the degree of decadal variability, the length of the record and the balance in the models between aerosol forcing and climate sensitivity (which can't really be disentangled using this measure).
Gregory 02 provides a good explanation for the basis of what I have done, although its observational data (and its model derived aerosol forcing change) has now been superceded.
In the light of the analyses of the characteristics of the models used in Shindell's analysis, as outlined above, combined with the evidence that Shindell's aerosol forcing bias - adjustment is very likely understated and that his results» sensitivity to it makes his TCR estimate far more uncertain than claimed, it is difficult to see that any weight should be put on Shindell's findings.
There is also a fairly large increase in modelled sulfate load over the Tropical North Atlantic from about 1960, which is presumably the main cause of modelled present day strong aerosol forcing off the West African coast, as depicted in Booth et al. figure 4b.
The most important issue for high / low ECS (GHG vs. Aerosol forcing impacts on GMST) is the elephant in the room, not included in BC17.
Likely no net aerosol forcing effect.