Sentences with phrase «total aerosol forcing»

Put in a two - hemisphere energy - balance model and using observed hemispheric temperature changes and ocean heat uptake changes you can easily arrive at an independent total aerosol forcing estimate - one that also implies small net total aerosol forcings that are reasonably consistent with the latest observatiional findings.

Using the current version, HadCRUT4, of the surface temperature dataset used in a predecessor study, it obtains central estimates for total aerosol forcing and climate sensitivity of respectively -0.5 W / m ^ 2 and 1.6 ºC.

Of these, the smallest best estimate I can find is -0.85 W / m ^ 2, which means the reported -0.7 is unlikely to be representative of total aerosol forcing, whatever else it relates to.

When extra forcing of -0.25 or -0.5 W / m ^ 2 is added his prior mean total aerosol forcing is very substantially more negative than -0.7 W / m ^ 2 (the posterior mean without the extra indirect forcing).

Paul S «I'm fully aware what it says in the text» In that case, why did you deny that the SOD text gave a best estimate of -0.73 W / m ^ 2 for total aerosol forcing based on satellite observations?

The Skeie et al total aerosol forcing estimate is -0.8 W / m ^ 2, between the SOD main composite central estimate of -0.9 W / m ^ 2 and its satellite - observation only central estimate of -0.73 W / m ^ 2.

I guess that this is based on the assumption that the range of total aerosol forcing is correct in the IPCC assessment: -1.2 w / m2 -LSB--2.7 to -0.4] http://www.skepticalscience.com/despite-uncertainty-CO2-drives-the-climate.html That central value is almost on par with the CO2 forcing (+1.6), thus canceling most of it.

Effective ocean diffusivity, Kv, and total aerosol forcing, Faer, are estimated simultaneously with S.

For total aerosol forcing using the AR4 uncertainty ranges for individual components, the 90 % confidence range, by quadrature, is ± 0.86 W / m2 (see Table 4).

In particular, equilibrium climate sensitivity (S), effective vertical deep ocean diffusivity (Kv) and total aerosol forcing (Faer) have been estimated in this way.

This is not the subject but it seems that, in AR5 (sorry it is the leaked version), the mean total aerosol forcing is less (30 %) than this same forcing in AR4.

Nevertheless, the similarity between results from inverse and forward estimates of aerosol forcing strengthens confidence in estimates of total aerosol forcing, despite remaining uncertainties.

c 5 to 95 % inverse estimate of the total aerosol forcing in the year given relative to pre-industrial forcing.

These results typically provide a somewhat smaller upper limit for the total aerosol forcing than the estimates given in Chapter 2, which are derived from forward calculations and range between — 2.2 and — 0.5 W m — 2 (5 to 95 % range, median — 1.3 W m — 2).

Of these, the smallest best estimate I can find is -0.85 W / m ^ 2, which means the reported -0.7 is unlikely to be representative of total aerosol forcing, whatever else it relates to.

-LRB--0.9 W / m2 against -1.3 W / m2) On this link, http://data.giss.nasa.gov/modelforce/RadF.txt, NASA - GISS provides a total aerosol forcing, in 2011, of -1.84 W / m2.

When extra forcing of -0.25 or -0.5 W / m ^ 2 is added his prior mean total aerosol forcing is very substantially more negative than -0.7 W / m ^ 2 (the posterior mean without the extra indirect forcing).

Not exact matches

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

We don't know the total forcing that well, primarily because we don't know the aerosol (direct or indirect) effects.

Clearly, there are many positive forcings (warming influences) and negative forcings (cooling influences)-- the total includes methane, N2O, black carbon, small changes in sunlight, aerosols, etc..

The total of -0.7 W / m ^ 2 is the same as the best observational (satellite) total aerosol adjusted forcing estimate given in the leaked Second Order Draft of AR5 WG1, which includes cloud lifetime (2nd indirect) and other effects.

As noted above, two independent analyses [64], [72] yield a total (direct plus indirect) aerosol forcing in the past decade of about − 1.5 W / m2, half the magnitude of the GHG forcing and opposite in sign.

The 5 to 95 % estimates for the range of aerosol forcing relate to total or net fossil - fuel related aerosol forcing (in W m — 2).

In addressing the question of the effects of greenhouse gases on Atlantic tropical storms, it might clarify (and even partially defuse) the controversy to lump internal variability together with other forced responses (particularly aerosols), rather than to focus on internal variability vs the total forced response.

Surely the relative amounts of aerosols and greenhouse gas emissions is of the utmost importance when evaluating the total forcing.

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

In these experiments the climate sensitivity was 2.7 deg C for a doubling of CO2, the net aerosol forcing from 1940 to 2000 was around -0.7 W / m2 (55 % of the total forcing, -1.27, from 1850 to 2000), and the ocean uptake of heat was well - matched to recent observations.

The total warming from methane, nitrous oxide and aerosol emissions were each estimated from climate model simulations driven by historical forcing pathways for each gas, and were allocated to individual countries as described in section 2.

On your page, you show the results for HADCM3 aerosol and ozone (actually the difference between total forcing and GHG forcing, but should be approximately the same).

Given the total irrelevance of volcanic aerosols during the period in question, the only very modest effect of fossil fuel emissions and the many inconsistencies governing the data pertaining to solar irradiance, it seems clear that climate science has no meaningful explanation for the considerable warming trend we see in the earlier part of the 20th century — and if that's the case, then there is no reason to assume that the warming we see in the latter part of that century could not also be due to either some as yet unknown natural force, or perhaps simply random drift.

The one slightly fortuitous aspect to this is that the forcing from CO2 alone is around 1.5 W / m2, while if you add up all of the forcings, including warming factors (like CO2 and CH4) and cooling factors (like aerosols), you end up with a total around 1.6 W / m2 — i.e. all of the extra stuff we've put in over the years pretty much cancels out in the global mean.

«The overall slight rise (relative heating) of global total net flux at TOA between the 1980's and 1990's is confirmed in the tropics by the ERBS measurements and exceeds the estimated climate forcing changes (greenhouse gases and aerosols) for this period.

Given our very short and spotty data on the relative abundance (or importance) of the majority of these aerosols, and given our very poor understanding of the direct, indirect, and side effects of the majority of these aerosols, any numbers that anyone generates about their abundance, importance, or total radiative forcing are going to be a SWAG.

The top three curves show total anthropogenic forcing assuming central values for all components other than indirect aerosol forcing.

I can understand taking aerosol offsets from GHG forcing to get total forcing for example.

The total energy imbalance is expressed as net forcing, the sum of all the various forcings (eg - solar, aerosols, greenhouse gases, etc).

I was interested in the quantitative order of the mean overestimation of the total effective aerosol forcing (ERFaero) of the CMIP5 models.

It shows that (a) each model uses a different value for «Total anthropogenic forcing» that is in the range 0.80 W / m ^ -2 to 2.02 W / m ^ -2 but (b) each model is forced to agree with the rate of past warming by using a different value for «Aerosol forcing» that is in the range -1.42 W / m ^ -2 to -0.60 W / m ^ -2.

IPCC tells us that 93 % of the past forcing was from anthropogenic components and that all other anthropogenic components beside CO2 (aerosols, other GHGHs, etc.) cancelled one another out so that total anthropogenic forcing = CO2 forcing.

Comparing total forcing and warming is the only sensible approach, but the contribution from aerosols is highly uncertain.

a) that natural forcing represented 7 % of the total forcing b) that all anthropogenic forcing componenets other than CO2 (other GHGs, aerosols, land use changes, etc.) cancelled one another out, so that forcing from CO2 = total anthropogenic forcing c) that the CO2 / temperature relation is logarithmic

But here's the problem: when the concentration of aerosols is reduced — and they have to be; many of them are poisons pure and simple — the total «greenhouse forcing» will rise rapidly unless the non-CO2 gases, as well as soot, are also reduced, and just as quickly.

I found it elsewhere and it shows that if total current aerosol forcing was about -1.0 W / m2 then the best ECS estimate was about 1.7 C. ECS of 3.0 would require a current aerosol forcing of -1.75 W / m2.

According to our best assessments of TSI, aerosols and greenhouse gas concentrations, and ENSO (with SOI as a proxy for the early period) the temperature curve over the whole 20th century is fully consistent with the variation in total forcing + ENSO variability.

IPCC AR4 WG1 tells us that the all anthropogenic forcing components except CO2 (aerosols, other GHGs, land use changes, other changes in surface albedo, etc.) have essentially cancelled one another out, so we can use the estimated radiative forcing for CO2 (1.66 W / m ^ 2) to equate with total net anthropogenic forcing (1.6 W / m ^ 2).

Has any similar analysis been done on the CMIP5 ensemble, to show the correlation (or lack thereof) between estimated ECS, and historical values for total anthropogenic forcing and aerosol forcing?

However the CMIP5 models show no particular correlation between ECS and total forcing or effective aerosol forcing (which includes the indirect effect).

Figure 2 shows the correlation between total anthropogenic forcing and forcing due to tropospheric aerosols.

However, if one converts the total effects of all greenhouse gases, aerosols, etc. into an equivalent increase in CO2 concentration (by reference to their effective radiative forcing RF, that from a doubling of CO2 being F2xCO2), then what you suggest would be pretty much in line with the generic definition of TCR in Section 10.8.1 of AR5 WGI:

PS to my 4:48 AM post: The non-linearity of the TCR estimate to aerosol forcing also means that a 0.49 W / m2 total adjustment would bring the TCR estimate down to about 1.4 °C, not 1.26 °C (which was based on a simple scaling of Shindell's sensitivity analysis).