Sentences with phrase «net aerosol forcing»

The situation as I see it is opposite: Mainstream science acknowledges there is a large uncertainty in the net aerosol forcing, whereas Lindzen picks onevalue at the outer edge of the probability distribution function and builds his entire argument on that (rather improbable) value as if it's highly certain: His argument is implicitly built on high confidence / certainty that aerosol forcing is very low.

Likely no net aerosol forcing effect.

What is clear is that although the net aerosol forcing is indeed an important determinant of the uncertainty, it is not overwhelming.

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.

By scaling spatio - temporal patterns of response up or down, this technique takes account of gross model errors in climate sensitivity and net aerosol forcing but does not fully account for modelling uncertainty in the patterns of temperature response to uncertain forcings.

They determine the probability of combinations of climate sensitivity and net aerosol forcing based on the fit between simulations and observations (see Section 9.6 and Supplementary Material, Appendix 9.

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.

Aerosol forcings are substantially a result of fossil fuel burning [1], [76], but the net aerosol forcing is a sensitive function of various aerosol sources [76].

Not exact matches

The basic comparison should be with the net forcing (around 1.8 W / m2 from GHG, solar, aerosols etc.) and the 0.02 W / m2 from thermal pollution.

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.

While a relatively minor part of the overall aerosol mass, changes in the anthropogenic portion of aerosols since 1750 have resulted in a globally averaged net radiative forcing of roughly -1.2 W / m2, in comparison to the overall average CO2 forcing of +1.66 W / m2.

Now if this was the 1980s they might have had a point, but the fact that aerosols are an important climate forcing, have a net cooling effect on climate and, in part, arise from the same industrial activities that produce greenhouse gases, has been part of mainstream science for 30 years.

In addition, researchers calculated the changes in the shortwave and longwave and net radiation between the pre-industrial simulation and the present - day simulations to estimate the radiative forcing resulting from the aerosol effects on cirrus clouds.

Thus to provide the clearest picture of the CO2 effect, we approximate the net future change of human - made non-CO2 forcings as zero and we exclude future changes of natural climate forcings, such as solar irradiance and volcanic aerosols.

As long as the temporal pattern of variation in aerosol forcing is approximately correct, the need to achieve a reasonable fit to the temporal variation in global mean temperature and the difference between Northern and Southern Hemisphere temperatures can provide a useful constraint on the net aerosol radiative forcing (as demonstrated, e.g., by Harvey and Kaufmann, 2002; Stott et al., 2006c).

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).

Even more, the net forcing isn't very accurately known either, mainly because of the uncertainties in aerosol forcing.

To be simplistic about it, if the ratio of aerosols (from all sources) to greenhouse gasses (from all sources) increased, then surely the net forcing would decline.

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.

But more generally, something I've wondered is: while in the global annual average, aerosols could be said to partly cancel (net effect) the warming from anthropogenic greenhouse forcing, the circulatory, latitudinal, regional, seasonal, diurnal, and internal variability changes would be some combination of reduced changes from reduced AGW + some other changes related to aerosol forcing.

If we isolate the ocean for diagnosis, there is a rather short list of suspect forcings and feedbacks (ie changes in shortwave reaching ocean surface possibly from strong negative aerosol feedbacks, net positive rate change in loss of longwave from the ocean (which would have implications for the positive WVF), net positive heat loss through evaporation without balancing compensation (with other implications for positive WVF).

The basic comparison should be with the net forcing (around 1.8 W / m2 from GHG, solar, aerosols etc.) and the 0.02 W / m2 from thermal pollution.

«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.

We can derive the underlying trend related to external forcings from the GCMs — for each model, the underlying trend can be derived from the ensemble mean (averaging over the different phases of ENSO in each simulation), and looking at the spread in the ensemble mean trend across models gives information about the uncertainties in the model response (the «structural» uncertainty) and also about the forcing uncertainty — since models will (in practice) have slightly different realisations of the (uncertain) net forcing (principally related to aerosols).

It is virtually certain that anthropogenic aerosols produce a net negative radiative forcing (cooling influence) with a greater magnitude in the NH than in the SH.

Right now, and into the foreseeable future, the net forcing forcing is positive, but its GHGs — aerosols, and the aerosols are complicated, since their forcing depends on location.

Jim D» in Lewis's article at Bishop Hill, he assumes the net forcing is 2.09 W / m2, with CO2, other GHGs, other forcings and aerosols all included.

Furthermore, if we are trying to explain why the rate of warming went up in say 1975 we don't want to look at just the rate of change in forcing due to well - mixed greenhouse gases and reflective aerosols by the rate of change in net forcing.

But during times of recession aerosols fall out, greenhouse gases remain in the atmosphere and heat is accumulated due to net positive forcing.

DK12 compounded their erroneous analysis by attempting to calculate the net climate feedback based solely on their estimated 2002 - 2008 OHC increase for the uppermost 700 meters, and only considering the CO2 and solar radiative forcings, ignoring the significant aerosol forcing, for example.

Since 1975 aerosols and their cooling have declined, but greenhouse - gas forcing has continued to increase, therefore dominating any counterbalance and leading to net (and rapid) warming.]

Now, let's take a case such that the aerosols have a big effect, so that the net forcings are much smaller than the median estimate.

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

It is unclear that net forcing by aerosols is negative — but it is clear that these can be managed with reduced burning of biomass and off the shelf technologies.

For changes from 1861 - 1900 to 1957 - 1994, with non-aerosol forcing change = 1.41: ocean heat change 0.08 (new Levitus data): temperature change = 0.31 it computes aerosol forcing = -0.42 for a net forcing of 0.99 and a computed climate sensitivity of 1.3.

The first column has the net radiative forcing (warming or cooling tendency), and the other columns show the breakdown according to aerosol source.

Well it's even more complex than that because the net warming from humans doesn't just involve CO2, but other greenhouse gases and it factors in the cooling effect of aerosols being dwarfed by the CO2 forcing.

(PS — I don't remember my entire comment, but part of it had to do with the fact that in dividing up attribution for the forcings responsible for post-1950 warming, uncertainties regarding anthropogenic sulfate aerosols are not particularly important, because their net cooling effect wouldn't influence the percentage apportionment among the warming factors)

Schematic diagram of human - made climate forcings by greenhouse gases, aerosols, and their net effect.

Overall forcing at the TOA is negative averaged over all aerosols, but significant atmospheric heating and a net positive TOA forcing is possible for aerosols with a strong black carbon component, and some of this will eventually be transmitted to the surface despite the reduction in surface insolation from the light scattering and absorptive properties of the aerosols.

Irrespective of what one thinks about aerosol forcing, it would be hard to argue that the rate of net forcing increase and / or over-all radiative imbalance has actually dropped markedly in recent years, so any change in net heat uptake can only be reasonably attributed to a bit of natural variability or observational uncertainty.

Note that Lindzen's assumed zero net aerosol + black carbon forcing is outside of this confidence range; therefore, neglecting its effect can not be justified.

Again, you are claiming that your construction of the net forcings over this period is better than the published ones, but you do not seem to be making reference to any of the published papers to challenge their methodology and, as TC and Bob have pointed out, ignored important factors in aerosols.

AR5 (as Nic Lewis regularly points out) concludes a most likely net aerosol offset of -0.9 watt / M ^ 2, which is bizarrely inconsistent with the average level of aerosol offsets used by the AR5 climate model ensemble (much higher offsets in the models), and most consistent with a fairly low (< 2C per doubling) climate sensitivity to forcing.

Our current climate is being warmed by increased GHG's, which represent a greater net positive forcing than either anthropogenic or natural aerosols, or the current rather sleepy sun.

Thus Ramanathan and Carmichael find that the net radiative forcing from aerosols + black carbon is approximately -1.4 W / m2.

The IPCC AR4 report says anthropogenic aerosols are a net negative forcing (just like volcanic aerosols).

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).

IPCC gas told us that since 1750 the net impact of all anthropogenic forcing factors other than CO2 (including aerosols, other GHGs.

The inset in Figure 2d shows the individual greenhouse gases, tropospheric aerosols and the land surface plus snow albedo components that combine to give the net anthropogenic forcing.