Sentences with phrase «aerosol forcing as»

So I've had a closer albeit quick look at the abstracts citing it and I do see one paper by Xu and Ramanathan 2012 GRL that appears to argue for aerosol forcing as the cause of mid century cooling.

This is expressed in the reduction of the uncertainty range for the aerosol forcing as shown in the leaked AR5 SOD.

However, it is clear that ocean variability interferes with aerosol forcing as well as with any other forcing.

The method that Nic is using, and what Forest et al used previously, has aerosol forcing as one of the three free parameters.

In fact, they may do so more efficiently than more uniform temperature change; warming one hemisphere with respect to the other is an excellent way of pulling monsoonal circulations and oceanic ITCZs towards the warm hemisphere (the last few years have seen numerous studies of this response, relevant for ice ages and aerosol forcing as well as the response to high latitude internal variability; Chiang and Bitz, 2005 is one of the first to discuss this, in the ice age context; I'll try to return to this topic in a future post.)

It is rather surprising that adding cloud lifetime effect forcing makes any difference, insofar as Aldrin is estimating indirect and direct aerosol forcings as part of his Bayesian procedure.

It is rather surprising that adding cloud lifetime effect forcing makes any difference, insofar as Aldrin is estimating indirect and direct aerosol forcings as part of his Bayesian procedure.

Not exact matches

The researchers [3] quantified China's current contribution to global «radiative forcing» (the imbalance, of human origin, of our planet's radiation budget), by differentiating between the contributions of long - life greenhouse gases, the ozone and its precursors, as well as aerosols.

Taking factors such as sea surface temperature, greenhouse gases and natural aerosol particles into consideration, the researchers determined that changes in the concentration of black carbon could be the primary driving force behind the observed alterations to the hydrological cycle in the region.

The models, which factor in natural effects such as solar winds and volcanic eruptions, along with anthropogenic forcings like greenhouse gases and aerosols, match these precipitation variations accurately in trend and reasonably well in magnitude.

Radiative forcing, especially that due to aerosols, is highly uncertain for the period 1750 - 1850 as there is little modeling and even less data to constrain those models.

Therefore studies based on observed warming have underestimated climate sensitivity as they did not account for the greater response to aerosol forcing, and multiple lines of evidence are now consistent in showing that climate sensitivity is in fact very unlikely to be at the low end of the range in recent estimates.

The hemispheric responses, in particular in the SH where the imposed aerosol forcing is very small, can be quite sensitive to factors such as how a given model transports heat between the hemispheres, however.

It is important to realize that the results presented in the paper include both the uncertainty in the aerosol forcing and the uncertainty in the enhancement of the response to aerosol forcing, as explicitly stated.

There is a huge offset between aerosols and CO2 sensitivity, as can be seen in Climate sensitivity and aerosol forcings.

The Canadian model suppresses the influence of aerosols in the regional distribution far more, as the direct forcing of GHGs increases to 3.3 and 5.8 W / m2 for resp.

Forcing changes of similar magnitude, due to water vapour variations, are measurable as regional temperature changes in Europe, see Philipona, but aerosol changes are not...

This shows that the temperature response, even to a geographically defined forcing such as aerosols, shows little overlap with the spatial pattern of forcing itself — although of course there is some overlap.

If you set the aerosol forcing to zero you don't get the mid-century interruption of warming, and if the aerosol forcing were allowed to get as big as, say, 10 W / m ** 2 you would get excessive cooling unless you imposed a very low climate sensitivity — which would then make it impossible to reproduce the post-1970's warming.

Most of the non-model estimates of climate sensitivity are based on the analyses using other forcings such as solar and aerosols, and the assumption that sensitivity to CO2 will be the same, despite the differences in way these forcings couple to the climate system.

Since climate scientists certainly don't have a crystal ball, we generally take a range of scenarios or projections of future emissions of CO2 and other important forcings such as methane and aerosols.

Most studies consider a range of anthropogenic forcing factors, including greenhouse gases and sulphate aerosol forcing, sometimes directly including the indirect forcing effect, such as Knutti et al. (2002, 2003), and sometimes indirectly accounting for the indirect effect by using a wide range of direct forcing (e.g., Andronova and Schlesinger, 2001; Forest et al., 2002, 2006).

Knutti et al. (2002) also determine that strongly negative aerosol forcing, as has been suggested by several observational studies (Anderson et al., 2003), is incompatible with the observed warming trend over the last century (Section 9.2.1.2 and Table 9.1).

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.

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., 2006cAs 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., 2006cas 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., 2006cas demonstrated, e.g., by Harvey and Kaufmann, 2002; Stott et al., 2006c).

In addition, both internal variability and aerosol forcing are likely to affect tropical storms in large part though changes in ocean temperature gradients (thereby changing ITCZ position and vertical shear), while greenhouse gases likely exert their influence by more uniformly changing ocean and tropospheric temperatures, so the physics of the problem may suggest this decomposition as more natural as well.

One type of inverse method uses the ranges of climate change fingerprint scaling factors derived from detection and attribution analyses that attempt to separate the climate response to greenhouse gas forcing from the response to aerosol forcing and often from natural forcing as well (Gregory et al., 2002a; Stott et al., 2006c; see also Section 9.4.1.4).

However, such model studies can not provide definite answers, as there is a range of possible model outcomes because the solar forcing is just one of several forcings (e.g. aerosols, greenhouse gases, land surface) that are not well - constrained by observations.

Note too that the details of how aerosols are implemented in any specific model can also make a difference to the forcing, and there are many (as yet untested) assumptions built into the forcing reconstructions.

Lewis» argument up until now that the best fit to the transient evolution over the 20th Century is with a relatively small sensitivity and small aerosol forcing (as opposed to a larger sensitivity and larger opposing aerosol forcing).

Firstly the forcings over this period are not as well known as in more recent times (solar, aerosols, especially black carbon).

This has been partly masked by a negative human aerosol forcing so far, but that masking will likely become smaller as more people will demand cleaner air.

They also demonstrate that there are important dependencies on the ocean heat uptake estimates as well as to the aerosol forcings.

I must add on, there are no reasons for the atmosphere as a whole not to warm, no active massive Volcano eruption neither extra sun reflecting aerosols, there is according to some a 1 W / m2 lull in solar forcing at this current solar minima.

As an aside, the radiative forcing by aerosols (in both long wave and solar radiation at the tropopause) is not the same as global dimming (which is a solar radiation effect at the surface) though they are relateAs an aside, the radiative forcing by aerosols (in both long wave and solar radiation at the tropopause) is not the same as global dimming (which is a solar radiation effect at the surface) though they are relateas global dimming (which is a solar radiation effect at the surface) though they are related.

Of course, this assumes a few things, such as that levels of other GHGs, such as methane, are returned to their pre-industrial levels, or continue to be counter-balanced by aerosol forcings.

However, the fundamental point which underlies all their calculations is the link between aerosol forcing and sensitivity, which I would argue is not as strong as they have posited.

As well as effective aerosol forcing of -1.2 W / m2 being mcuh stronger than the IPCC AR5 ERF of ~ -0.7 W / m2 over 1850 - 2000, the land use change effective forcing of -0.7 W / m2, arsign from a very high efficacy of 3.89, seems absurd to mAs well as effective aerosol forcing of -1.2 W / m2 being mcuh stronger than the IPCC AR5 ERF of ~ -0.7 W / m2 over 1850 - 2000, the land use change effective forcing of -0.7 W / m2, arsign from a very high efficacy of 3.89, seems absurd to mas effective aerosol forcing of -1.2 W / m2 being mcuh stronger than the IPCC AR5 ERF of ~ -0.7 W / m2 over 1850 - 2000, the land use change effective forcing of -0.7 W / m2, arsign from a very high efficacy of 3.89, seems absurd to me.

This is a peer reviewed paper by respected scientists who are saying that aerosol forcing means that the majority of the warming caused by existing co2 emission has effectively been masked thus far, and that as aerosols remain in the atmosphere for far shorter a duration of time than co2, we will have already most likely crossed the 2 degree threshold that the G8 politicians have been discussing this week once the cooling effect of aerosols dissipate.

The stratospheric component of ECHO - G is obviously better than in an EBM but many of the important factors that lead to this being important were not considered in those runs (i.e. the volcanic forcing was input as an equivalent TOA forcing, rather than as absorbing lower stratospheric aerosols, and no stratospheric ozone feedbacks on the solar forcing were included).

Given that you comment that the largest differences between the different forcings is between land and ocean or between the Northern and Southern Hemispheres, have you looked at the land — ocean temperature difference or the Northern — Southern Hemisphere temperature difference, as they both scale linearly with ECS, in the same way as global mean temperature for ghg forcing, but not for aerosol forcing.

Except that GHG forcing + cooling aerosol forcing results in less precipitation globally in general than reduced GHG forcing that produces the same global average temperature, as found in «Climate Change Methadone» elsewhere at RC.

I can't tell how they've accounted for natural removal by the oceans, and they do assume other forcings (such as cooling from aerosols) are removed.

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.

But there are offsets between GHGs / aerosol combinations and solar activity (especially as derived by Hoyt and Schatten), which may have been underestimated (see Stott e.a. 2003) If one simply should compare only the influence of solar (by H&S or even LBB) with the increase in heat content of the oceans, one can get a similar conclusion: that solar is the main driving force in ocean heat content.

As I said to Andy Revkin (and he published on his blog), the additional decade of temperature data from 2000 onwards (even the AR4 estimates typically ignored the post-2000 years) can only work to reduce estimates of sensitivity, and that's before we even consider the reduction in estimates of negative aerosol forcing, and additional forcing from black carbon (the latter being very new, is not included in any calculations AIUI).

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.

As I see it, your confusion is best revealed in the following sentence: «you have temperature dropping when aerosol forcing increases from 2 to (let's say) 8, then rising again as the aerosols clear.&raquAs I see it, your confusion is best revealed in the following sentence: «you have temperature dropping when aerosol forcing increases from 2 to (let's say) 8, then rising again as the aerosols clear.&raquas the aerosols clear.»