Sentences with phrase «aerosol forcing from»

I predict the calculated aerosol forcing from these models is about to undergo a significant drop.

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.

Inverse estimates of aerosol forcing from detection and attribution studies and studies estimating equilibrium climate sensitivity (see Section 9.6 and Table 9.3 for details on studies).

Similarly (and perhaps relatedly), the magnitude of the change in aerosol forcing from ~ 1975 to present relative to the change in all forcings is much smaller than from pre-ind through present, which I think should make the TCR estimated over that period insensitive to the value of E.

Depending on what you are looking at, it could have a bottom up estimate of aerosol forcing or aerosol forcings from a residual calculation — neither of which really have the range of uncertainty.

Possible candidates are an as - yet - unquantified increase in aerosol forcings from Asian sources.

Not exact matches

Aerosols (soot) keep much of the sun's energy from reaching the surface, which means the monsoon doesn't get going with the same force and takes longer to gather up a head of steam.

One just included the effective influence on temperatures from manmade forces (including greenhouse gases and aerosols, which tend to have a cooling effect), while the second included both manmade and natural ones (including volcanic activity and solar radiation).

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.

Indeed the estimate of aerosol forcing used in the calculation of transient climate response (TCR) in the paper does not come directly from climate models, but instead incorporates an adjustment to those models so that the forcing better matches the assessed estimates from the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC).

Or maybe can the chance distribution of the aerosol forcing (main emissions moved from US / Europe to Asia f.e.) used to reduce the uncertainty of the size of the aerosol forcing or the factor E?

So to adjust from 1750 - 2000 to 1850 - 2000 forcings, one must remove 0.215 W / m ² and also remove the -0.164 W / m ² aerosol forcing, multiplying the latter by it's impact relative to that of well - mixed greenhouse gases (~ 1.5) that gives about -0.25 W / m ².

The red line shows the effective temperature forcing of greenhouse gases and aerosols (converted to CO2), and the blue line shows the forcing from both those manmade sources and natural factors, like solar radiation.

In addition, our deficient understanding of aerosol forcing also hinders our ability to use the modern temperature record to constrain the «climate sensitivity» — the operative parameter in determining exactly how much warming will result from a given increase in CO2 concentration.

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.

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.

The forcing over the last 150 years is around 1.6 W / m2 (including cooling effects from aerosols and land use change) but the climate is not (yet) in equilibirum, and so the full temperature response has not been acheived.

[Response: There's some good thinking here, but I think you may have confused Gavin's discussion of the attempts by Andrae et al to infer climate sensitivity from recent warming with the question of whether there's a different sensitivity coefficient for aerosol vs GHG radiative forcing.

The cooling effect from this aerosol forcing is thought to be about half that of greenhouse gases, but in the opposing (cooling) direction.

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.

(e) Estimated temperature response to anthropogenic forcing, consisting of a warming component from greenhouse gases, and a cooling component from most aerosols.

Only a few estimates account for uncertainty in forcings other than from aerosols (e.g., Gregory et al., 2002a; Knutti et al., 2002, 2003); some other studies perform some sensitivity testing to assess the effect of forcing uncertainty not accounted for, for example, in natural forcing (e.g., Forest et al., 2006; see Table 9.1 for an overview).

Forster and Gregory (2006) estimate ECS based on radiation budget data from the ERBE combined with surface temperature observations based on a regression approach, using the observation that there was little change in aerosol forcing over that time.

Note that while results from fingerprint detection approaches will be affected by uncertainty in separation between greenhouse gas and aerosol forcing, the resulting uncertainty in estimates of the near - surface temperature response to greenhouse gas forcing is relatively small (Sections 9.2.3 and 9.4.1.4).

Table 1 and Figure 15 (2nd panel) of the Supplementary Material show that a wide prior extending from -0.3 to -1.8 W / m ^ 2 (corresponding to the AR4 estimated range) was used for indirect aerosol forcing.

When Aldrin adds a fixed cloud lifetime effect of -0.25 W / m ^ 2 forcing on top of his variable parameter direct and (1st) indirect aerosol forcing, the mode of the sensitivity PDF increases from 1.6 to 1.8.

Natural external forcing also results from explosive volcanism that introduces aerosols into the stratosphere (Section 2.7.2), leading to a global negative forcing during the year following the eruption.

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).

Ice sheet albedo forcing is estimated to have caused a global mean forcing of about — 3.2 W m — 2 (based on a range of several LGM simulations) and radiative forcing from increased atmospheric aerosols (primarily dust and vegetation) is estimated to have been about — 1 W m — 2 each.

Aerosol forcing appears to have grown rapidly during the period from 1945 to 1980, while greenhouse gas forcing grew more slowly (Ramaswamy et al., 2001).

Reduction of the amount of atmospheric CH4 and related gases is needed to counterbalance expected forcing from increasing N2O and decreasing sulfate aerosols.

However, a concerted effort to reduce non-CO2 forcings by methane, tropospheric ozone, other trace gases, and black soot might counteract the warming from a decline in reflective aerosols [54], [75].

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).

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

Human - made tropospheric aerosols, which arise largely from fossil fuel use, cause a substantial negative forcing.

From the Physical Science Basis: «Shindell et al. (2009) estimated the impact of reactive species emissions on both gaseous and aerosol forcing species and found that ozone precursors, including methane, had an additional substantial climate effect because they increased or decreased the rate of oxidation of SO2 to sulphate aerosol.

If you want to assume that aerosols resulting from pollution produced by the burning of fossil fuels were responsible for the cooling evident from 1940 through the late 70's, then you have no reason to claim ANY degree of warming due to CO2 forcing during any earlier period.

I guess the footprint of the regional forcing from sulfate aerosols can be detected in temperature trends, but it's subtle.

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.

Current growth in forcings is dominated by increasing CO2, with potentially a small role for decreases in reflective aerosols (sulphates, particularly in the US and EU) and increases in absorbing aerosols (like soot, particularly from India and China and from biomass burning).

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.

Now if this were the case, changes in the forcing due to reflective aerosols at roughly the beginning of World War II and shortly after the enforcement of the Clean Air Laws in the developed economies might very well explain a transition from one climate mode regime to another — that is, if the climate system is particularly sensitive to changes in forcings.

The global mean aerosol radiative forcing caused by the ship emissions ranges from -12.5 to -23 mW / m ^ 2, depending on whether the mixing between black carbon and sulfate is included in the model.

If you «use all of the data» you can't detect any change in trend from forcings known to make a difference (e.g. sulfate aerosols, which peaked in the 1940 - 1970 range from US sources and again later from Chinese).

These details are not inconsequential because most of the conclusions in their paper stem from the rapid increase in climate sensitivity between 1.0 and 2.0 W / m2 aerosol forcing.

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 me.

[Response: Aerosol forcings in the GISS model are derived from externally produced emission inventories, combined with online calculations of transport, deposition, settling etc..

Given the large and growing (my opinion) uncertainty of the aerosol forcing, how can we make meaningful statements about the climate sensitivity from paleo - experiments?

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.

So the climate sensitivity is itself very sensitive to changes in the negative forcing from aerosols.