Sentences with phrase «estimated effects of aerosols»

The largest uncertainty in that comparison comes from the estimated effects of aerosols in the atmosphere, which can variously shade Earth or warm it.

Not exact matches

Scientists believe that aerosols exert an influence on climate roughly equal to that of greenhouse gases, but the current estimate of aerosols» climate effect carries a large margin of error.

This mis - representation and can have significant ramifications for estimating the direct and indirect effects of aerosols on climate.

To provide guidance for future high - resolution simulations, Dai et al. used a computationally cheaper, two - dimensional chemical transport model to systematically estimate the effects of injecting sulfur dioxide and sulfate aerosols at a range of altitudes, latitudes, and time frames for 62 separate scenarios.

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).

Aldrin et al produce a number of (explicitly Bayesian) estimates, their «main» one with a range of 1.2 ºC to 3.5 ºC (mean 2.0 ºC) which assumes exactly zero indirect aerosol effects, and possibly a more realistic sensitivity test including a small Aerosol Indirect Effect of 1.2 - 4.8 ºC (mean 2aerosol effects, and possibly a more realistic sensitivity test including a small Aerosol Indirect Effect of 1.2 - 4.8 ºC (mean 2Aerosol Indirect Effect of 1.2 - 4.8 ºC (mean 2.5 ºC).

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.

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.

They also compared global estimates of aerosol effects on the Earth's climate using two of the parameterizations.

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.

What that paper does is estimate the effect of El Nino, volcanic aerosols, and solar variations on global temperature.

There is very high confidence that the net 20th C aerosol effect was a cooling — mostly because estimates of tropospheric sulphate aerosols dominate the changes, and because BC and OC changes for many sources almost balance out.

The top panel shows the direct effects of the individual components, while the second panel attributes various indirect factors (associated with atmospheric chemistry, aerosol cloud interactions and albedo effects) and includes a model estimate of the «efficacy» of the forcing that depends on its spatial distribution.

This imbalance is really an important quantity — estimates of how much warming is in the «pipeline», the size of the aerosol cooling effect etc. all depend on knowing what this number is.

But aren't these way too low, since LOTI shows we are — as of 2017 — already around 0.95 C warmer than the 1951 - 1980 average, and there is more warming «in the pipeline» because of the time lag, and another (estimated) 0.5 C warming when the anthropogenic aerosols dimming effect is removed?

Your estimates of climate sensitivity come from the IPCC, which assumes that aerosols will continue to provide a very strong cooling effect that offsets about half of the warming from CO2, but you are talking about time frames in which we have stopped burning fossil fuels, so is it appropriate to continue to assume the presence of cooling aerosols at these future times?

Constraining the influence of natural variability to improve estimates of global aerosol indirect effects in a nudged version of the Community Atmosphere Model 5.

The effect on global - mean temperature of assuming a large value for indirect aerosol forcing (viz. − 1.8 W / m2 in 2005, the 95th percentile value according to the IPCC AR4) compared with temperatures for the central indirect forcing estimate (− 0.7 W / m2) and a less extreme maximum of − 1.1 W / m2.

A new simulation that considers chemical interactions between various gases and atmospheric aerosols is giving scientists and policy makers better estimates of the climate - altering effects of those gases, scientists report.

Forcing estimates for the direct effect of sulphate aerosols and other trace gases included in the DDC models are given in Chapter 6.

The respondents» quantitative estimate of the GHG contribution appeared to strongly depend on their judgment or knowledge of the cooling effect of aerosols.

Climate scientist Kevin Trenberth also notes that the change in the estimated aerosol forcing is mainly associated with indirect aerosol effects, but half of GCMs don't include these indirect effects, and those that do actually tend to simulate less warming.

However, the GWPF report only references the «main results» of Aldrin et al. (2012), whose study actually estimated equilibrium climate sensitivity of about 2.5 or 3.3 °C when accounting for cloud and indirect aerosol effects.

«Between the Fourth and Fifth [IPCC] Assessment Reports the best estimate of the cooling effect of aerosol pollution was greatly reduced.

A) a better temperature record (C&W or berkeley) both of which will increase the numerator (that thing on the top) B) a better OHC record (see the recent paper on sea level which will effect their estimates of OHC (the denominator thing) C) revised forcing due to aerosols from small volcanos.

-- Incorporation of more aerosol species and improved treatment of aerosol - cloud interactions allow a best estimate of the cloud albedo effect.

The total CO2 equivalent (CO2 - eq) concentration of all long - lived GHGs is currently estimated to be about 455 ppm CO2 - eq, although the effect of aerosols, other air pollutants and land - use change reduces the net effect to levels ranging from 311 to 435 ppm CO2 - eq (high agreement, much evidence).

This means that volcanic aerosols have minimal long - term cooling effects and therefore, the warming effect of CO2 has to be much lower than assumed in Hansen's climate models and thus climate sensitivity estimates must be lowered even further.

The effects of aerosols and landuse changes reduce radiative forcing so that the net forcing of human activities is in the range of 311 to 435 ppm CO2 - eq, with a central estimate of about 375 ppm CO2 - eq.»

I know that aerosols are a complicated issue but frankly speaking, I think that the IPCC estimate for the direct effect of aerosols (+0.5 Wm2) is also too high.

Furthermore, estimating the direct and indirect aerosol effects (29) through 2008 as a residual from the Earth's energy balance (as was done for 1954 — 2000) would generate results that either support or contradict the increased importance of anthropogenic sulfur emissions discussed above.

Microphysical theories regarding CR - cloud links via ion - mediated nucleation are well developed, and several studies have attempted to incorporate these effects within atmospheric models to estimate the magnitude of potential affects to aerosols and clouds.

The absorbing effect of organic aerosols is thus implicitly included in the BC estimate, although to an unknown extent.

I gave a calculation of the effects on my ECS estimate of substituting the main composite SOD aerosol adjusted forcing estimate of -0.9 W / m ^ 2 for its satellite - derived estimate, along with James's suggestion of a 30 year OHU trend, in my 2/2/13 5:59 am comment.

Lindzen isn't highlighting that the large uncertainty in aerosol effects is responsible for much of the uncertainty in climate sensitivity estimates: he's making an unjustified claim that the aerosol negative forcing is small.

They are referring to a 1971 article written by climatologist Stephen Schneider, in which he did, indeed, make that prediction; however, as he himself now acknowledges, new evidence soon followed its publication that suggested that 1) the cooling impact of aerosols was not nearly as high as originally estimated and 2) there were many other gases in the atmosphere, including methane, CFCs and ozone, that had the same warming effect as carbon dioxide.

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.

shows that natural VOC induced aerosols above the boundary layer are mostly of natural origin (7:1), and comprise a 2:1 up to > 10:1 amount, compared to SOx (SO2 + sulfate) aerosols in the 0.5 - 10 km free troposphere, or 10 % of the total aerosol optical depth measured by satellites... Add to that the effect below the boundary layer and the effect of other natural aerosols (natural fires, sea salt, sand dust, DMS, NOx), good for some 38 % of the < 1 micron fraction of total aerosols (according to IPCC estimates)...

There are only a handful of published estimates for total anthropogenic aerosol forcing, including first indirect and cloud lifetime effects.

A spring 2003 workshop of top atmospheric scientists in Berlin concluded that the shielding effect of aerosols may be far greater than previously estimated.

The estimated warming of 2.4 °C is the equilibrium warming above preindustrial temperatures that the world will observe even if GHG concentrations are held fixed at their 2005 concentration levels but without any other anthropogenic forcing such as the cooling effect of aerosols.

If we add in the warming effects of the other long - lived greenhouse gases, the best estimate rises to 1.22 °C surface warming caused by human emissions (we've only observed ~ 0.8 °C warming because much of that has been offset by human aerosol emissions).

After the adjustments noted above for latent heat and better accounting for the effects of aerosols and water vapor in the ASR, the revised estimates are 333 and 63 W m − 2 for the downward and net surface LW.

This last result indicates the importance of reducing the uncertainty in the estimate of aerosol forcing, particularly the indirect effects.