Sentences with phrase «smallest aerosol forcing»

The model that is most consistent with the observed evolution has the smallest aerosol forcing.

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).

Increasing evidence of small aerosol forcing supports the importance of internal variability in explaining inter hemispheric differences in temperature variability.

Not exact matches

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.

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.

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.

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).

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..

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).

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 important point here is that a small external forcing (orbital for ice - ages, or GHG plus aerosols & land use changes in the modern context) can be strongly amplified by the positive feedback mechanism (the strongest and quickest is atmospheric water vapor - a strong GHG, and has already been observed to increase.

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.

«Because T1 has no anthropogenic sulphate aerosol (ASA) forcing, its mean (Î 1/4 = 1.43 °C, median m = 1.38 °C) standard deviation (0.35 °C) and skewness (s = 0.80) are small, and its 90 % confidence interval 0.94 °C to 2.04 °C, is narrower and shifted toward smaller values than the IPCC range of 1.5 °C to 4.5 °C.

You can even go one better — if you ignore the fact that there are negative forcings in the system as well (cheifly aerosols and land use changes), the forcing from all the warming effects is larger still (~ 2.6 W / m2), and so the implied sensitivity even smaller!

Even your Wikipedia article from the observations / sensibility post shows a scant 0.1 C warming due to GHGs for the period in question together with a small negative forcing from sulphate aerosols.

Small forcings due to changes in desert dust aerosols and the pseudo-forcing due to changes in stratospheric water vapor might to some extent be non-anthropogenic in nature.

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 accepted forcing series do not include these frequencies (apart from some aerosol fudges which inconsistently explain a small part of the amplitude of variation of the 61 - year oscillation), and so GCMs typically explain all of the late 20th heating with GHG forcing.

2) There are errors in the assumed forcings, such as: a) AR5 let stratospheric aerosol concentration go to zero after 2000 (a sure way to prod the models into higher predictions), but it actually increased for the next 10 years «probably due to a large number of small volcanic eruptions».

I'm talking about an example of a massive, ongoing aerosol forcing over a small area not having any measurable effect on its temperature (at least during the current SH winter).

We used the 1D model to obtain a consensus - supporting climate sensitivity when traditional forcings were used (mostly anthropogenic GHGs, aerosols, and volcanoes), but a much smaller 1.3 deg.

There are postive forcings from BC and TSI in this period but these forcings estimates appear to be small compared to GHG's and aerosols.

Despite potentially large absolute errors in these forcings, their impact on our analysis is likely to be small, as the tropospheric aerosol forcing in the datasets analyzed changed very little over 1985 — 96 (Myhre et al. 2001).»

The key point here is that the range of values of climate sensitivity, and of aerosol forcing are small.

The low estimates of climate sensitivity by Chylek and Lohmann (2008) and Schmittner et al. (2011), ~ 2 °C for doubled CO2, are due in part to their inclusion of natural aerosol change as a climate forcing rather than as a fast feedback (as well as the small LGM - Holocene temperature change employed by Schmittner et al., 2011).»

I should add that as the relationship of estimated TCR to adjusted aerosol forcing is non-linear, the range is smaller on the downside, and a 0.25 W / m ² rather than 0.15 W / m ² increase in Shindell's aerosol forcing adjustment is required to bring his TCR estimate down to 1.35 C.

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.

... «I argue that the current agreement of model simulated and observed warming (given the other forcings) points towards a relatively small total aerosol effect.»

«The overall slow decrease of upwelling SW flux from the mid-1980's until the end of the 1990's and subsequent increase from 2000 onwards appear to caused, primarily, by changes in global cloud cover (although there is a small increase of cloud optical thickness after 2000) and is confirmed by the ERBS measurements... 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.

This linear relationship breaks down for absorbing aerosols, which may have small TOA forcing, but disproportionately larger surface forcing due to absorption of solar radiation (Lohmann and Feichter, 2001; Ramanathan et al., 2001a).

For the «Aerosol - Cloud Interaction» (ACI): There is a recent paper http://onlinelibrary.wiley.com/doi/10.1002/2017GL075280/full which shows that this effect is very small in the real world but models use it «excessive» to generate a big negative aerosol forcing (see fig. 2 of the main arAerosol - Cloud Interaction» (ACI): There is a recent paper http://onlinelibrary.wiley.com/doi/10.1002/2017GL075280/full which shows that this effect is very small in the real world but models use it «excessive» to generate a big negative aerosol forcing (see fig. 2 of the main araerosol forcing (see fig. 2 of the main articel).

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.

So we have the peculiar situation that both of these approaches try to claim that climate sensitivity is small, but the NIPCC approach is to claim that aerosol forcing is very large (thus providing a negative feedback to warming), whereas the Lindzen approach is to claim that aerosol forcing is very small (thus necessitating a small sensitivity to explain the observed warming so far).

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.

To make climate sensitivity small you've got to assume some combination of forcings that is high and temperature increase that is low (ie take the maximum for greenhouse gases, negligible aerosol forcing, maximum solar forcing and the bottom of the temperature range).

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.

The study didn't explore anything like full ranges of key climate parameters: equilibrium climate sensitivities below 2 K were not included in the ensemble, only a limited range of ocean heat uptake levels appears to have been considered, and it is unclear to me to what extent the possibility of aerosol forcing being small was represented.

Judith Curry also mentions assumptions that she's «not entirely comfortable with», and she ends up hedging her bets and saying that your qualititative conclusion seems robust, that lower ECS seems justified by the smaller - ve aerosol forcing.

Figure 4 shows that changes in several external forcings over the ETCW could be important, such as: a greenhouse gas increase, a small change in solar irradiance, and a reduction in stratospheric aerosols associated with reduced volcanic activity.

Clouds are not a forcing of the climate system (except for the small portion related to human related aerosol effects, which have a small effect on clouds).