Sentences with phrase «large aerosol forcing»

That report relies on studies that include the large aerosol forcing uncertainty, so criticizing my paper for that would be inconsistent.

This actually widens the error bars so much that for large aerosol forcings, you can not rule out even zero climate sensitivity.

As described in Suzuki et al 2013, the value of the parameter that provides the best fit is not the one preferred by comparing directly to cloud observations; the settings that result in larger aerosol forcing seem more justifiable at face value.

Not exact matches

Lewis then argues that the large uncertainty ranges in E and in aerosol forcing make it the TCR estimates «worthless».

If the present forcing is large, the warming due to aerosol decline willl be larger, and conversely.

Does this factor E > 1 mean only a faster response to the aerosol forcing an hence a larger TCR under the same ECS?

The problem with this test is exactly the restraint of a fixed aerosol forcing trend and a fixed sensitivity... without that, the adjustment for solar at one side and GHGs / aerosols at the other side might have been much larger, while maintaining the same (or better) result.

You can also see the relative uncertainty between forcings (e.g., it is much larger for aerosols than for GHGs).

If the negative aerosol forcing were very large, then the cumalative forcing might only be a few tenths of a Watts per square meter, and it would require a rather high sensitivity to explain the observed trend.

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.

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).

And finally, the CMIP5 climate models used values of aerosol forcing that are now thought to be far too large.

(This large uncertainty essentially due to the uncertainty in the aerosol forcing; it is also the main reason why the magnitude of global dimming has little or no implication for climate sensitivity).

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?

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.

If aerosols and GHGs have a lower forcing, that must be compensated by a larger forcing for something else, to fit past temperature trends (especially the 1945 - 1975 period and other — little — ice ages).

The problem with this test is exactly the restraint of a fixed aerosol forcing trend and a fixed sensitivity... without that, the adjustment for solar at one side and GHGs / aerosols at the other side might have been much larger, while maintaining the same (or better) result.

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!

There are various possible explanations for this discrepancy, but it is interesting to speculate that it could indicate that the models employed may have a basic inadequacy that does not allow a sufficiently strong AO response to large - scale forcing, and that this inadequacy could also be reflected in the simulated response to volcanic aerosol loading.

In terms of the aerosols: If you want to argue really simplistic, you could still explain what is seen in Dave's NH - SH time series: due to the larger thermal inertia of the SH, you would expect slower warming there with greenhouse gas forcing, so an increase in NH - SH early on, which would then be reduced as aerosol forcing becomes stronger in the NH.

«Because of the large uncertainty we have in the radiative forcing of aerosols, there is a corresponding large uncertainty in the degree of radiative forcing overall», Crozier said.

It's certainly a large black box if one must rely on my knowlege of the existing data about the role of aerosols in forcing.

«Large Differences in Tropical Aerosol Forcing at the Top of the Atmosphere and Earth's Surface.»

However, detection and attribution analyses based on climate simulations that include these forcings, (e.g., Stott et al., 2006b), continue to detect a significant anthropogenic influence in 20th - century temperature observations even though the near - surface patterns of response to black carbon aerosols and sulphate aerosols could be so similar at large spatial scales (although opposite in sign) that detection analyses may be unable to distinguish between them (Jones et al., 2005).

The climate models have an aerosol forcing that is too large.

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.

I think in fact Hansen would acknowledge this, but has stated that a larger negative aerosol forcing is responsible.

If the aerosol effect is too large, then it is inferred that the model response to GHG forcing is also too large.

Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change.

Well, there is a larger than I expected imbalance in aerosol forcing by hemisphere.

Since the last ~ 17 years is the only period with known low volcanic forcing and since aerosol forcing is one of the largest unknowns, that makes the last 17 years the longest useful period of that type.

(6) The IPCC Diagram of Radiative Forcings has no component for the warming caused by the removal of SO2 aerosols from the atmosphere, and is therefore essentially useless, since the warming due to SO2 aerosol removal is so large.

«The second largest human - made forcing is probably atmospheric aerosols, although the aerosol forcing is extremely uncertain3, 4.

«Since 1997, when Pinatubo's aerosol settled out, the stratosphere has been exceptionally clear... Half or more of the warming since 1995 may due to the lack of large volcanic eruptions... That's about 0.13 °C... The remaining climate change is presumably caused by other forces, such as solar variability, El Nino, Atlantic AMO warming in 1995, lower Albedo and maybe even a little greenhouse gas.»

One is that the IPCC forcing central estimate is 40 % larger than that from CO2 alone since 1950 (due to other GHGs and possibly reduced aerosol impacts relative to previous reports), so if you are going to use CO2 alone, you should really add this other 40 % to match what has happened since 1950 and that is what they did.

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».

Taking this into account will lead to large changes in estimates of the magnitude and spatial distribution of aerosol forcing.

These forcing factors constitute additional elements that could drive variability in the future, particularly volcanic aerosols following large eruptions [59,60].

Given this large (negative) aerosol forcing, precise monitoring of changing aerosols is needed [73].

In short, Lindzen's argument is that the radiative forcing from aerosols is highly uncertain with large error bars, and that they have both cooling (mainly by scattering sunlight and seeding clouds) and warming (mainly by black carbon darkening the Earth's surface and reducing its reflectivity) effects.

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).»

In fact Andrew Dessler and other climate scientists have made this point, that the «instrumental» method uncertainties are too large to tightly constrain climate sensitivity, because of the uncertain aerosol forcing, among othe reasons.

Consequently this counterintuitive result is possible provided the variation the aerosol forcing is large (relative to that range), which it is.

If aerosol forcings turn out to be large, then

and «no data or computer code appears to be archived in relation to the paper» and «the sensitivity of Shindell's TCR estimate to the aerosol forcing bias adjustment is such that the true uncertainty of Shindell's TCR range must be huge — so large as to make his estimate worthless» and the seemingly arbitrary to cherry picked climate models used in Shindell's analysis.

When they define sensitivity or human contribution only with respect to their estimated forcings, it is implied that these are correct, but we know that the uncertainty with respect to clouds, aerosols, etc is large.

This aerosol driven increase in energy reaching the surface is much larger than any increase caused by GHGs during that same 11 year period: a potential aerosol driven forcing of 3.4 to 5 watts / M ^ 2.

Regional effects of aerosol forcing are large; regional mean values of anthropogenic aerosol radiative forcing can be factors of 5 to 10 higher than the global mean values of 0.5 to 1.5 W m − 2 (IPCC, 2001).

Kiehl et al. (2000) improve the treatment of relative humidity compared to Kiehl and Briegleb (1993) and Kiehl and Rodhe (1995) by improving the relative humidity dependence of the aerosol optical properties and by using interactive GCM relative humidities rather than monthly mean ECMWF analyses, resulting in a larger normalised radiative forcing.

The critique of Shindell & Faluvegi 2009 is also without merit, where it states: A second does not estimate aerosol forcing over 90S — 28S, and concludes that over 1976 — 2007 it has been large and negative over 28S — 28N and large and positive over 28N — 60N, the opposite of what is generally believed.