Sentences with phrase «strong aerosol forcing»

There is also a fairly large increase in modelled sulfate load over the Tropical North Atlantic from about 1960, which is presumably the main cause of modelled present day strong aerosol forcing off the West African coast, as depicted in Booth et al. figure 4b.

Factoring in findings of: Large methane releases lead to strong aerosol forcing and reduced cloudiness 2011 T. Kurt» en1, 2, L. Zhou1, R. Makkonen1, J. Merikanto1, P. R ¨ ais ¨ anen3, M. Boy1, N. Richards4, A. Rap4, S. Smolander1, A. Sogachev5, A. Guenther6, G. W. Mann4, K. Carslaw4, and M. Kulmala1

Many CMIP5 models (influencing strongly the model mean) have an inherent strong aerosol forcing.

Not exact matches

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.

Moreover, some have argued that a strong aerosol radiative forcing means that the climate sensitivity has to be -LSB-...]

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 me.

If we isolate the ocean for diagnosis, there is a rather short list of suspect forcings and feedbacks (ie changes in shortwave reaching ocean surface possibly from strong negative aerosol feedbacks, net positive rate change in loss of longwave from the ocean (which would have implications for the positive WVF), net positive heat loss through evaporation without balancing compensation (with other implications for positive WVF).

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.

* Stronger than expected negative aerosol forcings * Negative cloud feedback * As yet unknown forcings or feedbacks or both

Finally, we have not yet taken note here of Shindell»14 «Inhomogeneous forcing and transient climate sensitivity» which makes a very strong case not only for the unexpected aerosol loading from China being the culprit for the divergence, but also, unfortunately, for the case that a rather high sensitivity is a logical consequence of that explanation.

Internal variability can not keep GW at bay forever, but a strong enough external forcing could (aerosols, sun, cloud changes, all together, whatever).

Overall forcing at the TOA is negative averaged over all aerosols, but significant atmospheric heating and a net positive TOA forcing is possible for aerosols with a strong black carbon component, and some of this will eventually be transmitted to the surface despite the reduction in surface insolation from the light scattering and absorptive properties of the aerosols.

The way they get the low sensitivity is to assume that the forcing is changing much faster than CO2, implying that the other GHGs have a much stronger effect than aerosols.

So, to answer my own question, the inverse correlation between CS and aerosol forcing isn't as strong, but it's likely not zero.

There is a strong positive correlation between these two quantities with a near 3-fold range in the magnitude of aerosol forcing applied over the 20th century.»

The chapter 9 summary also conceded the discrepancy, but attributed it «to a substantial degree» to natural variability, with «possible» contributions from forcing — mentioning aerosols as well as solar and volcanics — and, «in some models», to too strong a response to greenhouse forcing:

There is medium confidence that this difference between models and observations is to a substantial degree caused by unpredictable climate variability, with possible contributions from inadequacies in the solar, volcanic, and aerosol forcings used by the models and, in some models, from too strong a response to increasing greenhouse - gas forcing.

And yes, the high share of non-absorbing aerosols exerts a strong negative forcing also today.

In addition to reduced aerosol cooling and increased black carbon warming there is the IPCC's new admission of strong evidence for some mechanism of solar forcing substantially stronger than TSI (p. page 7 - 43): «Many empirical relationships have been reported between GCR or cosmogenic isotope archives and some aspects of the climate system (e.g., Bond et al., 2001; Dengel et al., 2009; Ram and Stolz, 1999).

Greenhouse warming that is stronger over land and in the Northern Hemisphere tends to strengthen the monsoon, but increases in planetary albedo over the continent due to aerosol forcing and / or land - use change tend to weaken it.

Moreover, some have argued that a strong aerosol radiative forcing means that the climate sensitivity has to be large in order to still be able to explain the temperature trend of the last 100 years, so they seem to be shooting in their own foot.

The projected radiative - forced increase of extreme surface temperatures and stronger spring barrier for wet season onset (Cook et al., 2010a; Seth et al., 2011) would increase risk of forest fires (Golding and Betts, 2008), although how changes of ENSO, AMO, and aerosols loadings will influence future droughts remain unclear (e.g., Andreae et al., 2005).

In doing so, they must account for the strong inter-hemispheric asymmetry in aerosol forcing in order to not render the analysis useless.

Because of its strong asymmetry between the northern and southern hemispheres, in order to estimate aerosol forcing with any accuracy using inverse methods it is essential to use a model that, at a minimum, resolves the two hemispheres separately.

If the global models are correct in this respect, the implication is that much of the observed recent excess warming of the Atlantic is due either to internal mechanisms (variability in the Atlantic Overturning circulation, for example) or non-greenhouse gas external forcing (e.g. recovery from strong aerosol cooling).

That is, there is still a fair chance that we can «hold the 2 °C line», if strong mitigation of greenhouse gases is combined with the following three actions: (i) a slow, rather than instant, elimination of aerosol cooling, (ii) a directed effort to first remove warming aerosols like black carbon, and (iii) a concerted and sustained programme, over this century, to draw - down excessive CO2 (geo - and bio-engineering) and simultaneously reduce non-CO2 forcings, such that the final equilibrium temperature rise will be lower than would otherwise be expected on the basis of current concentrations.

In fact one point you made 2 posts ago — that the aerosol and indirect aerosol forcings seem fudged to make the curve fit — I think that is a strong possibility.

Anticipating that the influence of the aerosol forcing is strongest for longer term temperature trends in summer, application of the detection and attribution test to the latest observed 50 - y trend pattern of summer temperature yielded statistical consistency with the greenhouse gas - plus - aerosol simulation with respect to both the pattern and amplitude of the signal.

As sulphate aerosol is almost entirely scattering, the surface forcing will be similar or marginally stronger than the RF diagnosed at the TOA.

And there remain strong differences of opinion on the relative importance of AMOC variability and aerosol forcing for the non-monotonic variation of North Atlantic surface temperatures and all the phenomena that we think are affected by it (including hurricanes and African rainfall).