Sentences with phrase «aerosol forcings on»

Lamarque, D. Olivié, T. Richardson, D. Shindell, and T. Takemura, 2018: A PDRMIP multi-model study on the impacts of regional aerosol forcings on global and regional precipitation.

Not exact matches

Another massive undertaking, the Indian Ocean Experiment (INDOEX), meanwhile, was specifically designed to see if climate forcing on the part of aerosol particles could be directly measured.

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

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).

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).

Therefore studies based on observed warming have underestimated climate sensitivity as they did not account for the greater response to aerosol forcing, and multiple lines of evidence are now consistent in showing that climate sensitivity is in fact very unlikely to be at the low end of the range in recent estimates.

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.

And finally, current theories based on greenhouse gas increases, changes in solar, volcanic, ozone, land use and aerosol forcing do a pretty good job of explaining the temperature changes over the 20th Century.

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.

Most of the non-model estimates of climate sensitivity are based on the analyses using other forcings such as solar and aerosols, and the assumption that sensitivity to CO2 will be the same, despite the differences in way these forcings couple to the climate system.

The top priorities should be reducing uncertainties in climate sensitivity, getting a better understanding of the effect of climate change on atmospheric circulation (critical for understanding of regional climate change, changes in extremes) and reducing uncertainties in radiative forcing — particularly those associated with aerosols.

Until recently, the properties of these aerosols were hard to experimentally characterize, forcing computational models to rely on unsupported assumptions.

-LRB--0.9 W / m2 against -1.3 W / m2) On this link, http://data.giss.nasa.gov/modelforce/RadF.txt, NASA - GISS provides a total aerosol forcing, in 2011, of -1.84 W / m2.

Similarly, Gregory et al. (2002a) apply an inverse estimate of the range of aerosol forcing based on fingerprint detection results.

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.

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.

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.

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).

As long as the temporal pattern of variation in aerosol forcing is approximately correct, the need to achieve a reasonable fit to the temporal variation in global mean temperature and the difference between Northern and Southern Hemisphere temperatures can provide a useful constraint on the net aerosol radiative forcing (as demonstrated, e.g., by Harvey and Kaufmann, 2002; Stott et al., 2006c).

The indirect aerosol effect on clouds is non-linear [1], [76] such that it has been suggested that even the modest aerosol amounts added by pre-industrial humans to an otherwise pristine atmosphere may have caused a significant climate forcing [59].

In addressing the question of the effects of greenhouse gases on Atlantic tropical storms, it might clarify (and even partially defuse) the controversy to lump internal variability together with other forced responses (particularly aerosols), rather than to focus on internal variability vs the total forced response.

They determine the probability of combinations of climate sensitivity and net aerosol forcing based on the fit between simulations and observations (see Section 9.6 and Supplementary Material, Appendix 9.

Forward model approaches to estimating aerosol forcing are based on estimates of emissions and models of aerosol physics and chemistry.

On the other hand, we are also probably underestimating a negative aerosol forcing, e.g., because we have not included future volcanic aerosols.

For the sake of interpreting on - going and future climate change it is highly desirable to obtain precise monitoring of the global aerosol forcing [73].

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.

Judy Curry's blog posted an item on a Richard Lindzen presentation that included the claim that aerosol forcing is adjusted to make climate projections match observed temperature trends.

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.

The prediction of the long - term trajectory, depends on the climate forcing (greenhouse gases, aerosols, solar variability) and how the model responds to those forcings via feedbacks.

In a new review paper in Nature this week, Andreae, Jones and Cox expand on the idea that uncertainty in climate sensitivity is directly related to uncertainty in present day aerosol forcing (see also this New Scientist commentary).

They also demonstrate that there are important dependencies on the ocean heat uptake estimates as well as to the aerosol forcings.

It is my understanding that the uncertainties regarding climate sensitivity to a nominal 2XCO2 forcing is primarily a function of the uncertainties in (1) future atmospheric aerosol concentrations; both sulfate - type (cooling) and black carbon - type (warming), (2) feedbacks associated with aerosol effects on the properties of clouds (e.g. will cloud droplets become more reflective?)

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.

Also, due to the multiplicity of anthropogenic and natural effects on the climate over this time (i.e. aerosols, land - use change, greenhouse gases, ozone changes, solar, volcanic etc.) it is difficult to accurately define the forcings.

I must add on, there are no reasons for the atmosphere as a whole not to warm, no active massive Volcano eruption neither extra sun reflecting aerosols, there is according to some a 1 W / m2 lull in solar forcing at this current solar minima.

The stratospheric component of ECHO - G is obviously better than in an EBM but many of the important factors that lead to this being important were not considered in those runs (i.e. the volcanic forcing was input as an equivalent TOA forcing, rather than as absorbing lower stratospheric aerosols, and no stratospheric ozone feedbacks on the solar forcing were included).

Based on NASA's CMIP5 forcing model, year 2012 has a greenhouse forcing of 3.54 Wm2, ozone has 0.45 Wm2, atmospheric aerosols have -0.89 Wm2 combined direct / indirect, and land use has -0.19 Wm2, all based on iRF.

The portion associated with short term forcings (solar, unaccounted - for volcanic aerosols, undercounts of Chinese pollution) will depend on their long term evolution — if they stabilise, you'd get a delay.

As I said to Andy Revkin (and he published on his blog), the additional decade of temperature data from 2000 onwards (even the AR4 estimates typically ignored the post-2000 years) can only work to reduce estimates of sensitivity, and that's before we even consider the reduction in estimates of negative aerosol forcing, and additional forcing from black carbon (the latter being very new, is not included in any calculations AIUI).

On your page, you show the results for HADCM3 aerosol and ozone (actually the difference between total forcing and GHG forcing, but should be approximately the same).

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.

Therefore studies based on observed warming have underestimated climate sensitivity as they did not account for the greater response to aerosol forcing, and multiple lines of evidence are now consistent in showing that climate sensitivity is in fact very unlikely to be at the low end of the range in recent estimates.

Similarly, the influence of aerosols on precipitation processes is another example of a non-radiative climate forcing (see pages 6, and 42 - 44, for example, in the NRC report).

However, the traditional RF often used now (defined in IPCC 2001, 2007 although deviations from this exist, especially for aerosol evaluations) already incorporates stratospheric adjustment which occurs on timescales of several months and so TOA / tropopause forcings become comparable.

A follow - up question related to where we might lose contact between historical and future is the disproportionate role of aerosols on the asymmetries in climate forcing.

[T] here have now been several recent papers showing much the same — numerous factors including: the increase in positive forcing (CO2 and the recent work on black carbon), decrease in estimated negative forcing (aerosols), combined with the stubborn refusal of the planet to warm as had been predicted over the last decade, all makes a high climate sensitivity increasingly untenable.

Yes, there are physical mechanisms to connect GCM's to aerosol formation — however, GCM's aren't the only forcing on the system.

Aerosols exert a forcing on the hydrological cycle by modifying cloud condensation nuclei, ice nuclei, precipitation efficiency, and the ratio between solar direct and diffuse radiation received.

First, for changing just CO2 forcing (or CH4, etc, or for a non-GHE forcing, such as a change in incident solar radiation, volcanic aerosols, etc.), there will be other GHE radiative «forcings» (feedbacks, though in the context of measuring their radiative effect, they can be described as having radiative forcings of x W / m2 per change in surface T), such as water vapor feedback, LW cloud feedback, and also, because GHE depends on the vertical temperature distribution, the lapse rate feedback (this generally refers to the tropospheric lapse rate, though changes in the position of the tropopause and changes in the stratospheric temperature could also be considered lapse - rate feedbacks for forcing at TOA; forcing at the tropopause with stratospheric adjustment takes some of that into account; sensitivity to forcing at the tropopause with stratospheric adjustment will generally be different from sensitivity to forcing without stratospheric adjustment and both will generally be different from forcing at TOA before stratospheric adjustment; forcing at TOA after stratospehric adjustment is identical to forcing at the tropopause after stratospheric adjustment).

These forcings are spatially heterogeneous and include the effect of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot)[Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]-RRB-, and the role of changes in land use / land cover [e.g., Takata et al., 2009].