Sentences with phrase «effect of aerosols from»

Myhre, G., N. Bellouin, T.F. Berglen, T.K. Berntsen, O. Boucher, A. Grini, I.S.A. Isaksen, M. Johnsrud, M.I. Mishchenko, F. Stordal, and D. Tanre, 2007: Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean.

Another source of uncertainty comes from the direct effect of aerosols from human origins: How much do they reflect and absorb sunlight directly as particles?

This is another reason why the effects of aerosols from coal burning were overwhelmed in this period.

Not exact matches

In this paper, UCR and Forest Service researchers teamed up to explore a previously unstudied aspect of nitrogen saturation: its effect on the gases and aerosols released during burning of forest fuels from an area experiencing nitrogen saturation.

Similar scandals erupted over the effects of scores of industrial applications, ranging from sulfur dioxide and acid rain, to certain aerosols and the hole in the ozone layer, to leaded gas and cognitive impairment, to the granddaddy of them all, fossil fuels and global climate change.

The theory of dangerous climate change is based not just on carbon dioxide warming but on positive and negative feedback effects from water vapor and phenomena such as clouds and airborne aerosols from coal burning.

This unique orbit path will allow the CATS instrument to observe locations at different times of day and allow scientists to study day - to - night changes in cloud and aerosol effects from space.

During this event, the aerosols stayed close to the surface due to the presence of a anticyclone hovering over the study region at sea - level, «reducing the amount of shortwave irradiance reaching the surface and causing greater radiative cooling,» states Obregón, who likens the effects of desert dust with those resulting from certain forest fires or episodes of high pollution.

For this reason, a group of researchers from Extremadura (Spain) and Portugal has analysed the radiative effect of a type of natural aerosol (the dust from the desert areas), of great interest to the Iberian Peninsula due to the proximity of the Sahara desert.

But the effect of so - called biogenic aerosol — particulate matter that originates from plants — had been less well understood.

At least over the oceans, the pre-industrial cloud conditions would have been considerably different from those of today; this implies that the aerosols we have been adding to the atmosphere may have had a significant effect on global patterns of cloud formation and rain.

The cooling effect of aerosols can partly offset global warming on a short - term basis, but many are made of organic material that comes from sources that scientists don't fully understand, said Joost de Gouw, a research physicist at NOAA's Earth System Research Laboratory in Boulder, Colo., who is unaffiliated with the studies.

Past calculations of the cooling effect of aerosols have been inferred from «missing» global warming predicted by climate models.

IPCC scientists have suspected for a decade that aerosols of smoke and other particles from burning rainforest, crop waste and fossil fuels are blocking sunlight and counteracting the warming effect of carbon dioxide emissions.

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.

An adjustment is necessary because as climate models are continually evaluated against observations evidence has become emerged that the strength of their aerosol - cloud interactions are too strong (i.e. the models» «aerosol indirect effect» is larger than inferred from observations).

Fascinatingly, the book from the mid-70s said that there was one climate scientist — Wally Broecker - who predicted that the greenhouse warming was on the verge of overtaking the aerosol cooling effects and that by the year 2000 the planet would be warmer than it had been in 1000 years.

The cooling effect from this aerosol forcing is thought to be about half that of greenhouse gases, but in the opposing (cooling) direction.

That's far from the worst flaw in his calculation, since his two biggest blunders are the neglect of the radiative cooling due to sulfate aerosols (known to be a critical factor in the period in question) and his neglect of the many links in the chain of physical effects needed to translate a top of atmosphere radiative imbalance to a change in net surface energy flux imbalance.

Paraphrasing the text in the post, aerosols that are input into the atmosphere, due to their spatial heterogeneity, also cause regions of heating or cooling that the atmosphere can respond to by changing its circulation — and that might have further climate effects in places far away from where the aerosols are input.

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).

Sometimes various factors like aerosols or vegetation change aren't considered, and thus whatever effect they might have would just be lumped into the value of climate sensitivity value that emerges from this method.

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.

Furthermore, APS would have a wider specular range, which would have improved the ability to differentiate aerosols from the effects of ground reflectance.

For example, they predicted the expansion of the Hadley cells, the poleward movement of storm tracks, the rising of the tropopause, the rising of the effective radiating altitude, the circulation of aerosols in the atmosphere, the modelling of the transmission of radiation through the atmosphere, the clear sky super greenhouse effect that results from increased water vapor in the tropics, the near constancy of relative humidity, and polar amplification, the cooling of the stratosphere while the troposphere warmed.

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.

If those aerosols canceled the warming effect of fossil fuel emissions from 1940 - 1979, as has been claimed, then they would have had the same effect prior to 1940, regardless of whether the volume of both CO2 emissions and aerosol emissions were smaller.

My best guess from browsing Chapter 8 of the Physical Science Basis is that given the high uncertainty in the indirect effect on aerosols, the decision was to report GWPs that don't include these effects.

c) anthropogenic aerosols — mainly sulfate and nitrate (from emissions of SO2 and NOx / NH3) have a strong direct effect and undoubted liquid cloud nucleation impacts (the indirect effects).

V 323: If those aerosols canceled the warming effect of fossil fuel emissions from 1940 - 1979, as has been claimed, then they would have had the same effect prior to 1940, regardless of whether the volume of both CO2 emissions and aerosol emissions were smaller.

Research by an international team of scientists recently published in the journal Geophysical Research Letters says that the cooling effect of aerosols is so large that it has masked as much as half of the warming effect from greenhouse gases.

The fraction of the light that scatters back out to space is responsible for the increased albedo and the cooling effect from sulfate aerosols.

The bottom line is that uncertainties in the physics of aerosol effects (warming from black carbon, cooling from sulphates and nitrates, indirect effects on clouds, indirect effects on snow and ice albedo) and in the historical distributions, are really large (as acknowledged above).

But more generally, something I've wondered is: while in the global annual average, aerosols could be said to partly cancel (net effect) the warming from anthropogenic greenhouse forcing, the circulatory, latitudinal, regional, seasonal, diurnal, and internal variability changes would be some combination of reduced changes from reduced AGW + some other changes related to aerosol forcing.

Let's see... many models show that aerosols could have been artificially keeping the world's average surface temperature cooler by about 3 - 5 degrees C from 1900 - 2000 --(sulfate aerosols certainly have some certifiable cooling effects cancelling out the warming effects of CO2).

We know how much radiation comes from the sun, and we know the effects of CO2, but there are pretty large error bars on aerosols that this mission could help with.

Inclusion of calculated indirect effects from aerosols for instance or if unknown / un-included forcings are significant this may lead to more model - obs disagreements.

In other words, if we are after a cause (or causes) for the temperature increase during the period in question, the presence or absence of aerosols from volcanic eruptions is beside the point, because they can not explain any increase in temperatures that occurred prior to any cooling effect they might have had.

The GCM's I know of (and as described by the IPCC 2001) do include a large cooling effect from aerosols.

This assessment is from my own lab and so I may be a little biased, but although there are significant uncertainties (particular for the aerosol indirect effects), it probably gives a reasonable idea of the current thinking.

And for those of you who want to insist that aerosols produced by the uncontrolled burning of coal neutralized the effects of AGW from 1940 to 1979, please explain how the same argument could not be made for the effects of coal - induced aerosols during this earlier period, when no constraints on the polluting effects of coal combustion were present at all.

Victor, if an absence of volcanic aerosols results from their «dissipation» and this in turn results in a «rebound» as you say it does, is not such a «rebound» a «real effect» resulting from an «absence» (or more usually a partial absence) of volcanic aerosols?

And it doesn't help when I'm expected to accept that industrial aerosols balanced the effects of CO2 from 1940 - 1979, yet can be safely ignored when considering the years 1910 - 1940.

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?

And yes, an accumulation of aerosols from previous eruptions can delay the process of aerosol dissipation from the most recent eruption, but the presence of these leftover aerosols only prolongs the cooling effect, no?

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).

From sheer thermal inertia of the oceans, but also because if you close down all coal power stations etc., aerosol pollution in the atmosphere, which has a sizeable cooling effect, will go way down, while CO2 stays high.

Multi-signal detection and attribution analyses, which quantify the contributions of different natural and anthropogenic forcings to observed changes, show that greenhouse gas forcing alone during the past half century would likely have resulted in greater than the observed warming if there had not been an offsetting cooling effect from aerosol and other forcings.

So aerosols that drift up there from Europe likely had a more noticeable cooling effect than in other regions of the world.

The orthodox explanation for that one is that the cooling effect of white aerosols such as sulphates — released from coal and oil burning — was masking the warming effect of greenhouse gases until various clean air acts allowed the anthropogenic warming trend to re-emerge.