Sentences with phrase «stratospheric volcanic aerosol»

El Nino intensity and frequency increase during solar minima because negative NAO / AO increases, and major stratospheric volcanic aerosol events increase, also increasing El Nino conditions.

Recently I have been looking at the climate models collected in the CMIP3 archive which have been analysed and assessed in IPCC and it is very interesting to see how the forced changes — i.e. the changes driven the external factors such as greenhouse gases, tropospheric aerosols, solar forcing and stratospheric volcanic aerosols drive the forced response in the models (which you can see by averaging out several simulations of the same model with the same forcing)-- differ from the internal variability, such as associated with variations of the North Atlantic and the ENSO etc, which you can see by looking at individual realisations of a particular model and how it differs from the ensemble mean.

It's unwise to point to polar amplification in either hemisphere as «evidence» that anthropogenic and / or stratospheric volcanic aerosols have neither regional nor global effects.

The AOGCMs in the ensemble include many species that are not specified or constrained by the SRES scenarios, including ozone, tropospheric non-sulphate aerosols, and stratospheric volcanic aerosols.

Not exact matches

Now, research suggests that for the past decade, such stratospheric aerosols — injected into the atmosphere by either recent volcanic eruptions or human activities such as coal burning — are slowing down global warming.

Besides SSCE, scientists have also been investigating stratospheric sulfur injections — firing sun - reflecting aerosols into the air, similar to the cooling effect after a volcanic eruption — and cirrus cloud thinning, where you thin the top level of clouds, which have a warming effect on the planet.

Recent measurements demonstrate that the «background» stratospheric aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions.

Geoengineering activities are mimicked in the models by modifying the volcanic aerosol radiative inputs, applied as variations in stratospheric optical depth over four zonal bands bounded by the equator, 30degreesN and 30degreesS.

``... While [ozone depleting substance] ODS levels remain high, a large stratospheric sulfuric aerosol enhancement due to a major volcanic eruption or geoengineering activities would result in a substantial chemical depletion of ozone over much of the globe.»

In the troposphere, major volcanic events have a strong cooling effect, as stratospheric aerosols reflect away some incoming solar radiation before it enters the troposphere.

Volcanic activity is indicated by Stratospheric Aerosol forcing in the link below.

There may be reason to strongly suspect that in any sufficiently complicated dynamical system model (such as climate) with stochastic parameters (e.g., exactly when and where a lightning strike starts a major wildfire or a major submarine earthquake perturbs ocean circulation in a region or a major volcanic eruption introduces stratospheric aerosols), it is almost certain that any given run of the model will have periods of significant deviation from the mean of multiple runs.

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).

There is no right answer for this, since we lack any basis to forecast whether a volcanic eruption will happen and what it's contribution to stratospheric aerosols will be.

The «lack of volcanic activity» has allowed the stratospheric aerosols responsible for such forcing to «dissipate» through the 1930s & 1940s.

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).

Since aerosols last much longer in the stratosphere than they do in the rainy troposphere, the amount of aerosol - forming substance that would need to be injected into the stratosphere annually is far less than what would be needed to give a similar cooling effect in the troposphere, though so far as the stratospheric aerosol burden goes, it would still be a bit like making the Earth a permanently volcanic planet (think of a Pinatubo or two a year, forever).

REMOVING THE LINEAR EFFECTS OF ENSO AND VOLCANIC AEROSOLS HELP TO SHOW THE TIMING OF THE WARMING Many papers and blog posts that attempt to prove the existence of anthropogenic global warming remove the obvious linear effects of El Niño - Southern Oscillation (ENSO) events and of stratospheric aerosols discharged by explosive volcanic erVOLCANIC AEROSOLS HELP TO SHOW THE TIMING OF THE WARMING Many papers and blog posts that attempt to prove the existence of anthropogenic global warming remove the obvious linear effects of El Niño - Southern Oscillation (ENSO) events and of stratospheric aerosols discharged by explosive volcanic erAEROSOLS HELP TO SHOW THE TIMING OF THE WARMING Many papers and blog posts that attempt to prove the existence of anthropogenic global warming remove the obvious linear effects of El Niño - Southern Oscillation (ENSO) events and of stratospheric aerosols discharged by explosive volcanic eraerosols discharged by explosive volcanic ervolcanic eruptions.

Stratospheric ozone in models is erroneously being driven CFC emissions rather than ozone destroying sulphuric acid aerosols for stratospheric volcanic eruptions, and thus also providing a spurious anthropogenic post-Stratospheric ozone in models is erroneously being driven CFC emissions rather than ozone destroying sulphuric acid aerosols for stratospheric volcanic eruptions, and thus also providing a spurious anthropogenic post-stratospheric volcanic eruptions, and thus also providing a spurious anthropogenic post-2000 forcing.

New VICS publication by Matthew Toohey and Michael Sigl on volcanic stratospheric sulfur injections and aerosol optical depth from 500 BCE to 1900 C https://www.earth-syst-sci-data.net/9/809/2017/essd-9-809-2017.html …

«We use 1280 years of control simulation, with constant preindustrial forcings including constant specified CO2, and a five - member ensemble of historical simulations from 1850 — 2005 including prescribed historical greenhouse gas concentrations, SO2 and other aerosol - precursor emissions, land use changes, solar irradiance changes, tropospheric and stratospheric ozone changes, and volcanic aerosol (ALL), following the recommended CMIP5 specifications.

[i] This is treating missing 1861 - 1879 values as the same as for 1880, except for stratospheric (volcanic) aerosols.

Add to that scaled monthly sunspot data to introduce the 0.1 deg C variations is surface temperature resulting from the solar cycle and add scaled monthly Stratospheric Aerosol Optical Depth data for dips and rebounds due to volcanic eruptions, and global surface temperature anomalies can be reproduced quite well.

«Here, it is sufficient to note that many of the 20CEN / A1B simulations neglect negative forcings arising from stratospheric ozone depletion, volcanic dust, and indirect aerosol effects on clouds... It is likely that omission of these negative forcings contributes to the positive bias in the model average TLT trends in Figure 6F.

Neely (2013 http://onlinelibrary.wiley.com/doi/10.1002/grl.50263/abstract): «Comparison of the model results to observations reveals that moderate volcanic eruptions, rather than anthropogenic influences, are the primary source of the observed increases in stratospheric aerosol.»

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».

Vernier, J. - P., L.W. Thomason, et al. 2011: Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade.

Volcanic aerosols will cool depending on the quantity and duration of their contribution to stratospheric aerosols, with Pinatubo (1991) associated with two to three years of cooling.

Interactive microphysics - chemistry - climate models (Rozanov et al., 2002, 2004; Shindell et al., 2003b; Timmreck et al., 2003; Dameris et al., 2005) indicate that aerosol - induced stratospheric heating affects the dispersion of the volcanic aerosol cloud, thus affecting the spatial RF.

Fourth, volcanic aerosols provide surfaces for heterogeneous chemistry affecting global stratospheric ozone distributions (Chipperfield et al., 2003) and perturbing other trace gases for a considerable period following an eruption.

Despite differences in volcanic aerosol parameters employed, models computing the aerosol radiative effects interactively yield tropical and global mean lower - stratospheric warmings that are fairly consistent with each other and with observations (Ramachandran et al., 2000; Hansen et al., 2002; Yang and Schlesinger, 2002; Stenchikov et al., 2004; Ramaswamy et al., 2006b); however, there is a considerable range in the responses in the polar stratosphere and troposphere.

This takes account of anthropogenic influences plus solar irradiance, volcanic stratospheric aerosols and ENSO.

The technique, which is known as «stratospheric aerosol injection», could cool the planet in a similar way to a large volcanic eruption.

Recent measurements demonstrate that the «background» stratospheric aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions.

But to quantify the influences (or «forcings» in climate jargon) even further, they considered three anthropogenic forcings — well - mixed greenhouse gases, sulfate aerosols, and tropospheric and stratospheric ozone — as well as two natural forcings — changes in solar irradiance and volcanic aerosols — all of which are likely to influence tropopause height.»

Forster et al. (2007) described four mechanisms by which volcanic forcing influences climate: RF due to aerosol — radiation interaction; differential (vertical or horizontal) heating, producing gradients and changes in circulation; interactions with other modes of circulation, such as El Niño - Southern Oscillation (ENSO); and ozone depletion with its effects on stratospheric heating, which depends on anthropogenic chlorine (stratospheric ozone would increase with a volcanic eruption under low - chlorine conditions).

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.

Notice that the effect there is the opposite of the effect of adding volcanic aerosols, which cool the global climate due to stratospheric effects.

Proposals for addressing global warming now include geo - engineering whereby tiny particles are injected into the stratosphere to emulate the cooling effects of stratospheric aerosol of a volcanic eruption (Levitt and Dubner 2009).