Sentences with phrase «aerosol forcing change»

Gregory 02 provides a good explanation for the basis of what I have done, although its observational data (and its model derived aerosol forcing change) has now been superceded.

The aerosol forcing change has been fairly flat over the last few decades according to the AR5 figure.

It allows aerosol forcing changes to be estimated from observations using the fact that aerosols are mostly in the NH.

Not exact matches

Taking factors such as sea surface temperature, greenhouse gases and natural aerosol particles into consideration, the researchers determined that changes in the concentration of black carbon could be the primary driving force behind the observed alterations to the hydrological cycle in the region.

Climate model projections neglecting these changes would continue to overestimate the radiative forcing and global warming in coming decades if these aerosols remain present at current values or increase.

Near - global satellite aerosol data imply a negative radiative forcing due to stratospheric aerosol changes over this period of about — 0.1 W / m2, reducing the recent global warming that would otherwise have occurred.

Professor Sybren said: «It can be excluded, however, that this hiatus period was solely caused by changes in atmospheric forcing, either due to volcanic eruptions, more aerosols emissions in Asia, or reduced greenhouse gas emissions.

Similarly (and perhaps relatedly), the magnitude of the change in aerosol forcing from ~ 1975 to present relative to the change in all forcings is much smaller than from pre-ind through present, which I think should make the TCR estimated over that period insensitive to the value of E.

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).

There are multiple anthropogenic forcings that have quite different impacts (e.g. anthropogenic greenhouse gas increases, aerosols, land - use changes and, yes, stratospheric ozone depletion).

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

Themes: Aerosols, Arctic and Antarctic climate, Atmospheric Science, Climate modelling, Climate sensitivity, Extreme events, Global warming, Greenhouse gases, Mitigation of Climate Change, Present - day observations, Oceans, Paleo - climate, Responses to common contrarian arguments, The Practice of Science, Solar forcing, Projections of future climate, Climate in the media, Meeting Reports, Miscellaneous.

My main problem with that study is that the weather models don't use any forcings at all — no changes in ozone, CO2, volcanos, aerosols, solar etc. — and so while some of the effects of the forcings might be captured (since the weather models assimilate satellite data etc.), there is no reason to think that they get all of the signal — particularly for near surface effects (tropospheric ozone for instance).

While a relatively minor part of the overall aerosol mass, changes in the anthropogenic portion of aerosols since 1750 have resulted in a globally averaged net radiative forcing of roughly -1.2 W / m2, in comparison to the overall average CO2 forcing of +1.66 W / m2.

The forcing over the last 150 years is around 1.6 W / m2 (including cooling effects from aerosols and land use change) but the climate is not (yet) in equilibirum, and so the full temperature response has not been acheived.

Forcing caused by changes in the Sun's brightness, by dust in the atmosphere, or by volcanic aerosols can also be translated into radiative fForcing caused by changes in the Sun's brightness, by dust in the atmosphere, or by volcanic aerosols can also be translated into radiative forcingforcing.

Forcing changes of similar magnitude, due to water vapour variations, are measurable as regional temperature changes in Europe, see Philipona, but aerosol changes are not...

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.

Steven J. Ghan • Contributing Author, Working Group I, «Aerosols, Their Direct and Indirect Effects,» IPCC Third Assessment Report (2001) • Contributing Author, Working Group I, «Radiative Forcing of Climate Change,» IPCC Third Assessment Report (2001).

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.

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.

This method tries to maximize using pure observations to find the temperature change and the forcing (you might need a model to constrain some of the forcings, but there's a lot of uncertainty about how the surface and atmospheric albedo changed during glacial times... a lot of studies only look at dust and not other aerosols, there is a lot of uncertainty about vegetation change, etc).

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.

Clearly, there are many positive forcings (warming influences) and negative forcings (cooling influences)-- the total includes methane, N2O, black carbon, small changes in sunlight, aerosols, etc..

The measured energy imbalance accounts for all natural and human - made climate forcings, including changes of atmospheric aerosols and Earth's surface albedo.

Specification now of a CO2 target more precise than < 350 ppm is difficult and unnecessary, because of uncertain future changes of forcings including other gases, aerosols and surface albedo.

Thus to provide the clearest picture of the CO2 effect, we approximate the net future change of human - made non-CO2 forcings as zero and we exclude future changes of natural climate forcings, such as solar irradiance and volcanic aerosols.

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.

One type of inverse method uses the ranges of climate change fingerprint scaling factors derived from detection and attribution analyses that attempt to separate the climate response to greenhouse gas forcing from the response to aerosol forcing and often from natural forcing as well (Gregory et al., 2002a; Stott et al., 2006c; see also Section 9.4.1.4).

Earth's measured energy imbalance has been used to infer the climate forcing by aerosols, with two independent analyses yielding a forcing in the past decade of about − 1.5 W / m2 [64], [72], including the direct aerosol forcing and indirect effects via induced cloud changes.

These provide the range of fingerprint magnitudes (e.g., for the combined temperature response to different aerosol forcings) that are consistent with observed climate change, and can therefore be used to infer the likely range of forcing that is consistent with the observed record.

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].

In addition, since the global surface temperature records are a measure that responds to albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition of various forcings into the oceans / atmosphere / land / cryosphere, teasing out just the effect of CO2 + water vapor over the short term is difficult to impossible.

More importantly, this system has the very nice property that the global mean of instantaneous forcing calculations (the difference in the radiation fluxes at the tropopause when you change greenhouse gases or aerosols or whatever) are a very good predictor for the eventual global mean response.

To better understand what Kilimanjaro and other tropical glaciers are telling us about climate change, one ultimately ought to drive a set of tropical glacier models with GCM simulations conducted with and without anthropogenic forcing (greenhouse gases and sulfate aerosol).

Of the forcings leading to a warming in the early part of the records, solar, decreasing volcanism and GHGs all play a part (and with a role for cooling due to land use change and aerosol increases).

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.

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

Now if this were the case, changes in the forcing due to reflective aerosols at roughly the beginning of World War II and shortly after the enforcement of the Clean Air Laws in the developed economies might very well explain a transition from one climate mode regime to another — that is, if the climate system is particularly sensitive to changes in forcings.

The most extreme scenario postulated in TAR (A1F1) already has a big reduction in sulphate aerosol forcing, and so the temperature changes by 2100 are almost purely a function of the GHG forcing.

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.

If you «use all of the data» you can't detect any change in trend from forcings known to make a difference (e.g. sulfate aerosols, which peaked in the 1940 - 1970 range from US sources and again later from Chinese).

While there is good data over the last century, there were many different changes to planet's radiation balance (greenhouse gases, aerosols, solar forcing, volcanoes, land use changes etc.), some of which are difficult to quantify (for instance the indirect aerosol effects) and whose history is not well known.

I have no doubts about the fact that climate change is happening and that the warming trend is real and unusual, given the GHG / aerosol forcings.

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.

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.

So the climate sensitivity is itself very sensitive to changes in the negative forcing from aerosols.

Except that GHG forcing + cooling aerosol forcing results in less precipitation globally in general than reduced GHG forcing that produces the same global average temperature, as found in «Climate Change Methadone» elsewhere at RC.

For instance, simulations were run that only used the changes in volcanic forcing, or in land use or in tropospheric aerosols.

You need information about the degree of intrinsic variability, estimates of the natural forcings (principally solar and volcanic), and estimates of the human related forcings (GHGs, land use change, aerosols etc.).