Sentences with phrase «volcanic aerosols there»

Thus the changes in the stratosphere are basically a function of the greenhouse gases, ozone levels and volcanic aerosols there.

Not exact matches

To the contrary, as there is an inverse correlation between low cloud cover and solar irradiation, and solar / volcanic have influences in the stratosphere, non-excisting for CO2 or human made aerosols.

There are other climate influences beside CO2, notably anthropogenic and volcanic aerosols, as well as some solar fluctuation.

Here a reaction on the main points about the natural (solar, volcanic) vs. man - made (GHGs, aerosols) sensitivity: — If there was a larger temperature variation in the past millennium, the mathematical evidence is that an increase of one of the terms of the temperature trend equation must go at the cost of one or more other terms of the equation.

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.

Does this not show that the models that incorporate volcanic forcing can not model aerosol forcing since there are no measurements to use to parameterize and per Hansen, we do not know enough to use first principles.

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.

Here a reaction on the main points about the natural (solar, volcanic) vs. man - made (GHGs, aerosols) sensitivity: — If there was a larger temperature variation in the past millennium, the mathematical evidence is that an increase of one of the terms of the temperature trend equation must go at the cost of one or more other terms of the equation.

Positing that there have been any times with zero volcanic aerosols is almost as ludicrous as positing there is no water vapor feedback; neither compares with trying to use them as the basis for a long winded attempt at justification for a wished for «safe» climate sensitivity.

Given the total irrelevance of volcanic aerosols during the period in question, the only very modest effect of fossil fuel emissions and the many inconsistencies governing the data pertaining to solar irradiance, it seems clear that climate science has no meaningful explanation for the considerable warming trend we see in the earlier part of the 20th century — and if that's the case, then there is no reason to assume that the warming we see in the latter part of that century could not also be due to either some as yet unknown natural force, or perhaps simply random drift.

«On the other hand, we might assume that there has been some lower, but non-zero «background level» of volcanic aerosols - let's arbitrarily make it 2 on a scale of 10, for ease of discussion.

The decay times of volcanic aerosols are approximately exponential, though there are seasonal and geographic influences *; Observations vary from ~ 5 to 95 months for 1 / e; eruption durations vary from week to decades; the mean time between VEI 4 eruptions is 18 months.

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).

«How, pray tell, would volcanic aerosols «dissipate» if there were no lack of volcanic activity continually replenishing them?»

And yes, if there were no lack of additional volcanic aerosols then the rebound would be delayed.

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.

If so, there would appear to me to be little value in comparing the two when looking for aerosol sensitivity to volcanic eruptions.

There are multilple causes cited in the post above volcanics, aerosols, solar (which by the way the recent minima was only unusual by its longevity not its amplitude) but we can leave Hansen 2011 to rebute your point 1

If the cooling from 1940 to 1975 was due (mainly) to aerosols, I would expect then that we would still be experiencing cooling, roughly equal to the 1960s, but certainly not warming faster than the pre-1940 era (when there was less volcanic activity, more active sun etc).

These scenarios presume that there are no major volcanic eruptions and that anthropogenic aerosol emissions are rapidly reduced during the near term.

However, there is not compelling evidence that anthropogenic CO2 was sufficient to influence Earth's temperatures prior to 1950, i.e. «Climate model simulations that consider only natural solar variability and volcanic aerosols since 1750 — omitting observed increases in greenhouse gases — are able to fit the observations of global temperatures only up until about 1950.»

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».

I consider it as very likely that the 20 year trends will still be statistically significant also in three, five or ten years from now, unless there is some strong volcanic explosion that blows a lot of reflecting aerosols in the stratosphere causing a temporary temperature dip, or some other cause the effect of which is explainable within the framework of current knowledge about the climate system, but as event not really predictable.

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.

There are a lot of questions: what is the climate response to solar activity and no solar activity, changes in TSI, spectral variability, particle events, cosmic - ray variability, volcanic aerosols, the Antarctic ozone hole.

As for aerosols, the volcanic record is what it is, after Katmai there are no major eruptions, so that simplifies the aerosol record somewhat.

We have poor direct information on aerosols, but the fossil fuel consumption rate is low, and there is only one major volcanic episode, so we can assume aerosol cooling is not significant.

This increase is not instantaneous as there are many other drivers likes aerosols, sun, volcanic eruptions and also the natural variability of the climatic system.

It is easy but somewhat speculative to invoke combinations of solar changes, aerosols (anthropogenic and volcanic), and internal climate modes to explain the deviations from a smoothly rising curve, and there are ample data to indicate these played a role.

There has been no significant volcanoes since 1992 that could have affected temperatures as shown in this graph of volcanic aerosols.

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.

Aerosols from such episodic volcanic events exert a transitory negative RF; however, there is limited knowledge of the RF associated with eruptions prior to Mt. Pinatubo.

This can be done to the ENSO signal (there are at least six different ENSO indices, however, and so you have to choose one that you think is «best» — there's a paper I'm going to track down that supposedly indicated that the simple indices are just as good as the complex, multivariate indices, but I haven't done so yet) and the volcanic aerosol signal.

However, there is low confidence in quantifying the role of forcing trend in causing the hiatus because of uncertainty in the magnitude of the volcanic forcing trends and low confidence in the aerosol forcing trend.

The Sulfate cooling mechanism is also evidenced whenever there is a high ejecta mass volcanic eruption, which causes a measurable cooling effect, for about 3 years after an eruption; until the sulfate particulate aerosols diminish in the atmosphere to the point that they become negligible.

But then there was a volcanic eruption, and she reversed her prediction claiming that the volcanic aerosols would soak up the moisture in the air or some such thing.

Third: There was no cooling in the 1920s; in fact that was the start of a multidecadal warming trend that lasted until just after World War II (followed by a brief cooling trend, possibly due to increased aerosols dimming incoming sunlight together with some pretty big volcanic eruptions which did the same thing).

There have been numerous research papers and reviews published over the past 10 years, including several in prestigious journals such as Nature and Science, that conclude that the observed temperature changes over the past 100 years are consistent with the combined changes in atmospheric aerosols (volcanic and anthropogenic), land surface changes, variations in solar irradiance and increases in greenhouse gases.

On volcanic forcing: I am unsure how well volcanic aerosols distribute across the stratosphere, and whether there's an imbalance between SH and NH there.

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

There are perhaps good reasons for this like IPCC treatment of aerosols and a subsequent volcanic eruption (but forecast failures always tell us why they were wrong, which is part of their value).