Sentences with phrase «vapor feedback effect»

Even though we have known and understood for decades the basic science of the terrestrial greenhouse effect, and water vapor feedback effects, in the current climate (politically speaking) of the frequently expressed irrational thinking, there is unfortunately a clear and pressing need to keep on repeating and explaining the most basic of global climate concepts.

Not exact matches

Increase the global temperature a bit, however, and there could be a bad feedback effect, with water evaporating faster, freeing water vapor (a potent greenhouse gas), which traps more heat, which drives carbon dioxide from the rocks, which drives temperatures still higher.

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.

While the ECS factors in such «fast» feedback effects as changes in water vapor — water itself is a greenhouse gas, and saturates warm air better than cold — they argued that slow feedbacks, such as changes in ice sheets and vegetation, should also be considered.

I guess I am surprised that with better understanding of the importance of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in albedo, effects of the deposition of soot and dust on snow and ice decreasing albedo, and a recognition of the importance of GHGs that were probably not considered 30 years ago, that the sensitivity has changed so little over time.

When the CLIMAP data proved to be wrong, and was replaced by more reliable estimates showing a substantial tropical surface temperature drop, Lindzen had to abandon his then - current model and move on to other forms of mischief (first the «cumulus drying» negative water vapor feedback mechanism, since abandoned, and now the «Iris» effect cloud feedback mechanism).

For starters, one simply can not equate the positive feedback effect of melting ice (both reduced albedo and increased water vapor) from that of leaving maximum ice to that of minimum ice where the climate is now (and is during every interglacial period).

However, this climate sensitivity includes only the effects of fast feedbacks of the climate system, such as water vapor, clouds, aerosols, and sea ice.

I guess I am surprised that with better understanding of the importance of water vapor feedback, sulfate aerosols, black carbon aerosols, more rapid than expected declines in sea ice and attendant decreases in albedo, effects of the deposition of soot and dust on snow and ice decreasing albedo, and a recognition of the importance of GHGs that were probably not considered 30 years ago, that the sensitivity has changed so little over time.

«By comparing the response of clouds and water vapor to ENSO forcing in nature with that in AMIP simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor feedbacks has revealed two common biases in the models: (1) an underestimate of the strength of the negative cloud albedo feedback and (2) an overestimate of the positive feedback from the greenhouse effect of water vapor.

This sensitivity estimate is not the last word on the subject, because of uncertainties in the approximate formulae used to compute the terms in the energy balance, and neglect of possible effects of water vapor feedback on the surface budget.

Data from satellite observations «suggest that greenhouse models ignore negative feedback produced by clouds and by water vapor, that diminish the warming effects» of human carbon dioxide emissions.

Warming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from stratospheric water vapor; stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than stratospheric water vapor)(in the limit of an optically thin stratosphere at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by stratospheric warming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux at TOA).

Arbiters of Energy discussions of the Iris effect and water - vapor feedbacks

Re 9 wili — I know of a paper suggesting, as I recall, that enhanced «backradiation» (downward radiation reaching the surface emitted by the air / clouds) contributed more to Arctic amplification specifically in the cold part of the year (just to be clear, backradiation should generally increase with any warming (aside from greenhouse feedbacks) and more so with a warming due to an increase in the greenhouse effect (including feedbacks like water vapor and, if positive, clouds, though regional changes in water vapor and clouds can go against the global trend); otherwise it was always my understanding that the albedo feedback was key (while sea ice decreases so far have been more a summer phenomenon (when it would be warmer to begin with), the heat capacity of the sea prevents much temperature response, but there is a greater build up of heat from the albedo feedback, and this is released in the cold part of the year when ice forms later or would have formed or would have been thicker; the seasonal effect of reduced winter snow cover decreasing at those latitudes which still recieve sunlight in the winter would not be so delayed).

If C02 is the largest single contributing factor to the Greenhouse Effect (because supposedly water vapor is only involved as a feedback to primary chemistry involving C02 itself), and C02 lags temperature increases (as has been stated on this very blog), how has the Earth ever returned to colder glacial conditions following periods of warming?

When the CLIMAP data proved to be wrong, and was replaced by more reliable estimates showing a substantial tropical surface temperature drop, Lindzen had to abandon his then - current model and move on to other forms of mischief (first the «cumulus drying» negative water vapor feedback mechanism, since abandoned, and now the «Iris» effect cloud feedback mechanism).

There will be Regionally / locally and temporal variations; increased temperature and backradiation tend to reduce the diurnal temperature cycle on land, though regional variations in cloud feedbacks and water vapor could cause some regions to have the opposite effect; changes in surface moisture and humidity also changes the amount of convective cooling that can occur for the same temperature distribution.

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).

Is less poleward transport of heat by the Gulf Stream as the AMOC weakens a positive feedback for global warming, since that energy will escape more slowly in the humid (higher water vapor GHG effect) tropics than near the poles?

A Lacis: You don't seem to appreciate the fact that water vapor and clouds are feedback effects, which means that the water vapor and cloud distributions depend directly on the local meteorological conditions, and are therefore constrained by the temperature dependence of the Clausius - Clapeyron relation.

You don't seem to appreciate the fact that water vapor and clouds are feedback effects, which means that the water vapor and cloud distributions depend directly on the local meteorological conditions, and are therefore constrained by the temperature dependence of the Clausius - Clapeyron relation.

Water vapor feedback can also amplify the warming effect of other greenhouse gases, such that the warming brought about by increased carbon dioxide allows more water vapor to enter the atmosphere.

«You don't seem to appreciate the fact that water vapor and clouds are feedback effects, which means that the water vapor and cloud distributions depend directly on the local meteorological conditions»

Disputes within climate science concern the nature and magnitude of feedback processes involving clouds and water vapor, uncertainties about the rate at which the oceans take up heat and carbon dioxide, the effects of air pollution, and the nature and importance of climate change effects such as rising sea level, increasing acidity of the ocean, and the incidence of weather hazards such as floods, droughts, storms, and heat waves.

The notion of an H2O positive feedback (which probably is present on a clear day) is squashed by this process.While warmer air can hold exponentially more water vapor, presumably increasing greenhouse effects (an process the IPCC hangs its collective hat on), it is also this exact same property that vastly improves the chances of convective and phase change heat transport by thunderstorms.

If, for instance, CO2 concentrations are doubled, then the absorption would increase by 4 W / m2, but once the water vapor and clouds react, the absorption increases by almost 20 W / m2 — demonstrating that (in the GISS climate model, at least) the «feedbacks» are amplifying the effects of the initial radiative forcing from CO2 alone.

Cloud variations are obviously an important element on a global scale, but the effects of Arctic ice melting are important locally and also a non-trivial fraction of global albedo feedbacks, which are a contributor to total feedback that is smaller than those from water vapor and probably from cloud feedbacks, but not insignificant.

A substantial reduction in water vapor (shown below, from Lacis et al (2010) as well as increase in the surface albedo are important feedbacks here, showing that removing the non-condensing greenhouse gases (mostly CO2) in the atmosphere can collapse nearly the entire terrestrial greenhouse effect.

Its warming effect, however, is simultaneously amplified and dampened by positive and negative feedbacks such as increased water vapor (the most powerful greenhouse gas), reduced albedo, which is a measure of Earth's reflectivity, changes in cloud characteristics, and CO2 exchanges with the ocean and terrestrial ecosystems.

He assumes a feedback of 1.6 for water vapor, 1.3 for clouds, and 1.1 for ice / albedo effects.

''... the warming is only missing if one believes computer models where so - called feedbacks involving water vapor and clouds greatly amplify the small effect of CO2.»

One important feedback, which is thought to approximately double the direct heating effect of carbon dioxide, involves water vapor, clouds and temperature.

Results of previously published empirical studies are used to demonstrate that the water vapor feedback mechanism, so important to the calculation of a significant climatic effect for a doubling of the atmospheric CO2 concentration, appears to be counter-balanced by another feedback mechanism of opposite sign.

We have wide upper and lower enhancement bounds on this partial derivative based on water vapor and cloud effects, including the possibility of negative feedbacks.

(While the data did suggest strong positive water vapor feedback, which enhances warming, that was far exceeded by the cooling effect of negative feedback from cloud changes.)»

I am very skeptical of the indirect feedback amplification effects put down to CO2 (and water vapor), which supposedly double or triple the direct effects, don't see any observation evidence for this and the last 7 years have only firmed my skepticism.

At 0.04 % of the atmosphere the effect couldn't be very great, and yet somehow water vapor became a «feedback» that would multiply the effect.

The physics is very clear that CO2 is the principal greenhouse forcing gas, and that atmospheric water vapor acts as a feedback magnifier that enhances the terrestrial greenhouse effect.

Andrew Lacis wrote: (3) Water vapor and clouds account for about 75 % the strength of the terrestrial greenhouse effect, but are feedback effects that require sustained radiative forcing to maintain their atmospheric distribution.

Non-condensing greenhouse gases, which account for 25 % of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75 % of the greenhouse effect.

It only becomes significant in the models by assuming that water vapor concentration increases in response to the slight warming produced by CO2 increases and therefore constitutes a powerful positive feedback effect which triples the effect of CO2 by itself.

A. Lacis writes «The physics is very clear that CO2 is the principal greenhouse forcing gas, and that atmospheric water vapor acts as a feedback magnifier that enhances the terrestrial greenhouse effect.

Phrases such as «outright destructive dishonesty» have been directed toward lots of things, including the benign statement that the CO2 effect might be overestimated, or the the water vapor feedback is improperly assumed to be positive..

Noncondensing greenhouse gases, which account for 25 % of the total terrestrial greenhouse effect, thus serve to provide the stable temperaturestructure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75 % of the greenhouse effect.

Instead, the aim of our Science paper was to illustrate as clearly and as simply as possible the basic operating principles of the terrestrial greenhouse effect in terms of the sustaining radiative forcing that is provided by the non-condensing greenhouse gases, which is further augmented by the feedback response of water vapor and clouds.

Noncondensing greenhouse gases, which account for 25 % of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75 % of the greenhouse effect.

(3) Water vapor and clouds account for about 75 % the strength of the terrestrial greenhouse effect, but are feedback effects that require sustained radiative forcing to maintain their atmospheric distribution.

«Stratospheric water vapor has a positive climate feedback effect: a warming climate increases stratospheric water vapor, and the increased stratospheric water vapor enhances surface warming.

If there was no greenhouse effect or if something were to block it any doubling of carbon dioxide would yield zero degrees warming and the water vapor feedback likewise would be zero, giving a climate sensitivity of exactly zero for this doubling.