Sentences with phrase «water vapor feedback which»

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.

In an essay in BioScience magazine, the Wildlife Conservation Society's Douglas Sheil and co-authors discuss the «biotic pump» hypothesis of Russian researchers Anatassia Makarieva and Victor Gorshov, which contends that rainforests attract water vapor, leading to rain, lower local atmospheric pressure and a feedback loop that keeps the whole system going.

This clearly confuses relative humidity in the boundary layer (which determines evaporation) and specific humidity throughout the troposphere (which determines the strength of the water vapor feedback).

From the paper...» These results provide enhanced confidence in the range of climate sensitivity in climate simulations, which are based on a positive uppertropospheric water vapor feedback.

[Response: The concept of water vapor feedback (which goes back to Arrhenius, and was fully consolidated in the 1960's by Manabe and co-workers) has always stated that the water vapor was determined by temperature.

[1] CO2 absorbs IR, is the main GHG, human emissions are increasing its concentration in the atmosphere, raising temperatures globally; the second GHG, water vapor, exists in equilibrium with water / ice, would precipitate out if not for the CO2, so acts as a feedback; since the oceans cover so much of the planet, water is a large positive feedback; melting snow and ice as the atmosphere warms decreases albedo, another positive feedback, biased toward the poles, which gives larger polar warming than the global average; decreasing the temperature gradient from the equator to the poles is reducing the driving forces for the jetstream; the jetstream's meanders are increasing in amplitude and slowing, just like the lower Missippi River where its driving gradient decreases; the larger slower meanders increase the amplitude and duration of blocking highs, increasing drought and extreme temperatures — and 30,000 + Europeans and 5,000 plus Russians die, and the US corn crop, Russian wheat crop, and Aussie wildland fire protection fails — or extreme rainfall floods the US, France, Pakistan, Thailand (driving up prices for disk drives — hows that for unexpected adverse impacts from AGW?)

«It is now widely known that the water vapor feedback in general circulation models (GCMs) is close to that which would result from a climate ‐ invariant distribution of relative humidity [Soden and Held, 2006], as long anticipated before the advent of such models [e.g., Arrhenius, 1896; Manabe and Wetherald, 1967].»

Alternatively, more direct observations of that radiative imbalance would be nice, or better theoretical and observational understanding of the water vapor and cloud feedbacks, or more paleoclimate data which can give us constraints on historical feedbacks, but my guess is that ocean heat content measurements would be the best near term bet for improving our understanding of this issue.

These results provide quantitative evidence of the reliability of water vapor feedback in current climate models, which is crucial to their use for global warming projections.

Finally, because of the posited strong water vapor feedback, which depends on absolute, not anomaly, temperatures, one would expect that the relationship should be positive, not negative due to the greater rate of accumulation of water vapor at higher absolute temperatures.

But then there's feedbacks within the stratosphere (water vapor), which would increase the stratospheric heating by upward radiation from below, as well as add some feedback to the downward flux at TRPP that the upward flux at TRPP would have to respond to via warming below TRPP.

Re: # 139, ««The only feedback which is NOT significantly balanced is the water vapor cycle, but, again on a global scale that is just driven by the Clausius Clapyron relationship.

Simple physics dictates that with less sea ice there is magnified warming of the Arctic due to powerful albedo feedback; this in turn reduces the equator to pole temperature gradient which slows the jet stream winds causing them to become more meridional; this combined with 4 % more water vapor in the atmosphere (compared to 3 decades ago) is leading to much more extremes in weather.

The only feedback which is NOT significantly balanced is the water vapor cycle, but, again on a global scale that is just driven by the Clausius Clapyron relationship.

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).

If a doubling of CO2 resulted in a temperature increase of approximately 1 K before any non-Planck feedbacks (before water vapor, etc.), then assuming the same climate sensitivity to the total GHE, removing the whole GHE would result in about a (setting the TOA / tropopause distinction aside, as it is relatively small relative to the 155 W / m2 value) 155/3.7 * 1 K ~ = 42 K. Which is a bit more than 32 or 33 K, though I'm not surprised by the difference.

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).

The first is the paper «Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe» by Rolf Philipona et al. (GRL, 2005, subscription required for full text), which has attracted a certain amount of media attention.

Lindzen also suggested that water vapor would act as a negative feedback on global warming because the upper troposphere would dry out as it warmed (which also fits the «sky will open up» ideas) but the fact is that the troposphere has gotten wetter.

The second nonlinearity is that the water vapor feedback depends on the moisture content of the air, which via the Clausius - Clapeyron relation is a nonlinear function of temperature.

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.

goodsprk: It relies on not simply CO2, but on feedback from increased CO2 raising the temperature which increases the water vapor in the atmosphere which the alarmist assume will actually breaking up the low level clouds and forming high level cirrus clouds that will trap more heat.

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.

It relies on not simply CO2, but on feedback from increased CO2 raising the temperature which increases the water vapor in the atmosphere which the alarmist assume will actually breaking up the low level clouds and forming high level cirrus clouds that will trap more heat.

«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.

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.

There is much discussion as to the value of the climate sensitivity, which swirls around whether there is net positive or negative feedback from things like clouds and water vapor.

For a degree of warming, CO2 adds 10 - 15 ppm which may add another couple of tenths of a degree including its own water vapor feedback.

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.

Dan Pangborn: The still - rising water vapor (WV) is rising at 1.5 % per decade which is more than twice as fast as expected from water temperature increase alone (feedback, engineering definition).

The POSITIVE feedback between CO2 and WATER VAPOR which is suppose to result in a lower tropospheric hotspot has not materialized.

But what happened to the «feedbacks» from water vapor, clouds, etc., which (according to IPCC AR4) increase the 2xCO2 ECS to 3.2 C and the transient temperature response to ~ 2C?

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

Quoting Dr Roy Spencer: «One of the most robust feedback relationships across the IPCC climate models is that those models with the strongest positive water vapor feedback have the strongest negative lapse rate feedback (which is what the «hot spot» would represent).

The 0.9 degr.C for 2xCO2 is from the Modtran program, carefully composed from laboratory measurements, where line by line absorption characteristics were measured and implemented for different air pressures (heights), water, CO2 and CH4 levels, for different parts of the globe and with or without clouds, rain,... That is a basic «model», without any real life feedbacks (except water vapor, which may be included in different ways).

(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.

ris — The reduced IR cooling results from increased water vapor which is increasing more than twice as fast as expected from temperature increase alone (increased vapor pressure, hence increased water vapor, from increased temperature is what causes the feedback).

AGW climate scientists seem to ignore that while the earth's surface may be warming, our atmosphere above 10,000 ft. above MSL is a refrigerator that can take water vapor scavenged from the vast oceans on earth (which are also a formidable heat sink), lift it to cold zones in the atmosphere by convective physical processes, chill it (removing vast amounts of heat from the atmosphere) or freeze it, (removing even more vast amounts of heat from the atmosphere) drop it on land and oceans as rain, sleet or snow, moisturizing and cooling the soil, cooling the oceans and building polar ice caps and even more importantly, increasing the albedo of the earth, with a critical negative feedback determining how much of the sun's energy is reflected back into space, changing the moment of inertia of the earth by removing water mass from equatorial latitudes and transporting this water vapor mass to the poles, reducing the earth's spin axis moment of inertia and speeding up its spin rate, etc..

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.

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.

On the other hand the projected positive feedbacks you support, which are COMPLETELY theoretical, depend on the LEAST understood aspects of the affect of water vapor and cloud formation, so the strong feedbacks PROJECTED are the least dependable, while the «OBSERVATIONS» used by Lindzen, Spencer, and others, support the lower estimates of climate sensitivity.

But I am not about to buy in on the AGW premise of IPCC, which is based on a mean ECS value of 3.2 C (with a «fat tail»), which is in turn based on net positive feedback from clouds and a water vapor feedback based on essentially maintaining constant relative humidity with warming, all of which is solely based on model predictions and not on empirical evidence.

Dessler himself is a big warmist and expresses his bias this way: «Everything shows that the climate models are probably getting the water vapor feedback right, which means that unless we reduce emissions, it is going to get much, much warmer on our planet by the end of the century.,» That was in 2009.

IOW we have both the magnitude and the sign of water vapor feedback still in question (except, of course, by the IPCC orthodoxy, which assumes positive feedback at a rate high enough to essentially maintain constant relative humidity in lockstep with Clausius - Clapeyron).