Sentences with phrase «albedo feedbacks have»

New techniques that evaluate surface albedo feedbacks have recently been developed.

The SW surface albedo feedback has a value of +0.3 ± 0.1 W m − 2 K − 1 (43, 45).

Studies of the cryospheric albedo feedback have a long history.

2) The ESS value obtained would (ignoring the more complex first point) perhaps be applicable to a glacial - interglacial transition, but decidedly not to an interglacial - «hyperinterglacial» transition, where the ice - albedo feedback would of course be much smaller because of the much smaller ice - covered surface area.

Not exact matches

Recently, however, ice - ocean «albedo feedback» has emerged as a key cause for sea ice melt.

This positive feedback phenomenon, called the runaway albedo effect, would eventually lead to a single dominating ice cap, like the one observed on Pluto.

«If you can time your emissions so they have the least impact then you will not trigger these very sensitive regions to start warming by this ice albedo feedback process.»

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.

Anyone who accepts that sunlight falling on ice free waters which has less reflectivity than sunlight falling on a large ice mass covering those waters and also accepts that this reduction in albedo has a positive feedback effect, leading to further warming, can't help but opt for A or B, it seems to me.

There are many other feedbacks, most notably the the ice - albedo effect of Arctic sea ice, which have already passed their tipping points.

Most sources claim that it would inrease albedo and lead to a positive feedback.

i.e. water vapour would have to go down as temperature rises, low clouds would have to be incredibly sensitive, high clouds not sensitive at all — and forget the ice - albedo feedback!

There was more ice around in the LGM and that changes the weighting of ice - albedo feedback, but also the operation of the cloud feedback since clouds over ice have different effects than clouds over water.

I imagine the CO2 feedback would be more important as a feedback to any albedo changes brought by warming.

There are many other feedbacks, most notably the the ice - albedo effect of Arctic sea ice, which have already passed their tipping points.

I would like to see a discussion of the likelihood that factors traditionally viewed as slow response feedback factors (such as Arctic albedo, or high methane emissions permafrost degradation) may actually become faster response feedback factors.

[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?)

As I understand it the issue of whether the feedback of clouds is positive or negative has nothing whatsoever to do with the contribution clouds make to the earth's albedo.

You are welcome to try something similar with global radiative forcing fluctuation, but if you do it will be rather tricky to isolate the cloud effect, since you have the snow and ice albedo effect to deal with then, which are largely temperature - related feedbacks.

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.

On the possibility of a changing cloud cover «forcing» global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.

Simon said:» As I understand it the issue of whether the feedback of clouds is positive or negative has nothing whatsoever to do with the contribution clouds make to the earth's albedo.»

Gavin disputes that the main driver of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification of global warming but positive feedback, which would not be explained simply by radiative forces and ocean currents.

involves runaway ice albedo feedback — it stops (starts) when the «iceline» is at the equator; it starts (stops) when the «ice line» reaches some latitude when the sensitivity goes to infinity (or when all the ice has been eliminated).

For instance, increasing cloud cover due to global warming may change the albedo, but this would be a feedback to a larger warming effect, rather than a cooling.

re 454 wili — of course, introducing additional feedbacks like vegetation albedo (boreal forests replacing tundra) and methane hydrate / clathrate, etc, could concievably make it runaway — again, limited by C reservoir and land area / latitude ranges (and some places would probably see a surface albedo increase).

For instance, the effect of soot making snow and sea ice darker has a higher efficacy than an equivalent change in CO2 with the same forcing, mainly because there is a more important ice - albedo feedback in the soot case.

(Orbital forcing doesn't have much of a global annual average forcing, and it's even concievable that the sensitivity to orbital forcing as measured in terms of global averages and the long - term response (temporal scale of ice sheet response) might be approaching infinity or even be negative (if more sunlight is directed onto an ice sheet, the global average albedo might increase, but the ice sheet would be more likely to decay, with a global average albedo feedback that causes warming).

«If you can time your emissions so they have the least impact then you will not trigger these very sensitive regions to start warming by this ice albedo feedback process.»

I have a question for the ice scientists: If an ice free Arctic summer becomes routine, say in 2013, how much will the absorption feedback vs. normal albedo raise global temperature?

I have a question about the potential albedo feedback effect on a ablating ice sheet surface.

Gavin has already pointed out that ceteris probably ain't paribus, as there could be negative feedbacks due to clouds that diminish the positive albedo feedbacks.

What would then be left would be primarily the positive feedbacks due to the carbon cycle, the cryosphere «albedo» feedback, and the effects of aerosols, but the last of these is quickly becoming amenable to calculation.

I would guess summer warming would melt polar ice, leading to ice albedo feedback and global warming.

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 we lose them rapidly then there would be a small rapid sea - level rise, major rapid local effects to do with huge quantities of meltwater, and an albedo feedback effect.

A really really last try: Let's stop reinventing the wheel (after all, the ice - albedo feedback discussion has a long history).

All of these have albedo effects and all are «slow» feedbacks which are considerably more sensitive than we expected — given a variety of feedbacks which we hadn't even been aware of before.

David has higlighted the fact that there are other, larger sources of methane, and of course we know that there are other albedo and carbon cycle feedbacks etc..

Most sources claim that it would inrease albedo and lead to a positive feedback.

It is not that the polar regions are amplifying the warming «going on» at lower latitudes, it is that any warming going on AT THE POLES is amplified through inherent positive feedback processes AT THE POLES, and specifically this is primarily the ice - albedo positive feedback process whereby more open water leads to more warming leads to more open water, etc. *** «Climate model simulations have shown that ice albedo feedbacks associated with variations in snow and sea - ice coverage are a key factor in positive feedback mechanisms which amplify climate change at high northern latitudes...»

«Climate model simulations have shown that ice albedo feedbacks associated with variations in snow and sea - ice coverage are a key factor in positive feedback mechanisms which amplify climate change at high northern latitudes...»

The water vapor, lapse - rate and ice - albedo feedbacks in isolation enhance the global warming that would result from increasing CO2 concentrations alone to around +2.2 °C.

A number of processes, other than surface albedo feedback, have been shown to also contribute to the polar amplification of warming in models (Alexeev, 2003, 2005; Holland and Bitz, 2003; Vavrus, 2004; Cai, 2005; Winton, 2006b).

The Arctic has been warming at twice the rate of the rest of the world for decades because of feedback loops that have reduced the albedo effect, a measure of the way Earth reflects heat.

In addition to direct MYI melt due to high - latitude warming, the impact of enhanced upper - ocean solar heating through numerous leads in decaying Arctic ice cover and consequent ice bottom melting has resulted in an accelerated rate of sea - ice retreat via a positive ice - albedo feedback mechanism.

The ice - albedo feedback is a very strong positive feedback that has been included in climate models since the 1970s.

It's positive albedo feedbacks according to him, of course, but you're not having any part of that, right?

As soon as the sun is bright enough, the ice would start to melt and an albedo feedback could make it melt very fast.