Sentences with phrase «snow albedo feedback»

The ice / snow albedo feedback is pretty small globally, but very important regionally.

Hall and Qu (2006) show that biases of a number of MMD models in reproducing the observed seasonal cycle of land snow cover (especially the spring melt) are tightly related to the large variations in snow albedo feedback strength simulated by the same models in climate change scenarios.

However, possible use of seasonal snow albedo feedback to evaluate snow albedo feedback under climate change conditions is of course dependent upon the realism of the correlation between the two feedbacks suggested by GCMs (Figure 8.16).

There are good reasons to assume that important amplifying feedbacks, such as the snow albedo feedback, become much weaker in warmer climates, which would result in an underestimation of climate sensitivity to CO2 doubling in such a regression.

Hall, A. & Qu, X. Using the current seasonal cycle to constrain the snow albedo feedback in future climate change.

Based on the understanding of both the physical processes that control key climate feedbacks (see Section 8.6.3), and also the origin of inter-model differences in the simulation of feedbacks (see Section 8.6.2), the following climate characteristics appear to be particularly important: (i) for the water vapour and lapse rate feedbacks, the response of upper - tropospheric RH and lapse rate to interannual or decadal changes in climate; (ii) for cloud feedbacks, the response of boundary - layer clouds and anvil clouds to a change in surface or atmospheric conditions and the change in cloud radiative properties associated with a change in extratropical synoptic weather systems; (iii) for snow albedo feedbacks, the relationship between surface air temperature and snow melt over northern land areas during spring and (iv) for sea ice feedbacks, the simulation of sea ice thickness.

Not exact matches

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.

Due to the positive feedback caused by the high albedo of snow and ice, susceptibility to falling into snowball states might be a generic feature of water - rich planets with the capacity to host life.

He then uses what information is available to quantify (in Watts per square meter) what radiative terms drive that temperature change (for the LGM this is primarily increased surface albedo from more ice / snow cover, and also changes in greenhouse gases... the former is treated as a forcing, not a feedback; also, the orbital variations which technically drive the process are rather small in the global mean).

Model performance in reproducing the observed seasonal cycle of land snow cover may provide an indirect evaluation of the simulated snow - albedo feedback under climate change.

This chemical weathering process is too slow to damp out shorter - term fluctuations, and there are some complexities — glaciation can enhance the mechanical erosion that provides surface area for chemical weathering (some of which may be realized after a time delay — ie when the subsequent warming occurs — dramatically snow in a Snowball Earth scenario, where the frigid conditions essentially shut down all chemical weathering, allowing CO2 to build up to the point where it thaws the equatorial region, at which point runaway albedo feedback drives the Earth into a carbonic acid sauna, which ends via rapid carbonate rock formation), while lower sea level may increase the oxidation of organic C in sediments but also provide more land surface for erosion... etc..

That is clearly the Milankovitch cycles that initiate the process — and CO2 and water vapor (along with changes in albedo due to snow and vegetation) are both feedbacks.

[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?)

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.

This positive climate feedback is greater than expected from the additional forcing alone, due to amplification by reduced surface albedo through melting of continental snow and decreased sea - ice coverage, especially in the wintertime.

In the NH a lot of land surrounding the arctic ocean is subject to the combination of decrease in seasonal snow cover (with climate warming), and decreasing albedo due to vegetation feedbacks.

, (3) changes in surface albedo of snow & ice due to changes in temperature and deposition of mineral and black carbon particulates, and last, but arguably most significantly (4) the intensity of the positive feedback that comes from the inevitable -LRB-?)

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.

Analysis of observed declines in sea ice and snow coverage from 1979 to 2008 suggests that the NH albedo feedback is between 0.3 and 1.1 W m — 2 °C — 1 (Flanner et al., 2011).

Furthermore, decline in snow cover and sea ice will tend to amplify regional warming through snow and ice - albedo feedback effects (see Glossary and Chapter 9).

(In the full 4 - dimensional climate, responses can also tend spread horizontally by convection (advection) and temporally by heat capacity, though «fingerprints» of horizontal and temporal variations in RF (externally imposed and feedback — snow and ice albedo, for example) can remain — this spreading is somewhat different as it relies in part on the circulation already present as well as circulation changes)

The details of the physics of different forcings (i.e. ozone effects due to solar, snow albedo and cloud effects due to aerosols etc.) do vary the feedbacks slightly differently though.

Both are related to feedback mechanisms which can amplify or dampen initial changes, such as the connection between temperature and the albedo associated with sea - ice and snow.

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).

Then there are also non-GHE feedbacks, such as albedo feedbacks (cloud albedo, snow, ice, vegetation, dust / aerosols).

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 initial warming also reduces the surface albedo by melting snow and sea - ice, which likewise constitutes a positive feedback because snow and ice are effective reflectors of sunlight.

In my last comment, «global albedo feedbacks» was meant to refer specifically to global snow / ice albdeo feedbacks.

In the case of albedo this is a positive feedback because the warmer a hemisphere gets the lower its albedo as its ice and snow disappear.

The principal feedbacks are water vapor, snow - ice albedo, clouds, and lapse rate.

Snow increases the albedo of earth, and that may be considered a negative feedback.

The Arctic provides an early indicator of global climate change through feedback systems associated with factors such as the high albedo of snow and ice [Holland and Bitz, 2003].

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..

The main albedo change in the last 60 years is probably ice / snow loss, which is another positive feedback to the change and not independent.

My «Pope's Climate Theory» says that when you melt Arctic Sea Ice, you get Arctic Ocean Effect Snow which increases Albedo and provides negative feedback to the temperature of the earth.

According to the ice - albedo feedback mechanism as the Earth warms more ground and water would be uncovered which would absorb a higher proportion of the incoming solar radiation thus raising the temperature and melting more ice and snow.

In this article I present prima facie evidence that the ongoing natural increase in spring insolation occurring at high northern latitudes, coupled with the positive feedback effect of the resultant snow and ice loss reducing the region's mean albedo over summer, comprises just such a causative agency.

This north / south asymmetry has grown since perihelion was aligned with the winter solstice seven to eight centuries ago, and must cause enhanced year - on - year springtime melting of Arctic (but not Antarctic) ice and therefore feedback warming because increasing amounts of land and open sea are denuded of high - albedo ice and snow across boreal summer and into autumn.

An early application of emergent constraints concerned the snow - albedo feedback.

As I have pointed out in the «essay», what has happened (in an accelerating manner since 1246 CE) is that the insolation reaching far northern latitudes has increased during the first half of each year, and this should be anticipated to cause earlier and more - extensive spring melting of snow and ice, and therefore a progressively - earlier albedo reduction, and therefore more sunlight subsequently being absorbed across spring and summer: the ice albedo feedback effect acting positively (causing warming).

There are, however, also slow feedbacks like the change in surface albedo from the reduction of snow cover that contribute to TCS / ECS.

there is powerful negative feedback to temperature through ice albedo from snow.

The three main criteria for a robust emergent constraint are satisfied: the physical mechanisms are well understood, the statistical relationship between the quantities of interest is strong, and uncertainties in the observed variations are weak, allowing Hall and Qu to constrain the snow - albedo feedback under global warming.

so season by season the perennial snow line advances which is a positive feedback in and of itself as season by season the hemisphere's albedo is reduced -LSB-?]

The influence of spring temperature is particularly pronounced in years that experience low snow pack accumulations, indicating the potential importance of the albedo feedback [3] for the melting of shallow snow.

One example: the feedback through albedo — the reflectivity of the Earth such as can be affected by snow cover.

In order of seniority, the seven feedbacks that seem outstanding are: Water vapour — rising by ~ 7 % per 1.0 C of warming; Albedo loss — due mostly to cryosphere decline; Microbial peat - bog decay — due to rising CO2 affecting ecological dynamics; Desiccation of tropical and temperate soils — due to SAT rise and droughts; Permafrost melt — due to SAT rise plus loss of snow cover, etc; Forest combustion — due to SAT rise, droughts, pest responses, etc; Methyl clathrates [aka methane hydrates] now threatened by rising sea - temperatures, increased water column mixing, etc..

The biggest effects in albedo are the ice and snow reduction with warming and these feedbacks are included.