Sentences with phrase «ice feedback at»

This sea ice feedback at 18K is consistent with the smaller fsnow / ice ∼ 1.1 in the So and CO2 experiments, which applied to a warmer earth with less sea ice.

Not exact matches

«Clouds are one of the major feedbacks in cooling and heating the surface» of the ice, said Nate Miller, an atmospheric science graduate student at the University of Wisconsin, Madison.

At that temperature, the study says, enough ice - sheet melting causes a positive feedback loop that leads to more melting and rising seas.

«Instead of emerging at the surface, much of that heat is melting the ice shelves,» Hansen says, producing more fresh water and amplifying the feedback.

The new model is the first to document and quantify this new feedback — one that is not accounted for in climate models, says Jason Box, an ice scientist at the Geological Survey of Denmark and Greenland in Copenhagen, who has documented rising impurities at a local scale during field campaigns.

Publication: Antarctic ice shield discharge driven by atmosphere - ocean feedbacks at the Last Glacial Termination, DOI: 10.1038 / srep39979

Let's just mention the ice - albedo feedback, which is very different at (hypothetically) e.g. 100K surface temperature with probably «snowball earth» and at 300K with no ice at all.

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!

A 2008 study led by James Hansen found that climate sensitivity to «fast feedback processes» is 3 °C, but when accounting for longer - term feedbacks (such as ice sheet disintegration, vegetation migration, and greenhouse gas release from soils, tundra or ocean), if atmospheric CO2 remains at the doubled level, the sensitivity increases to 6 °C based on paleoclimatic (historical climate) data.

CO2 is no more a feedback than water vapor, look at the ice core data.

In this case, incursions of circumpolar deep water onto the continental shelf are melting the ice stream at its base and encouraging grounding line recession, which results in a positive feedback loop and further grounding line recession.

Meanwhile, over thousands of years feedback and re-feedback CO2 enters the atmosphere, and we're at a supercharged version of emerging from an ice age.

To all farmers - at - heart: Pure Farming 2018, a new farming game from Techland Publishing and developer Ice Flames, has just hit stores worldwide, and also revealed extensive plans for post-launch content, heavily influenced by community feedback.

In the future, I would look forward to another Sonic Boom title if Sanzaru Games was once again at the helm, provided they can be just as effective in incorporating feedback for that new game as they have proven to be with Fire & Ice.

One feedback that I have only rarely heard discussed is the effect that the drop in elevation of, for example, the Greenland Ice sheet will have on the melting at the top.

Perhaps all of this newly freed up ice - cold water at the poles is temporarily acting as a negative feedback, but as it absorbs more of the solar radiation, over time, it will transform into what we rightly think: a predominately positive feedback system, rapidly intensifying the warming.

Hansen seems to argue for a maximum rate of SLR, under BAU forcing, of at least 4 - 5 meters per century, somewhere in the coming centuries (including a negative feedback he calls the «ice berg cooling effect»).

The characteristic flattening of this trajectory, at first order, arises from the fact that there is an increasingly negative (damping) feedback as the sea ice thins described by Bitz and Roe (2004) and Armour et al. (2011).

How do the complex feedbacks change atmospheric circulation patterns, and the interaction of these patterns to changes in ice cap topography (e.g. at the LGM)?

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).

Whilst this is the basic cause of the cyclical nature of the ice age and the warmer inter ice age climate of the earth in the last few million years at least, there are natural «feedbacks» in the earth which then exaggerate this climatic change.

What I meant (what I thought you meant) by Chuvian runaway was a runaway of an extent more limited (covering a smaller range of temperatures that can't be at equilibrium) than the big ice - albedo and H2O - vapor greenhouse runaway feedbacks of snowball and «steamball» conditions.

In LGM simulations land albedo changes are prescribed (at least in regards to ice sheets and altered topography due to sea level; there are feedback land albedo changes) so are a forcing, whereas sea ice is determined interactively by the model climate, so is a feedback in this framework.

(57j) For surface + tropospheric warming in general, there is (given a cold enough start) positive surface albedo feedback, that is concentrated at higher latitudes and in some seasons (though the temperature response to reduced summer sea ice cover tends to be realized more in winter when there is more heat that must be released before ice forms).

For example, if the Earth got cold enough, the encroachment of snow and ice toward low latitudes (where they have more sunlight to reflect per unit area), depending on the meridional temperature gradient, could become a runaway feedback — any little forcing that causes some cooling will cause an expansion of snow and ice toward lower latitudes sufficient to cause so much cooling that the process never reaches a new equilibrium — until the snow and ice reach the equator from both sides, at which point there is no more area for snow and ice to expand into.

A typo in mine at # 25 is where 40,000 m3 should read 400,000 m3, and an addendum is the reference for the forcing from the Albedo Loss feedback shown in the satellite record: «Observational determination of albedo decrease caused by vanishing Arctic sea ice» See: http://eisenman.ucsd.edu/publications/Pistone-Eisenman-Ramanathan-2014.pdf

Once the ice reaches the equator, the equilibrium climate is significantly colder than what would initiate melting at the equator, but if CO2 from geologic emissions build up (they would, but very slowly — geochemical processes provide a negative feedback by changing atmospheric CO2 in response to climate changes, but this is generally very slow, and thus can not prevent faster changes from faster external forcings) enough, it can initiate melting — what happens then is a runaway in the opposite direction (until the ice is completely gone — the extreme warmth and CO2 amount at that point, combined with left - over glacial debris available for chemical weathering, will draw CO2 out of the atmosphere, possibly allowing some ice to return).

I'm not saying this is like arranging deck chairs on the Titanic as it either A) more quickly or B) more slowly heads toward the ice berg, but I think we (as people, if not as scientists) should now start being concerned about reaching milestones in the warming (whether we reach them faster or slower) at which positive feedback loops kick in — even if this is difficult scientifically to quantify or prove.

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).

[Response: That is a positive feedback that acted during ice age cycles: when it got warmer at the end of an ice age, this led to release of stored CO2 from the deep ocean, thus raising atmospheric CO2 levels.

The snow and ice feedback is generally positive and becomes very large at very cold temperatures; obviously it approaches zero when the temperature is sufficiently warm that very little snow or ice remain and when they occur when and where there is little solar radiation to reflect.

It is true that during ice ages the oceans took up more CO2 and that is why there was less in the atmosphere, and during the warming at the end of glacial cycles that CO2 came back out of the ocean, and this was an important amplifying feedback.

Even prior to any large feedback involving the ice sheets or carbon cycle, the actual rise in sea - level continues to be at the top edge of the envelope of the IPCC's predictions.

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...&raquat 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...&raquAT 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...&raquAT 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...&raquat high northern latitudes...»

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, etcat 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, etcAT 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, etcAT 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..

The findings reinforce suggestions that strong positive ice — temperature feedbacks have emerged in the Arctic15, increasing the chances of further rapid warming and sea ice loss, and will probably affect polar ecosystems, ice - sheet mass balance and human activities in the Arctic...» *** This is the heart of polar amplification and has very little to do with your stated defintion of amplifying the effects of warming going on at lower 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...»

Determining the mechanisms and feedbacks involved in climate change at the end of the last ice age therefore requires an understanding of the relationship between the southern margin ice retreat and connected meltwater events to atmospheric and sea surface temperatures, ice - rafting Heinrich events, sea level rise, and atmospheric greenhouse gas concentrations.

So your scientific intuition rebels at the thought of runaway positive feedback (like that which causes the rapid transition from ice age to interglacial which is so well established), but it doesn't rebel at the thought that somehow, every scientist since 1922 has failed to notice an allegedly major flaw in our understanding of the greenhouse effect?

Typical temperature reconstructions for the late Pliocene however [see one at the top of this story - 3.3 - 3.0 Ma] already show an Earth in which a warmer climatic state is indeed [through for instance ice albedo feedbacks] relatively strong around the poles, and (on average) weaker around the equator, exactly the pattern that is monitored under the current climate warming.

Arctic sea ice extent reconstruction - Kinnard et al. 2011 Sea ice albedo feedback - NASA Polar jet stream - NC State University Greenland ice sheet surface melt - NASA Permafrost distribution in the Arctic - GRID - Arendal Atmospheric methane concentration - NOAA ESRL Russia plants flag at North Pole - Reuters

The resulting enhanced loss of summer and winter sea ice resulted in feedbacks, associated with Arctic Amplification, which has raised Arctic air temperatures at a rate twice the global average.

Given that this feedback alone gave that warming input while realized AGW was between ~ 0.4 C and 0.85 C, and given that it is inherently non-linear with increasingly juvenile arctic sea ice being increasingly vulnerable to melting, it seems fairly clear (to me) that as «anthro warming» rises towards ~ 2.4 C the sum of the feedbacks» outputs would inexorably rise to offset our best efforts at Emissions Control.

When ice age cycles are concerned Milankovitch cycles and feedback through CO2 are surely involved, but — Milankovitch cycles are weak, at least on global level.

Oh, and according to the ice core data, at a certain level CO2 reaches saturation and becomes a negative or neutral feedback evidenced by falling temperature / rising CO2.

Orbitals, bottom water formation in the northern Atlantic and runaway ice feedbacks is a more likely chain of causality at a 100,000 year cycle.

Armour says this is most likely due to feedback mechanisms that have yet to take off fully, such as the increased absorption of sunlight at the poles as reflective ice sheets and sea ice melt away.

At low points — ice sheet growth become a runaway feedback leading to glacials.

At that level, the world risked initiating feedbacks in the climate system, such as the melting of ice sheet area, that could trigger irreversible warming out of humanity's control.

In recent times (the last few million years at least), we've seen rather wild swings in temperature called ice ages that seem to indicate that there is a fair range of temperatures where the net feedback is positive, rather than negative.