Sentences with phrase «ice surface albedo»
This estimate does not include the semi-direct effect or the BC impact on snow and ice surface albedo (see Sections 2.5.4 and 2.8.5.6)
https://www.sindark.com/ Not exact matches
The scientists also ran a computer model to simulate the future of Greenland's surface temperature, grain size, exposed ice area and albedo.
The research showed that, compared to pure snow and ice, the reflectivity of the glacier (known as the «albedo») can be reduced by up to 80 % in places where coloured microbial populations are extremely dense, leading to the darkening of the glacier surface.
It confirmed that the mean albedo, or surface reflectivity, of the Arctic ice zone in late summer declined over an almost three - decade period, between 1982 and 2009.
New «benchmark» for loss of reflectivity Another wild card is the loss of the albedo of the ice, or its surface reflectivity.
Pluto and Charon have surfaces dominated by volatile ices, with large variations in color and albedo.
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.
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).
Plotting GHG forcing (7) from ice core data (27) against temperature shows that global climate sensitivity including the slow surface albedo feedback is 1.5 °C per W / m2 or 6 °C for doubled CO2 (Fig. 2), twice as large as the Charney fast - feedback sensitivity.»
Parameters changed in PIOMAS calibration are typically the surface albedo and roughness, and the ice strength.
In addition, since the global surface temperature records are a measure that responds to albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition of various forcings into the oceans / atmosphere / land / cryosphere, teasing out just the effect of CO2 + water vapor over the short term is difficult to impossible.
Other factors would include: — albedo shifts (both from ice > water, and from increased biological activity, and from edge melt revealing more land, and from more old dust coming to the surface...); — direct effect of CO2 on ice (the former weakens the latter); — increasing, and increasingly warm, rain fall on ice; — «stuck» weather systems bringing more and more warm tropical air ever further toward the poles; — melting of sea ice shelf increasing mobility of glaciers; — sea water getting under parts of the ice sheets where the base is below sea level; — melt water lubricating the ice sheet base; — changes in ocean currents -LRB-?)
Equilibrium sensitivity, including slower surface albedo feedbacks, is 6 °C for doubled CO2 for the range of climate states between glacial conditions and ice - free Antarctica.»
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.
Hansen et al. (1993) calculated the ice age forcing due to surface albedo change to be 3.5 + / - Wm ^ -2.
, (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-?)
The model variables that are evaluated against all sorts of observations and measurements range from solar radiation and precipitation rates, air and sea surface temperatures, cloud properties and distributions, winds, river runoff, ocean currents, ice cover, albedos, even the maximum soil depth reached by plant roots (seriously!).
I have a question about the potential albedo feedback effect on a ablating ice sheet surface.
(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).
Surface melt on the ice sheet is constrained by the albedo, but a lake is dark and could absorb much more solar radiation.
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).
Global average temperature is lower during glacial periods for two primary reasons: 1) there was only about 190 ppm CO2 in the atmosphere, and other major greenhouse gases (CH4 and N2O) were also lower 2) the earth surface was more reflective, due to the presence of lots of ice and snow on land, and lots more sea ice than today (that is, the albedo was higher).
I attribute this to rapidly retreating snow cover and sea ice replacing high albedo surfaces with low albedo.
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.
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
Based on evidence from Earth's history, we suggest here that the relevant form of climate sensitivity in the Anthropocene (e.g. from which to base future greenhouse gas (GHG) stabilization targets) is the Earth system sensitivity including fast feedbacks from changes in water vapour, natural aerosols, clouds and sea ice, slower surface albedo feedbacks from changes in continental ice sheets and vegetation, and climate — GHG feedbacks from changes in natural (land and ocean) carbon sinks.
At the same time any bit of ice that sticks up, casting a long shadow, is catching the sun on the surface facing the sun, and may even have a reduced albedo.
When the flux is increased, the planet undergoes a decrease in surface albedo which is due to the melting of the permanent polar ice caps and the reduced seasonal snow cover.
This estimate was refined by Hansen and Nazarenko (2004), who used measured BC concentrations within snow and ice at a wide range of geographic locations to deduce the perturbation to the surface and planetary albedo, deriving an RF of +0.15 W mâ $ «2.
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..
Judith - Apart from the general anthro vs. natural disussion of sea ice, I'm always wondering: has anyone seriously considered / studied the possible anthropogenic contribution from NON-CO2 sources (black carbon soot / aerosol deposits on the ice surface, increasing the albedo, melting the ice faster in the sun)?
This paper analyzes the 420,00 o year Antarctic Vostok ice core data comparing the CO2, CH4, sea level, and surface albedo changes do derive his empirical 3 °C per 4 W / m2 climate sensitivity from the ice core data.
In the Arctic, one familiar feedback effect is sea ice albedo, which measures how well the Earth's surface reflects sunlight.
They also warn that feedback patterns are starting to emerge in the shape of the ice albedo effect: ice reflects heat away from the surface, so as it decreases in extent so warming quickens.
This caused thin first - year sea ice to grow between MY floes thereby decreasing the overall albedo of this surface in the Spring of 2008.
Allen also led his own project on the albedo of snow and ice on the icefield, engaging students to measure the brightness and reflectance of different snow and ice surfaces.
The new study quantitatively assessed how surface ice algae contribute to darkening of the ice sheet, and found the algae reduce the ice sheet's albedo significantly more than non-algal materials, like mineral particles and black carbon.
«Unfortunately, we have no direct information concerning the past global surface albedo from the ice core data.
Indeed as as MarkW has said the extension during the austral winter of the surface of the antarctic ice up to 20 M km ² and 60 ° S would deserve a computation of the total albedo of (floating ice + snow cover)(over the southern and the northern hemispheres), with due account of the elevation of the Sun and of the clouds.
We can make good estimates of global temperature so can estimate planck radiation (on global level), good estimates of albedo from ice extent, reasonable estimates of evaporation and convection from temperature contraints, now try closing that surface budget with GHG.
If these plumes of warm air operated in the same way during the last glaciation as they do know then they would make short work of ice sheets that were hanging around because of the albedo effect, this is possible because not all the northern hemisphere mid latitude land surface was covered with ice throughout the period of glaciation and might explain why glaciations terminate quickly
Seasonal changes in SWR from clear skies have little to do with the surface albedo feedback that will follow global warming (aka ice - albedo feedback).
Furthermore, deforestation in the middle — high latitudes might have amplified Little Ice Age cooling by exposing more snow and increasing surface albedo (107, 110, 111).
Climate forcings due to past changes in GHGs and surface albedo can be computed for the past 800000 years using data from polar ice cores and ocean sediment cores.
In the real - world, up to a third of it is reflected back to Space from light - colored surfaces (albedo) such as snow, ice, clouds, and the white roof of Energy Secretary Chu's home: ^).
The temporal variation of the GHG plus surface albedo climate forcing closely mimics the temporal variation of either the deep ocean temperature (figure 6) or Antarctic temperature [5,31] for the entire 800000 years of polar ice core data.
Albedo change due to LGM — Holocene vegetation change, much of which is inherent with ice sheet area change, and albedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foAlbedo change due to LGM — Holocene vegetation change, much of which is inherent with ice sheet area change, and albedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foalbedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foalbedo climate forcing.
To avoid long response times in extreme climates, today's ice sheets are assigned surface properties of the tundra, thus allowing them to have a high albedo snow cover in cold climates but darker vegetation in warm climates.
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.
Glacial — interglacial oscillations of the CO2 amount and ice sheet size are both slow climate feedbacks, because glacial — interglacial climate oscillations largely are instigated by insolation changes as the Earth's orbit and tilt of its spin axis change, with the climate change then amplified by a nearly coincident change of the CO2 amount and the surface albedo.