Sentences with phrase «ice feedback processes»

Several ocean - air - sea ice feedback processes may be operating (Meredith and King 2005; Hanna 1996), though it has been difficult to pin down their relative roles in the observational studies (King 1994; Jacobs and Comiso 1997).

Not exact matches

«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.»

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.

Is there a triggering point beyond which a feedback process is put into action that will accelerate the disintegration of some of the ice sheets?

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).

The factors that determine this asymmetry are various, involving ice albedo feedbacks, cloud feedbacks and other atmospheric processes, e.g., water vapor content increases approximately exponentially with temperature (Clausius - Clapeyron equation) so that the water vapor feedback gets stronger the warmer it is.

Understanding and evaluating sea ice feedbacks is complicated by the strong coupling to polar cloud processes and ocean heat and freshwater transport.

This empirical climate sensitivity corresponds to the Charney (1979) definition of climate sensitivity, in which «fast feedback» processes are allowed to operate, but long - lived atmospheric gases, ice sheet area, land area and vegetation cover are fixed forcings.

Since many of these processes result in non-symmetric time, location and temperature dependant feedbacks (eg water vapor, clouds, CO2 washout, condensation, ice formation, radiative and convective heat transfer etc) then how can a model that uses yearly average values for the forcings accurately reflect the results?

«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.»

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.

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).

Charney sensitivity can be expressed for such forcings as CO2 changes; longer term processes involve CO2 as a feedback (ice ages).

I suppose that for a 3,7 W / m2 forcing, the additional energy of forcing + feedbacks is used for faster processes (melting ice, evaporation, warming of subsurface oceanic layers, etc.) and the new equilibrium is reach on a quite short timescale.

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...»

Note extreme temperature maximums of 5 - 8 °C and that multiple ice, atmosphere and ocean processes help reinforce albedo feedbacks (after Wood et al., submitted).

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..

Section 8.6 discusses the various feedbacks that operate in the atmosphere - land surface - sea ice system to determine climate sensitivity, and Section 8.3.2 discusses some processes that are important for ocean heat uptake (and hence transient climate response).

MacKinnon says the lack of sea ice changes the dynamics of that process by enabling the ocean to absorb more heat, creating a positive - feedback loop that begets more rapid sea ice melting.

• Representation of climate processes in models, especially feedbacks associated with clouds, oceans, sea ice and vegetation, in order to improve projections of rates and regional patterns of climate change.

There are, however, caveats: (1) multidecadal fluctuations in Arctic — subarctic climate and sea ice appear most pronounced in the Atlantic sector, such that the pan-Arctic signal may be substantially smaller [e.g., Polyakov et al., 2003; Mahajan et al., 2011]; (2) the sea - ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other processes and feedback are important; (3) observations show that while recent sea - ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200ice appear most pronounced in the Atlantic sector, such that the pan-Arctic signal may be substantially smaller [e.g., Polyakov et al., 2003; Mahajan et al., 2011]; (2) the sea - ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other processes and feedback are important; (3) observations show that while recent sea - ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other processes and feedback are important; (3) observations show that while recent sea - ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 2009].

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..

Additional positive feedbacks which play an important role in this process include other greenhouse gases, and changes in ice sheet cover and vegetation patterns.

You don't need to go into the details about carbon emissions or chemical processes or quantities of global ice loss or sea level elevations or ocean acidification or the potential feedback loop of tundra methane releases, although there is plenty of available information on all of them.

The approach to the Sea Ice Outlook is a modified Delphi Method (i.e., using questionnaire responses from a panel of indendent experts) that: (1) samples independent expert opinion and rationale on an issue, (2) communicates the results, and (3) iterates on the process with feedback from the expert participants.

The primary triggers for ice ages and inter-glacials are well understood to be changes in the astronomical parameters related to the motion of our planet within the solar system and natural feedback processes in the climate system.

We need greater attention on the strength of uncertain processes and feedbacks in the physical climate system (e.g. carbon cycle feedbacks, ice sheet dynamics)(NRC 2013), as well as on institutional and behavioral feedbacks associated with energy production and consumption, to determine scientifically plausible bounds on total warming and the overall behavior of the climate system (Heal and Millner 2014).

These feedback processes are related to things such as clouds, water vapor, ice, changes in ocean chemistry, and changes in vegetation.

In the present case the feedback should be strong over a timescale of years, while the ice cores tell about slower processes.

Among the global - scale tipping points identified by earth scientists are the collapse of large ice sheets in Greenland and Antarctica, changes in ocean circulation, feedback processes by which warming triggers more warming, and the acidification of the ocean.h

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.

We study climate sensitivity and feedback processes in three independent ways: (1) by using a three dimensional (3 - D) global climate model for experiments in which solar irradiance So is increased 2 percent or CO2 is doubled, (2) by using the CLIMAP climate boundary conditions to analyze the contributions of different physical processes to the cooling of the last ice age (18K years ago), and (3) by using estimated changes in global temperature and the abundance of atmospheric greenhouse gases to deduce an empirical climate sensitivity for the period 1850 - 1980.

We also obtain an empirical estimate of f = 2 - 4 for the fast feedback processes (water vapor, clouds, sea ice) operating on 10 - 100 year time scales by comparing the cooling due to slow or specified changes (land ice, CO2, vegetation) to the total cooling at 18K.

In light of trends showing a likely 3 °C or more global temperature rise by the end of this century (a figure that could become much higher if all feedback processes, such as changes of sea ice and water vapor, are taken into account) that could result in sea level rises ranging from 20 to 59 cm (again a conservative estimation), Hansen believes it is critical for scientists in the field to speak out about the consequences and rebuke the spin offered by pundits who «have denigrated suggestions that business - as - usual greenhouse gas emissions may cause a sea level rise of the order of meters.»

As a reviewer of the Greenland paper in question, the key item is that «The positive - feedback mechanism between melt rate and ice velocity appears to be a seasonal process that may have only a limited effect on the response of the ice sheet to climate warming over the next decades.»

The melting of Arctic ice provides an example of a positive feedback process.

The discovery in ice core records that atmospheric concentrations of two potent greenhouse gases, carbon dioxide and methane, have decreased during past glacial periods and peaked during interglacials indicates important feedback processes in the Earth system.