Sentences with phrase «of ice sheet response»
However, we do not know the functional form of ice sheet response to a large persistent climate forcing.
http://journals.plos.org/
Hansen's paper adds in the possibility of ice sheet response in the relatively near term (centuries, if not decades), which leads to an effective doubling of the sensitivity of climate to our CO2 increase.
(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).
The observational record contradicts the simplifying assumptions used in current models of ice sheet response.
However, we do not know the functional form of ice sheet response to a large persistent climate forcing.
Not exact matches
«Also, since this «tipping point» was reached in the late»90s before warming really took off, it indicates that these peripheral glaciers are very sensitive and, potentially, ephemeral relative to the timescales of response of the ice sheet,» he added.
Our global climate models zoom down to finer and finer resolutions; our satellites reveal remote corners of the globe; we increase our understanding of the response of giant ice sheets and deep ocean currents to a warming planet.
Some scientists have argued that Earth's crust in northern portions of North America is still slowly springing upward in response to the melting of the ice sheet that smothered the region during the last ice age.
«the last glacial period is a good example of a large forcing (~ 7 W / m ^ 2 from ice sheets, greenhouse gases, dust and vegetation) giving a large temperature response (~ 5 ºC) and implying a sensitivity of about 3ºC (with substantial error bars).»
For this subsystem, many of the longer term feedbacks in the full climate system (such as ice sheets, vegetation response, the carbon cycle) and some of the shorter term bio-geophysical feedbacks (methane, dust and other aerosols) are explicitly excluded.
The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).
As we have discussed previously, the last glacial period is a good example of a large forcing (~ 7 W / m2 from ice sheets, greenhouse gases, dust and vegetation) giving a large temperature response (~ 5 ºC) and implying a sensitivity of about 3ºC (with substantial error bars).
Nonetheless, the ice - sheet response to global warming remains an area of what risk analysts call «deep uncertainty».
An additional new feature is the increasingly visible fast dynamic response of ice shelves, for example, the dramatic breakup of the Larsen B Ice Shelf in 2002, and the acceleration of tributary glaciers and ice streams, with possible consequences for the adjacent part of the ice sheeice shelves, for example, the dramatic breakup of the Larsen B Ice Shelf in 2002, and the acceleration of tributary glaciers and ice streams, with possible consequences for the adjacent part of the ice sheeIce Shelf in 2002, and the acceleration of tributary glaciers and ice streams, with possible consequences for the adjacent part of the ice sheeice streams, with possible consequences for the adjacent part of the ice sheeice sheets.
More research work is therefore required to improve the reliability of predictions of ice - sheet response on global warming.
Model studies for climate change between the Holocene and the Pliocene, when Earth was about 3 °C warmer, find that slow feedbacks due to changes of ice sheets and vegetation cover amplified the fast feedback climate response by 30 — 50 % [216].
The potential for unstable ice sheet disintegration is controversial, with opinion varying from likely stability of even the (marine) West Antarctic ice sheet [94] to likely rapid non-linear response extending up to multi-meter sea level rise [97]--[98].
Isabella Velicogna can use that information to «study the mass balance of the Greenland and Antarctic Ice Sheets and glaciers worldwide, in response to climate warming.»
The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).
More specifically, can one define the response time of a particular ice sheet?
... Polar amplification explains in part why Greenland Ice Sheet and the West Antarctic Ice Sheet appear to be highly sensitive to relatively small increases in CO2 concentration and global mean temperature... Polar amplification occurs if the magnitude of zonally averaged surface temperature change at high latitudes exceeds the globally averaged temperature change, in response to climate forcings and on time scales greater than the annual cycle.
That rate is not consistent with a top down melting model and implies dynamic response of ice sheets to warming.
[this is useful, the pre-ice age era, ~ 2.5 — 3.6 million years ago, last time CO2 levels were as high as today] In response to Pliocene climate, ice sheet models consistently produce near - complete deglaciation of the Greenland ice sheet (+7 m) and West Antarctic ice sheet (+4 m) and retreat of the marine margins of the Eastern Antarctic ice sheet (+3 m)(Lunt et al., 2008; Pollard and DeConto, 2009; Hill et al., 2010), altogether corresponding to a global mean sea level rise of up to 14 m.
[Response: Here's a simple back - of - envelope consideration for the future: if the Greenland ice sheet melts completely over the next ~ 1,000 years (Jim Hansen argues in the current Climatic Change that the time scale could be centuries), this would contribute an average flux of ~ 0.1 Sv of freshwater to the surrounding ocean.
Ice - sheet responses to decadal - scale ocean forcing appear to be less important, possibly indicating that the future response of the Antarctic Ice Sheet will be governed more by long - term anthropogenic warming combined with multi-centennial natural variability than by annual or decadal climate oscillations.&rsheet responses to decadal - scale ocean forcing appear to be less important, possibly indicating that the future response of the Antarctic Ice Sheet will be governed more by long - term anthropogenic warming combined with multi-centennial natural variability than by annual or decadal climate oscillations.&rSheet will be governed more by long - term anthropogenic warming combined with multi-centennial natural variability than by annual or decadal climate oscillations.»
From recent instrumental observations alone we are therefore unable to predict whether mass loss from these ice sheets will vary linearly with changes in the rate of sea - level rise, or if a non-linear response is more likely.
[Response: The thickness of the greenland ice sheet is ~ 2000 m on average (don't quote me, that's a ballpark estimate).
«This uncertainty is illustrated by Pollard et al. (2015), who found that addition of hydro - fracturing and cliff failure into their ice sheet model increased simulated sea level rise from 2 m to 17 m, in response to only 2 °C ocean warming and accelerated the time for substantial change from several centuries to several decades.»
«the last glacial period is a good example of a large forcing (~ 7 W / m ^ 2 from ice sheets, greenhouse gases, dust and vegetation) giving a large temperature response (~ 5 ºC) and implying a sensitivity of about 3ºC (with substantial error bars).»
For this subsystem, many of the longer term feedbacks in the full climate system (such as ice sheets, vegetation response, the carbon cycle) and some of the shorter term bio-geophysical feedbacks (methane, dust and other aerosols) are explicitly excluded.
The uncertainty includes our own wavering over our human and economic response, layered over our inability to predict the ice sheet response as a function of CO2 and other climate drivers under our control.
Polar amplication is of global concern due to the potential effects of future warming on ice sheet stability and, therefore, global sea level (see Sections 5.6.1, 5.8.1 and Chapter 13) and carbon cycle feedbacks such as those linked with permafrost melting (see Chapter 6)... The magnitude of polar amplification depends on the relative strength and duration of different climate feedbacks, which determine the transient and equilibrium response to external forcings.
[Response: The ice age calculations are taking the ice sheets etc. as fixed boundary conditions that impart a forcing of their own.
Huybrechts, P. and J. De Wolde, The dynamic response of the Greenland and Antarctic ice sheets to multiple - centure climatic warming.
Of course I can not prove that my choice of a ten - year doubling time for nonlinear response is accurate, but I am confident that it provides a far better estimate than a linear response for the ice sheet component of sea level rise under BAU forcinOf course I can not prove that my choice of a ten - year doubling time for nonlinear response is accurate, but I am confident that it provides a far better estimate than a linear response for the ice sheet component of sea level rise under BAU forcinof a ten - year doubling time for nonlinear response is accurate, but I am confident that it provides a far better estimate than a linear response for the ice sheet component of sea level rise under BAU forcinof sea level rise under BAU forcing.
They offered a conclusion that the «coupling between surface melting and ice - sheet flow provides a mechanism for rapid, large - scale, dynamic responses of ice sheets to climate warming».
[Response: Rain on the flanks is not that uncommon, but enough rain on the bulk of the ice sheet to affect the surface mass balance as much as you suggest is not on.
Ian Joughin made some statements recently [context] that I thought were pretty solid about it being a few centuries before this kind of very rapid sea level rise can take place and that makes sense to me because there are some very important things that you have to do in order to turn on the rapid response of the Antarctic ice sheet — you have to get rid of a couple of big ice shelves for starters.
This result would be strongly dependent on the exact dynamic response of the Greenland ice sheet to surface meltwater, which is modeled poorly in todays global models.Yes human influence on the climate is real and we might even now be able to document changes in the behavior of weather phenomena related to disasters (e.g., Emanuel 2005), but we certainly haven't yet seen it in the impact record (i.e., economic losses) of extreme events.
Of course not, the rise will continue approximately at the current rate, as e.g. the ice sheets will continue to melt due to the elevated temperature — it takes hundreds if not thousands of years until they have finished this response to the past warminOf course not, the rise will continue approximately at the current rate, as e.g. the ice sheets will continue to melt due to the elevated temperature — it takes hundreds if not thousands of years until they have finished this response to the past warminof years until they have finished this response to the past warming.
Surely the IPCC and others at GISS can come up with based on the based available observational evidence and paretial difference equations and paleo climatic data a bloody good guess as to what response ice sheets will have to a known temperature rise come BAU to overall CO2 levels of 450 to 550 ppmv come the centurys end.
I first dug in on behavioral and social science research related to global warming views and responses in 2006, and it quickly became clear that this was the scariest body of science of all — topping ice - sheet instability and even calling into question the utility of my profession.
the non linear has only recently with the advent of powerful computers started recieving proper scientific scrutiny but it is unclear to me that the science of the past 300 years is as useful because the non linear response to forcings etc is messy and not as predcitable it would be fair to say and therefore not scienttifically rigourus enough and hence we end up with known unknowns of being unable to predict future behaviour of such things as ice sheets.
This result would be strongly dependent on the exact dynamic response of the Greenland ice sheet to surface meltwater, which is modeled poorly in todays global models.
Another is lack of theory AND long - term data for other things that matter, like ice - sheet response to warming.
Ricarda Winkelmann et al. modeled the response of the Antarctic ice sheet to a wide range of future carbon emissions scenarios over the long - term (previous simulations have mainly looked at changes that might occur on a shorter timescale).
The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, nonlinear response of ice sheets to a steadily warming ocean.
«Our SIMULATIONS have shown a RATHER significant non-linear response of the air temperature and winds, when we shrinked the area of the ice sheet ``, said physicist Petoukhov.
The fast response from oceans and vegetation (opposite to each other) leads to a change of about 3 ppmv / °C, while the long term response (including ice sheet / vegetation surface area and - deep - ocean current changes) is about 8 ppmv / °C.
«Responses of Ice Sheets to Environmental Changes.»