31
I'm not quite sure if the question is asking about glacial, ice ages, or snowball Earth, and whether it's about the onset or end of a glacial period. I'll try to hit all three.
Ice Ages and Milankovitch Cycles
Ice ages are long spans of time that marked by periods of time during which ice reaches far from the poles, interspersed by periods during which the ...
26
If there is enough water underground, in a sealed reservoir (like under the concrete in the picture), as that water freezes, it will expand, putting pressure on what ever water is left unfrozen. That water will be squeezed out through what ever cracks it can find - in this case, upwards. Because the water is already near-freezing (perhaps even slightly below,...
25
Sea level has a strong seasonal signal. The annual variability is less than the daily changes associated with tidal forcing in most locations, but still can be on the order of 5-10 cm (maximum values about 15 cm).
The causes of the seasonal fluctuations are mostly associated with seasonal changes in wind intensity and patterns, changes in temperature that ...
22
The short answer is: BECAUSE THE ICE IS BLUE.
Now we have to explain why it seems perfectly transparent on ice cubes and industrial ice blocks.
It has to do with the fact that most transparent materials are not perfectly transparent, and instead absorb (and/or scatter) part of the light that hits them. And when the transparency is better for one specific ...
19
I think you're slightly confused by some of the terminology. (Caveat: I'm a geophysist, take anything I say with a grain of salt!)
We're currently in an interglacial during a prolonged period of icehouse climate (most of the Cenozoic).
During most of the Earth's history, the overall climate tends to be much warmer and more stable on the million-year scale....
18
21.7%, by my calculations (338 / 1556 holocene-active volcanoes). I calculated perennial snow by combining 6 weeks of MOD10A2 data from winter and summer weeks in 2014 to figure out which pixels had snow both in the summer and the winter. My source code for that is available as a gist (an older version accidentally classified cloud as snow; that's been fixed)...
17
Forming of coastline
During the last ice age, the North Sea was dry. When the ice melted sea levels slowly started to rise again and due to tides and currents
a barrier of dunes was formed along what approximately is today's coast line. This created an area of land that fell dry during ebb-tide and flooded during high tide (this can still be seen in the '...
17
Indeed some glaciers are growing and gaining mass due to increased precipitation (in part due to climate change and enhanced atmospheric water content). But that's the case only for glaciers in very cold places, like East Antarctica, where most glaciers appear to be growing at increasing rates (1,2). But unfortunately West Antarctica is pretty much a desert; ...
16
The question is requesting an answer that has no practical application. So rather than improving on some hypothetical calculation, I will describe the problem and hopefully make the difficulty providing a real answer to a time frame clear.
First: "polar ice" Antarctica is located in a polar position and consists of a multi-km thick ice sheet. The Arctic is ...
15
Of course it isn't "absurd", and looking at the ball-park energy budget figures you'll see why:
First, I don't think anyone is claiming the Earth is completely frozen. More of a "slushy at the Equator" scenario. But let's assume an average 1 km thickness of ice for arguments sake (i.e. probably an exaggeration although polar ice would be thicker).
The ...
14
Such forms tend to be created by glacial activity, which, ahem, the ice-covered continent is known for. Much discussion of this in the related question in Skeptics: Are there three pyramids in Antarctica?
Here's the generic answer in Wikipedia:
A pyramidal peak, sometimes in its most extreme form called a glacial
horn, is an angular, sharply pointed ...
13
Some background. The idea of towing ice bergs to provide a source for fresh water in dry climate zones was first proposed in the 1970s by Weeks and Campbell (1973) and Hult and Ostrander (1973). This sparked interest that resulted in several studies published in conferences (Husseiny, 1980; IGS, 1980). The focus of the work was manly on the wastage of ice ...
13
What you see are ice bergs frozen into a sheet of sea ice. The "chunks" are the ice bergs. Ice shelves are fed by two sources, ice from the interior of the ice sheet and ice formed by compaction of snow accumulating on the shelf itself. This means that a shelf can have very different dynamic regimes. Parts of shelves where ice is mostly formed locally will ...
13
Essentially, we can't. At a meeting some years ago, different specialists tried to define the onset of glaciation and found that each (sub-) discpline had their own definition. An oceanographer boldly stated the glaciation started 2000 years ago since a change in the Greenland ocean currents occurred at that time which was observed to also change before the ...
13
The key is with wind-drifting. The predominant westerlies cause snow to drift into protected places. We should perhaps recall that glaciers exist because they are essentially snow-catchers in a landscape that is sufficiently suitable for some of the snow to survive the summer melt period. The drifting and depositing of snow on the eastern side of mountains ...
13
The straight answer is no. The definition of a glacier requires the body to be of ice and snow, to move and deform under its own weight. If the body is pure ice the pressure needed to make ice deform corresponds to about 30-40 m of ice pressure.
The definition makes any body not consisting of ice and snow not a glacier. As an example, so-called "saltiers" ...
12
Antarctica is the ice sheet (cap) that will contribute most IF it would melt completely. The 2013 IPCC report (Ch. 4, the Cryosphere) provides an estimate of 58.3 m of sea level equivalent (sle). Greenland would if completely wasted away provide 7.36 m sle. Remaining glaciers provide an additional 0.41 m sle. The likelihood of Antarctica completely wasting ...
12
This is needle ice which forms when moist soil freezes, for example during a cold night. Freezing starts at the ground surface and as ice is formed moisture gradients develop which draws water to the freezing front and growth continues. Ideal conditions may be a sub-freezing night after a rainy day or a sub-freezing night after a day of snow melt.
According ...
12
There is some scope for continuing debate because quantifying the various components of the ice/snow/water balance are fraught with difficulty, and many of the estimates have error bounds which approach the magnitude that is being measured. However, a good best estimate, subject to continuing research, is given in:Is Antarctica losing or gaining ice?
This ...
12
It's a glacier, it this case the Baltoro Glacier in Karakoram, Pakistan. The road-like pattern is formed as the glacier slowly flows towards lower altitude from a nearby ice-cap or accumulation zone. Rocks and dirt is transported both within the ice and on the surface.
With a closer look, the surface is rarely smooth, but often deep trenches, cravasses, ...
12
It depends where, the continental landmasses at higher latitudes would be covered by massive ice sheets. Therefore the life in the sections of the US and Europe that are close to the Ice sheets would have conditions similar to what is life in Greenland today. The map would look like this:
(Image taken from planetaryvisions.com)
And the summers would be ...
11
IceCube was initiated as the Antarctic Muon And Neutrino Detector Array (AMANDA) project. Since the sensor array involved drilling deep holes vertically into the Antarctic ice sheet by melting ice, no ice cores were retrieved. The bore holes have, however, been used to construct temperature profiles through the Antarctic ice sheet published in a paper in ...
11
Ice can grow up from the ground in the form of needle ice. The formation requires sufficient moisture in the ground. According to the National Snow and Ice Data Center (NSIDC) site needle ice can grow up to 40 cm in length. Needle ice are thin crystals of ice and has a very distinct look. A search on Needle Ice provides a wealth of examples of needle ice, ...
11
This is a non-trivial issue. When you look at volume change of a glacier, you typically subtract two digital elevation models to obtain the difference between the two. First, you must differentiate between ice sheets where ice berg calving reduces volume and more ordinary glaciers with melt processes. There are of course calving glaciers as well so it is ...
11
This is a large glacier calving event. Calving occur at the front of the glacier, probably a very wet (and likely warm based) glacier where a considerable amount of water is flowing out of the system (thus from the glacier to the sea). The amount of water is important as it can accelerate the ice flow speed on the valley floor, enabling the breaking of big ...
10
There are two ways in which earthquakes could affect the Antarctic ice sheet, either by occurring on the Antarctic continent or by occurring elsewhere and sending tsunami-type waves towards the ice sheet/continent.
Seismic activity occurs all the time on Antarctica. Particularly the West-Antarctic Ice Sheet (WAIS) is located over seismically active zones ...
10
I will answer mostly from archaeological perspective; I don't know much about the paleoclimatology before the first people started to produce stone tools. I know just some basics of other disciplines where they affect human (pre)history, but it might help.
First, even though longer and older cold periods are also refered as "ice ages", most people don't ...
10
Don't rest so easy, ravenspoint.
The Laurentide ice sheet at its maximum extent was larger than the Antarctic ice sheet is now. The bulk of that ice sheet melted in two pulses of 2000 years each, separated by the ~1000 year long Younger Dryas. During the first pulse, the Laurentide lost 5400 km3 of ice pear year. During the second pulse, it lost ice at an ...
10
There's no contradiction. Firn is an intermediate form between snow and ice, with a density between that of snow and ice.
The frozen fluffy stuff that falls from the sky -- that's not ice, it's not firn. It's snow. It's also not very dense, typically less than 0.5 grams/cm3. As the snow sits and gets compressed by snow atop it, some of the gas gets squeezed ...
Only top voted, non community-wiki answers of a minimum length are eligible
