h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi fellow SExperts.

I asked this once briefly in a conversation here and got no reply. So now I ask it again formally.

Looking at this map http://www.athropolis.com/map2.htm

It looks to me that parts of Greenland are nearly as far South as, say The Shetland Islands. Also, many parts of both North America and Asia are as far north as much of Greenland.

So why does Greenland have such an extensive ice sheet, whereas Northern Canada and Russia do not?

Not they aren't under arctic weather conditions if you take my meaning, more why aren't they under 11,000 ft of ice like Greenland?

I think Greenland's middle bit is at quite a high elevation, unlike (I think) t'other two. The Labrador current pushes cold water down the west coast as well, which might help.

Dunno though. question

Would water currents (Gulf Stream etc) have any effect on it?

Quite possibly but the warm gulf stream more or less goes past Greenland does it not?

Mind you there is that theory that the gulf stream cutting off would plunge us into a new age of ice-sheets.

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Dunno, but there must be other currents that affect it.

I've heard of that theory, very imo

isn't this because of the snowball earth effect

the ice reflect the heat away and greenland has been left by the retreating ice surrounded by sea, whereas the other land masses have land to the south of then, which warms up and melts the ice to the north, producing the retreating ice effect?????

every year the snow falls and then retreats as the land warms, yet greenland is surrounded by sea which does not warm as fast and as much as the land

That sounds feasible. Thanks

I'm not sure about that - do large bodies of water like seas and lakes not 'store' heat which they give off over colder months? Generally areas surrounded by water experience less ice and snow than inland areas if everything else is equal, right?

The south side of the main peninsula of Alaska also has sea to the south, but it's not covered by a giant icecap.

Looking at the green treeline, er, line I favour Pedro's (post 2) altitude suggestion.

No?

the treeline also is indicative of land warming, trees soak in heat because they are dark accelerating melting in the area trees are, the coast of alaska is above the treeline???

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Having read the wikipedia article on Greenland, I've discovered that the centre of Greenland is quite the opposite of highly elevated. The weight of the ice has depressed it around 300 ft *below* sea level.

Water heats and cools slower than land, so maritime areas experience warmer winters and cooler summers than continental ones. It seems reasonable that this effect would also help to preserve Greenland's ice - it never gets really warm around it to melt the ice.

A lot of the coastal areas aren't covered in ice though. I read the wiki article too; it says it's thought if the cap melts there'll be at least 3 islands.

> it never gets really warm around it to melt the ice.<

Yes but north Canada and Russia both have extensive regions of tundra do they not? I.e. permanently frozen ground...

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the tundra is not permanently frozen, or nothing would live there

the tundra is the strip of land above between the tree line and the ice cap,

the tundra does have a permafrost layer

frozen ground a little way below the surface where the suns heat does not reach and so is permanently frozen,

the surface melts and provides enough of a suitable enviroment for plants to grow and animals to graze

Ah, OK, I misunderstood what tundra was. Thanks.

I just got around to looking at the map posted in the original question. I had assumed it would be a standard map, but it has other details on. It's interesting to see how irregular the icecap and the July 10 degree isotherm are - Greenland is not the only anomaly. Presumably it can all be explained in terms of land/sea and ocean currents.

Saw this and just thought of this thread.

Apparently the icecap started 3mya when CO2 concentrations fell.

http://www.sciencedaily.com/releases/2008/08/080827163818.htm