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I understand that Antarctica plays a large role in driving ocean currents and thus the climate of the planet. However, I'm curious what the world would be like if there was no Antarctic landmass at all and the only thing at the southern polar reaches of the planet was water?

I'm sure there would be less penguins, but how else would the world be different?

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  • $\begingroup$ This is pretty broad. Is there anything specific you'd like answerers to focus on? $\endgroup$ – HDE 226868 Sep 30 '15 at 23:27
  • $\begingroup$ Yeah that's true, I kind of wanted to keep it quite broad as I don't really have any idea of what the outcome would be and I'd love to see where people go with their answers. I hope that's acceptable but let me know if you think I should refine my question a bit. $\endgroup$ – PenguinMan Sep 30 '15 at 23:55
  • $\begingroup$ Well, we wouldn't have to worry about the cthulhu. See The Mountains of Madness. $\endgroup$ – JDługosz Oct 1 '15 at 8:02
  • $\begingroup$ We'd have fewer Emperor penguins. Quite a lot of penguins have never even seen snow! $\endgroup$ – Joe Bloggs Oct 2 '15 at 13:17
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The world has been how you describe (ocean at both poles) for most of its geological history, with fossils providing quite good evidence for its climate over the last 500My or so. We can therefore answer the question of how it would be in one word: warmer! Think steaming tropics too hot for any but very small mammals to survive (but good for very large crocodiles), and a Mediterranean climate close to the poles. Probably also large expanses of desert too hot for any life at all (like Death Valley warmed up a bit). Precise details of climate and ocean circulation are of course determined by the configuration of continents as well as the absence of ice. Which configuration is quite markedly changed by a 200ft rise in sea-level -- say goodbye to Florida and most of the Missisippi basin, for starters.

There is a positive feedback loop and a lock-in effect. The positive feedback is that ice is highly reflective. The more ice, the more sunlight is immediately reflected straight back into space. So advancing ice causes global cooling leading to an ice age, and retreating ice causes global warming leading to more ice melting. (Throw in methane clathrates melting as the ice covering them melts, and there's a good chance of methane-induced run-away global warming over mere centuries). The lock-in is that once all the ice is gone, there's nothing feeing freezing cold water into the oceans, and the huge reserve of cold 4C water at the bottom of the oceans starts to warm up. Over a few tens of millions of years, the ocean becomes a pretty huge reservoir of warmth.

So why won't the human race stop burning stuff? We may already have put ourselves on a one-way trip to a planet with sea-level 200 feet higer, and at least four-fifths of the remaining land area uninhabitably hot or humid.

If you think that's pessimistic: this planet is very close to the inner edge of Sol's "Goldilocks zone". The real ultra-pessimists think, maybe not inside it at all any more (the sun is gradually getting hotter as it ages), so that once all the ice melts, the global warming effect of all the extra water vapour in the atmosphere will overwhelm the added cooling caused by increased cloud cover, and the planet will end up as a cooler version of Venus.

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  • $\begingroup$ I'm not sure how the rant on anthropically driven warming adds to this answer, otherwise good point about the geological record! $\endgroup$ – Joe Bloggs Oct 2 '15 at 13:16
  • $\begingroup$ I felt it gelled with the OP's "I'm sure there would be less penguins", but reading it again, agree it's a bit of a rant. $\endgroup$ – nigel222 Oct 2 '15 at 14:31
  • $\begingroup$ Burning stuff is cool. Even hippies go to Burning Man. Nobody denies this. $\endgroup$ – Oldcat Oct 3 '15 at 0:11
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The South Polar Ice cap is a huge reservoir of cold material that drives the habitability of the Southern Hemisphere down relative to the Northern. For example, the Arctic Circle to about 50 degrees North contains a lot of habitable country. In the South, Tierra Del Fuego is virtually uninhabitable and only specialists live on the Antarctic Circle.

Removing that would make that hemisphere much more temperate overall, especially at high latitudes.

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    $\begingroup$ There's another reason the Southern hemisphere climate is harsher: Earth's axial tilt and slightly eliptical orbit. The Northern hemisphere gets Winter when the Earth is closer to the Sun, the Southern when Earth is further away. This makes the Southern hemisphere Winter-Summer climate range greater than Northern hemisphere range. But yes, the Antarctic continent is also a big influence. $\endgroup$ – nigel222 Oct 1 '15 at 23:31
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Polar ice caps form on land. If there were no land close enough to the South Pole, there would be no South Pole ice cap.

The lack of South Polar ice cap would reduce the ocean temperature differential which would probably weaken a variety of southern ocean currents. I'm not sure what climactic effects this would have.

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    $\begingroup$ Downvoted. Please explain the North Pole ice cap. $\endgroup$ – WhatRoughBeast Oct 1 '15 at 15:52
  • $\begingroup$ Ice flows in from the surrounding land mass. $\endgroup$ – Jim2B Oct 1 '15 at 16:21
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    $\begingroup$ North pole ice cap is a thin skin of ice floating on water, and only possible because the Arctic "ocean" is a shallow sea almost entirely surrounded by permafrosted land and ice-caps. Geological history shows that there's no ice on the planet unless there's a continent at or near a pole. $\endgroup$ – nigel222 Oct 1 '15 at 23:18
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    $\begingroup$ Stranger and stranger. If, at some time, there is no continent near the pole, there will be no geological evidence that there was an ice cap, regardless of whether there was one or not. And the Marinoan Glaciation (ca 650 My) occurred when there was nothing near the north pole. And you seem to be saying that the north pole ice cap, isn't a "real" ice cap, but rather a "thin skin". If you want to define a "real" ice cap as having some predefined thickness, do so - and justify it. Until then, a year-round ice covering of a pole counts, regardless of thickness. $\endgroup$ – WhatRoughBeast Oct 2 '15 at 1:15
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    $\begingroup$ What you assume I am saying is not what I'm saying. The North Polar ice cap began as glacial outflows from a landmass. From there it accreted the rest. Ice can form in the oceans but without either land, currents, wind or thick glacial flows holding it in place, it would quickly circulate away from the cold and melt. You only get large polar caps when you have a land mass near the pole (South Pole) or something holds that ice in place (North Pole). If an ocean the size of the Pacific were at one of the poles, there would be no polar ice cap. $\endgroup$ – Jim2B Oct 2 '15 at 1:40

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