How Much Land Ice Melts Per Degree Of Temperature Rise?

[David H]

The only ways sea level rises is from land ice melting and thermal expansion. Using this formula how much will sea level rise per degree C the temperature rises to melt mainly the Greenland ice shelf as the other land ice is too cold in Antarctica? I haven't been able to find a graph but it must be fairly easy to calculate.

[-SharonA-]

If fairly easy........... why have you not done so?

[David H]

You would need the amount of Greenland ice (and a little more on land), and then how much would melt where it is around freezing currently. Anywhere colder would stay frozen till the next rise per degree, then after adding the thermal expansion per 1C rise you should be able to see the actual sea level rise based purely on available ice plus expansion. I haven't found one online and if I knew the details I would have done it myself. Maybe a geology student would have access to such figures at university.

[jim360]

Sea level rise due to the melting of Greenland's ice will be, I believe, fairly small, something in the region of seven metres on average if it all melted, but that rise would be dragged out over centuries or even millennia (at current rates of warming). So over the next century you would be looking at something in the region of a few centimetres or so due to Greenland.

From Antarctica it would also be a few centimetres (at present rates) -- and the main one is, as you'd guessed, from thermal expansion. Based on some rough back-of-the-envelope calculations I think the rough conversion is something in the region of 1m per degree Celsius of global average temperature rise, but it isn't at all easy to calculate and various models give different ranges (also depending on the amount of time allowed between measurements of the sea level).

Since 1900, the sea level has risen about 20cm, and about half of that was since 1990. So on current rates you could feasibly expect sea level to rise by about a metre by the end of the century.

[vetuste_ennemi]

Does that mean, then, Jim, that Mauritius and the Maldives will not in the foreseeable future go the the way of Atlantis? And that we will be able to carry on driving cars and heating our homes using fossil fuels?

[jim360]

Even a rise in sea level of a metre would be enough to see the Maldives largely submerged. And besides, this is only at present rates, which themselves can be expected to change (and, more than likely, increase) in the future. In practice, the polar ice sheets will take a very long time to melt, it is true, but it's been suggested that the process, once it gets going, may be virtually irreversible.

I do hope, therefore, that you weren't planning to use my post as grounds to advocate a laissez-faire approach to human activities related to climate?

[vetuste_ennemi]

I'm afraid, Jim, that was exactly my uncunning plan.

[jim360]

I suspected as much.

In short: no. Just, no. It's a bad way of looking at things. The most likely scenarios suggest that the effects of human-driven climate change won't have an appreciable effect within our lifetime, but that's not even remotely the point.

[vetuste_ennemi]

Mind you, adopting sensible measures to save the environment against a real or perceived threat will be conducivee to useful social and moral outcome, namely "equality". Third world agrarian societies (many of them African) will be denied any escape, while advanced industrialised economies will revert to their subsistence past. It's a lose-lose, sorry , win-win situation, isn't it?

[vetuste_ennemi]

By the way, I see there's a UC thread. Just about to watch it it. Apparently the high-fivers are on again. (Good team. Shame about a Cambridge college losing to Bangor. How long ago was that? And isn't life a witch!) Got me pen and paper out. Only on my second large Bacardi at the moment.

[jim360]

It's a rather poor way of looking at things, though, isn't it? Just repeats the mistakes that led us here in the first place, ie short-termist interests destroying long-term prosperity.

Don't let

[jim360]

Don't let money distract you from saving the world, was what I was trying to post.

Also, yes. Whoever played for that Cambridge college must be so embarrassed about that.

[vetuste_ennemi]

Shh, Jim. That's our little secret.

[David H]

Thanks Jim, that's the only projection I've seen, although it implies the rise can't be linear as the last degree C added under a foot, so something would need to happen I must have missed to make the next C three feet (sorry, no speaka da metric). Unlike melting ice thermal expansion should be constant and as such definitely linear and I am surprised no such graphs exist if so as they are as reliable as astronomical charts.

[jim360]

I'm not so convinced that it should be linear. Even if you made the simplest assumption that the oceans behave like an ideal gas it still wouldn't be linear, most likely.