Current computer models suggest that the Arctic will be entirely ice-free during summer by the year 2070 but some scientists now believe that even this dire prediction may be over-optimistic, said Professor Peter Wadhams, an Arctic ice specialist at Cambridge University.

"When the ice becomes so thin it breaks up mechanically rather than thermodynamically. So these predictions may well be on the over-optimistic side," he said.

As the sea ice melts, and more of the sun's energy is absorbed by the exposed ocean, a positive feedback is created leading to the loss of yet more ice, Professor Wadhams said.

"If anything we may be underestimating the dangers. The computer models may not take into account collaborative positive feedback," he said.

Sea ice keeps a cap on frigid water, keeping it cold and protecting it from heating up. Losing the sea ice of the Arctic is likely to have major repercussions for the climate, he said. "There could be dramatic changes to the climate of the northern region due to the creation of a vast expanse of open water where there was once effectively land," Professor Wadhams said. "You're essentially changing land into ocean and the creation of a huge area of open ocean where there was once land will have a very big impact on other climate parameters," he said.


http://news.independent.co.uk/world/science_technology/article312997.ece

I've been doing a lot of research about this topic lately because I'm leaving for Canada to study polar bears on Sept. 30. It's truly frightening to consider all of the crazy chain reactions and positive feedback situations that climate change can cause.

It be so hot here. Dang.

I've been doing a lot of research about this topic lately because I'm leaving for Canada to study polar bears on Sept. 30.


How facinating!

It's truly frightening to consider all of the crazy chain reactions and positive feedback situations that climate change can cause.

I too get very scared reading about these recent developments, everything is happening so quickly, with the sea ice melting and the permafrost melting. I didn't think these things would happen during my lifetime. And still so many people talk about global warming as something that might happen in the future! I just want to shake them, or slap them, or something! Wake up! It's happening now! We're going to have to deal with it now!

I too get very scared reading about these recent developments, everything is happening so quickly, with the sea ice melting and the permafrost melting. I didn't think these things would happen during my lifetime. And still so many people talk about global warming as something that might happen in the future! I just want to shake them, or slap them, or something! Wake up! It's happening now! We're going to have to deal with it now!

Yup.

I've also been wondering about the wisdom of rebuilding New Orleans considering much of the city is below (current) sea level.

I think that the planning of new developments, cities etc. is going to need a lot of thought, taking the seeming inevitability of rising sea levels into account.

Our culture will not admit that the forces of nature and physical reality are stronger than we are, that's why New Orleans will be rebuilt - with taller levees. To prove "we won't be beaten by Nature!" Our culture would never be able to accede to Nature, to admit we aren't stronger than natural forces. Because of course even though our actions have triggered it, the results of global warming are natural, forces of Nature. And Nature will beat us, physical reality will beat us, unless we learn that we have to live as part of Nature and not act like we are separate and above it. But sadly, even Katrina has not taught us this lesson.

It's very depressing indeed. I think, though, that soon we won't be able to delude ourselves any longer.

If we suspect that the computer models for global warming are flawed, why are we so arrogant to think that they are only flawed in a manner that underestimates the effects of global warming?

With these effects (sea ice and permafrost melting) occuring much more quickly than anticipated, do you really believe it is arrogance to suspect models are underestimating future effects?

I have noticed (despite what reports, time lines and graphs show), dangerous and/or consequential natural and human made occurances are becoming worse and more frequent, theres no doubt in my mind. I've heard many people say, 'oh, not in my lifetime', but thats just bull. It's your lifetime now and it is happening now. If you're just not completely informed (which is true in many cases), thats one thing but to deny it when you plainly know is being in denial. It's simple to understand that things like this will only get worse with time, it's inevitable. We are only pushing the natural course of life and nature more quickly along.

With these effects (sea ice and permafrost melting) occuring much more quickly than anticipated, do you really believe it is arrogance to suspect models are underestimating future effects?

The rate of temperature change can act in one of three ways:


The rate of temperature change will remain the same.
The rate of temperature change will rise.
The rate of temperature change will fall.


Over a period of time, the rate of temperature change can change by shifting from one possibility to another. For example, the rate of temperature change could quickly rise, then later fall.

Assuming that the rate of temperature change will rise over the next 100 years is an opinion, not a fact. If it was that simple, we wouldn't have all these debates on climate change. :)

Scientific theories are not exactly in the same category as "opinions." Scientific theories are not "facts" it is true - facts can only be observed as they occur. However, we would be in a sad state, without science altogether, if we shrugged and said "scientific theory is only an opinion."

Nobody said any of this is simple! Don't set up some kind of dopey strawman like that, it makes no sense.

I get so frustrated by this nonsense.