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Allen McDonnell
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Werther I am with Sam on this one, I think the cell structure of the northern hemisphere is becoming unstable, and I don't believe even numbered structures are stable for extended periods of time. The sooner you can get back to us on the summer data the better I will like it ;) though I hope I am wrong of course.
Congrats Neven, let me just add to the chorus and say, cutting off the people who argue for the sake of their own doubts is a good thing. Anyone who wants to learn is gifted a great deal of information on the Internet as a whole. This blog has some of the best critical thinking applied to that information expressed in a way that anyone of average intelligence can easily understand.
Like Robert said above, I have seen that very thing happen on Lake Erie many times when I was younger. The last few years it hasn't frozen hard enough to cover the whole surface so the ice degrades from the open edge. In the years past it woul look fine one day and crack into ice flows.
@Ned While there re strong proxies for higher peak temperatures in the past there is a second indicator whis is often inored. Duration. The last interglacial before the current on for example was warmer than the Holocene, however it was quite short. The Holocene has already lasted over twice as long as the Eemian did 125,000 years ago. Less time means less total mpact, like baking a loaf of bread at 350 for 20 min instead of 340 for 40 min. You just can't get the same results that way.
Toggle Commented Aug 5, 2013 on Arctic time bombs at Arctic Sea Ice
@Bosbas Based on the lecture series by Dr. David Archer and his book The Long Thaw the CO2 will drop off by 50% over three centuries. That is half the slug added by humanity, but after that the ocean is saturated to equalibrium with the atmosphere. To drop from 400 half way to 280 only gets you down to 340, but in essence if we could stop adding today we would stop making it worse. Even better the drop would be steeper at the beginning and slow down as h 300 years went by. However we all know humanity isn't going to stop releasing CO2 tomorrow or in all likelyhood any time before fossil fuels run out.
Toggle Commented Aug 1, 2013 on Second storm at Arctic Sea Ice
I think a big part of the uncertainty is that we are approaching or very close to a tipping point, so the climate is entering a period of instability. If we push the climate hard enough we will pass through the tipping point and settle into a new quasi stable regime, or if we quickly stop using fossil fuels we will back away from the tipping point and things will return to say 1950 regimes. This makes predicting weather almost impossible on a year by year basis because any two years can be divergent. That doesn't mean we shouldn't try and figure things out, but I believe the uncertainty will remain very high until we either stop perturbing the system or flip it into a different state. Climate changes in the geological record are always presumed to be caused by long slow processes, but even in the long slow change pattern the actual step change from one state to the next is fairly abrupt. Most epochs are defined by an extinction event that makes geological dating of the strata distinct from the prior layer. Because most extinction events took some time to effect the entire species there is uncertainty about he exact dates, the key species may have persisted for thousands of years in some favorable climate spot after it died out everywhere else for example. Over geological time scales the climate uncertainty effect would be a gradual shift from one state to the next and the unsettled period would be spread out over many generations, but the human CO2 impact is incredibly fast. Current CO2 levels would be normal for a northern hemisphere in the single cell configuration, but in the course of a natural change it would take thousands of years to increase as much as we have done in 250. Between 20,000 ybp and 12,000 ybp CO2 increased from around 180 ppm to 275 ppm. Over those 8,000 years 2/3rds of the ice sheets on the whole planet melted. From 1760 to 2010 humans changed the CO2 from 275 ppm to 395 yearly averages. The system has not had time to react to this very rapid change, especially considering he rate of change has been going up the whole time. If the change had occurred over a geologically rapid 8,000 years as it did at the end of the last major glaciation there probably wouldn't be much ice left in Greenland by now and the climate patterns wouldn't be so chaotic as the tipping point approaches. The way things stand now the CO2 forcing is in strong conflict with the albedo forcing, if the change had taken thousands of years the albedo would have smoothly decreased as the CO2 forcing increased.
Toggle Commented Jul 31, 2013 on Second storm at Arctic Sea Ice
My statement about the arctic shelf methane releasing being nothing but a blip appears to have not been clear in context. What I mean is, releasing the arctic shelf methane will not have a long enough duration sustained warming effect to warm deeper waters and release the bulk of methane clathrates. So long as the vast deep and intermediate ocean stay cold enough those clathrates will stay stable. It is not great news that the shelf clathrates could be breaking down, but it isn't doom to the 12th order either.
Toggle Commented Jul 31, 2013 on Arctic time bombs at Arctic Sea Ice
In the millennial length future we need to member isostatic rebound, a lot of the center of Greenland that is currently below sea level is depressed by the weight of the ice. Take away the ice and the whole center will spring up just like Canada around Hudson's bay did 12000 years ago and is still doing at a slow rate. It is debatable if our distant descendants will find Greenland to be an atoll surrounding a lake or if it will be a flat plain ringed by high mountains. Yes I believe it will all melt.
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Jul 31, 2013