Monday, September 6, 2010
Clear Sailing Across Antarctica
This is of great interest. It is an additional confirmation that the global temperature rose sharply some 125,000 years ago. This strongly suggests that the actual orbit through the Sirius Cluster is that time period plus an additional 40 to 60,000 years or approaching an orbital period of 185,000 years. This wonderfully matches the time periods proposed by the proponents of alternate history such as Sitchen. The details might be muddy but the claimed time periods are another matter altogether.
The reality is that the Antarctic Ice Cores and other work disclose that at we have had four recognized passes in the ice record. Thus the cores actually describe a 750 million year history, or twice our present interpretation. This is because a lot of the ice was lost through each pass and the record is foreshortened by at least half.
Integrating all this with sea bed cores will need to be attempted. It is plausible that we have introduced the error back into interpretation of those cores.
There is a seaway buried under the ice that is well understood and it separates
Antarctica into two major continental land masses. The closeness of the two groups of organisms is predictable if a recent opening has taken place. I do not think it works as well for millions of years.
I doubt if the waterway was ever truly sailable.
TUESDAY, AUGUST 31, 2010 AT 18:55
Why are two groups of tiny sea creatures called bryozoans nearly identical, despite being separated by 1,500 miles of ice? They must have traveled across the continent long ago - on a massive Antarctic seaway.
The bryozoan is a simple marine organism that attaches itself to the sea bed and filters nutrients out of the surrounding water. There are many different bryozoan sub-species, but a new survey of Antarctic organisms turned up some striking similarities between two distant populations. Both live on continental ice shelves, massively thick ice platforms that are created when continental glaciers reach the sea. One population is on the
Ross Ice Shelf, and the other is on the Weddell Ice Shelf. As you can see on this map, there's a whole lot of Antarctica between those two populations. So how did such similar species get to such distant locations?
David Barnes, a scientist with the British Antarctic Survey, explains why the animals couldn't have simply worked their way around the Antarctic coastline, and why they must have traveled through the continent:
"When we found groups of strikingly similar bryozoans hundreds of miles apart we knew we were onto something very interesting. Perhaps these species had survived the last ice age whereas in all other regions of
Antarctica they were wiped out. We know that after the last ice age groups of bryozoans dispersed freely between many of the regions we studied. But because the larvae of these animals sink and this stage of their life is short – and the adult form anchors itself to the seabed – it's very unlikely that they would have dispersed the long distances carried by ocean currents. For the bryozoans on both the Weddell and Ross sea continental shelves to be more similar to one another than to any of those found in the waters in between is striking indeed. Our conclusion is that the colonization of both these regions is a signal that both seas were connected by a trans-Antarctic seaway in the recent past."
This seaway could have opened up as recently as 125,000 years ago, during an interglacial warm period in which the sea levels were about fifteen feet higher than they are now. We don't know the exact processes that caused this seaway to open up, but they created an opening through what's now over a mile of solid ice. The ancient seaway also calls into question how stable
Antarctica's ice is today.
The West Antarctic Ice Sheet, which is the region through which this trans-Antarctic seaway must have traveled, is thought to be unstable and in danger of collapsing, partially as a result of climate change. If the ice sheet does collapse, it could increase global sea levels by 10 to 15 feet, which could displace billions of people from their homes. The bryozoan discovery could, however, help us better understand how a melting
Antarctica fits into current climate change. Barnes explains:
"The West Antarctic Ice Sheet can be considered the Achilles heel of
Antarctica and because any collapse will have implications for future sea level rise it's important that scientists get a better understanding of big deglaciation events. This biological evidence is one of the novel ways that we look for clues that help us reconstruct Antarctica's ice sheet history. Our new research provides compelling evidence that a seaway stretching across West Antarctica could have opened up only if the ice sheet had collapsed in the past."