What was the singular thing that made you personally change an AI research career into doing research and later advocacy on ending aging?
Frozen Viking farms and de-iced polar bears
on
Global Warming Debunked?
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· Score: 2, Interesting
Hi,
I browsed through the article. A couple of things I would like to see better backed up by scientific references.
ISSUE 1: Viking farms
Article: "There were Viking farms in Greenland: now they're under permafrost. "
"Reference" linked from article: "Greenland in the Middle Ages: Eric the Red had named Greenland "Greenland" to encourage Danish settlers, because in his time south-western Greenland was indeed green. It was ice-free, and was extensively cultivated until c.1425 AD, when the farms were suddenly overrun by permafrost. The Viking agricultural settlements remain under permafrost to this day - a powerful indication that the Middle Ages were warmer than the present, and that there is little cause for alarm at the current melting of Greenland glaciers because they are very likely to have melted to more than their present extent during the mediaeval warm period."
A related article I found on the web: http://www.expressnews.ualberta.ca/article.cfm?id= 776 According to this, the farms are indeed under permafrost. However, it seems the reason for failure of the farms was not frost, but sand blown over the farms. Which is naturally caused by runaway erosion, which I had understood the Vikings had caused themselves by chopping down everything resembling trees (as happened with Iceland). If there were forests before, losing them would also mean changing the local microclimates, exposing the farms to chilly winds, and thus triggering the local freezing?
So to me it is not certain that global temperature change caused the freezing or non-freezing of the farmed areas. Somebody got harder facts?
ISSUE 2: Polar bears and iceless Arctic
Article: "There was little ice at the North Pole: a Chinese naval squadron sailed right round the Arctic in 1421 and found none."
Reference linked from article: "In 1421 a Chinese Imperial Navy squadron sailed right round the Arctic and found no ice anywhere. It is possible that at that time there was less of an icecap at the North Pole than there is now, particularly in summer. Yet the polar bears survived. Though there has been much discussion of the supposed threat posed by the warmer Arctic, the polar bears are thriving in the current warm period. Eleven of the thirteen principal known families are prospering as never before."
What does it mean "thriving as never before?" The Polar Bear Specialist Group has a table of the population status of 20 polar bear populations (http://pbsg.npolar.no/status-table.htm). Two populations are decreasing in numbers, and *additionally* "thinner bears, lower female reproductive rates, and reduced juvenile survival in the Western Hudson Bay polar bear population in Canada, which is at the southern edge of the species' range and the first to suffer impacts from global warming."
Most of the populations are tagged "W - evidence global warming effects on sea ice or populations"
The populations do not change in a few years time. "Polar bears rely almost entirely on the marine sea ice environment for their survival so that large scale changes in their habitat will impact the population (Derocher et al. 2004). Global climate change posses a substantial threat to the habitat of polar bears. Recent modeling of the trends for sea ice extent, thickness and timing of coverage predicts dramatic reductions in sea ice coverage over the next 50-100 years (Hassol 2004)." http://www.iucnredlist.org/search/details.php/2282 3/all
I would be extremely surprised about the adaptivity of polar bears had they survived without polar sea ice during hundreds of years during the assumed iceless period, and then within hundreds of years fully retaken
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What was the singular thing that made you personally change an AI research career into doing research and later advocacy on ending aging?
Hi,
I browsed through the article. A couple of things I would like to see better backed up by scientific references.
ISSUE 1: Viking farms
Article: "There were Viking farms in Greenland: now they're under permafrost. "
"Reference" linked from article: "Greenland in the Middle Ages: Eric the Red had named Greenland "Greenland" to encourage Danish
settlers, because in his time south-western Greenland was indeed green. It was ice-free, and was extensively cultivated until c.1425 AD, when the farms were suddenly overrun by permafrost. The Viking agricultural settlements remain under permafrost to this day - a powerful indication that the Middle Ages were warmer than the present, and that there is little cause for alarm at the current melting of Greenland glaciers because they are very likely to have melted to more than their present extent during the mediaeval warm period."
Permafrost or not, it seems that some vegetation does thrive in Greenland summer: http://www.narsaq.dk/green-00.html
A related article I found on the web: http://www.expressnews.ualberta.ca/article.cfm?id= 776
According to this, the farms are indeed under permafrost. However, it seems the reason for failure of the farms was not frost, but sand blown over the farms. Which is naturally caused by runaway erosion, which I had understood the Vikings had caused themselves by chopping down everything resembling trees (as happened with Iceland). If there were forests before, losing them would also mean changing the local microclimates, exposing the farms to chilly winds, and thus triggering the local freezing?
So to me it is not certain that global temperature change caused the freezing or non-freezing of the farmed areas. Somebody got harder facts?
ISSUE 2: Polar bears and iceless Arctic
Article: "There was little ice at the North Pole: a Chinese naval squadron sailed right round the Arctic in 1421 and found none."
Reference linked from article: "In 1421 a Chinese Imperial Navy squadron sailed right round the Arctic and found no ice anywhere. It is possible that at that time there was less of an icecap at the North Pole than there is now, particularly in summer. Yet the polar bears survived. Though there has been much discussion of the supposed threat posed by the warmer Arctic, the polar bears are thriving in the current warm period. Eleven of the thirteen principal known families are prospering as never before."
What does it mean "thriving as never before?" The Polar Bear Specialist Group has a table of the population status of 20 polar bear populations (http://pbsg.npolar.no/status-table.htm). Two populations are decreasing in numbers, and *additionally* "thinner bears, lower female reproductive rates, and reduced juvenile survival in the Western Hudson Bay polar bear population in Canada, which is at the southern edge of the species' range and the first to suffer impacts from global warming."
Most of the populations are tagged "W - evidence global warming effects on sea ice or populations"
The populations do not change in a few years time. "Polar bears rely almost entirely on the marine sea ice environment for their survival so that large scale changes in their habitat will impact the population (Derocher et al. 2004). Global climate change posses a substantial threat to the habitat of polar bears. Recent modeling of the trends for sea ice extent, thickness and timing of coverage predicts dramatic reductions in sea ice coverage over the next 50-100 years (Hassol 2004)." http://www.iucnredlist.org/search/details.php/2282 3/all
I would be extremely surprised about the adaptivity of polar bears had they survived without polar sea ice during hundreds of years during the assumed iceless period, and then within hundreds of years fully retaken