Cidersomerset
1st August 2013, 22:32
I was watching Graham Hancocks interview with Lilou earlier and
in the second part he was discussing some of this.
http://static.bbci.co.uk/frameworks/barlesque/2.48.3/desktop/3.5/img/blq-blocks_grey_alpha.png
1 August 2013 Last updated at 19:52
Ice core data supports ancient space impact ideaBy Simon Redfern
Reporter, BBC News
Greenland ice core Greenland ice cores provide a window into the past
http://news.bbcimg.co.uk/media/images/69073000/jpg/_69073068_69072747.jpg
New data from Greenland ice cores suggest North America may have suffered a
large cosmic impact about 12,900 years ago.
A layer of platinum is seen in ice of the same age as a known abrupt climate
transition, US scientists report.The climate flip has previously been linked to the
demise of the North American "Clovis" people.The data seem to back the idea that
an impact tipped the climate into a colder phase, a point of current debate.
Rapid climate change occurred 12,900 years ago, and it is proposed that this is
associated with the extinction of large mammals such as the mammoth, widespread
wildfires, and rapid changes in atmospheric and ocean circulation. All of these have
previously been linked to a cosmic impact, but the theory has been hotly disputed
due to lack of clear evidence.
New platinum measurements were made on ice cores that allow conditions 13,000
years ago to be determined at a time resolution of better than five years, report
Michail Petaev and colleagues from Harvard University. Their results are published
in the journal Proceedings of the National Academy of Sciences.
A 100-fold spike in platinum concentration occurs in ice that is around 12,890 years
old, at just the same moment that rapid cooling of the climate is indicated from
oxygen isotope measurements, at the start of a climatic period called the "Younger
Dryas".
The Younger Dryas started and finished abruptly, and is one of a number of shorter
periods of climate change that appear to have occurred since the last glacial
maximum of 20,000 years ago.
Each end of the Younger Dryas period may have involved very rapid changes in
temperature as the climate system reached a tipping point, with suggestions that
dramatic changes in temperature occurred over as short as timescale as a decade
or so.
Asteroid apocalypse?
The observations lend credence to earlier, disputed, reports that finds of
microscopic grains of diamond and a mineral called lonsdaleite in lake sediments
dated to the same time were identified with a possible meteorite impact. Those
measurements resemble the most recent observations of remnants of the Tunguska
meteorite impact in Siberia, reported last month.
Sphere-shaped particles have also been identified at many localities in sediments
dating to this event, most recently reported this month by a team led from Canada
in the Journal of Geology. Such particles are characteristic of the rapidly heated and
cooled splatter of material thrown up when meteorites hit Earth.
http://news.bbcimg.co.uk/media/images/48930000/jpg/_48930535_48930536.jpg
Artist's impression of mammoths (BBC) North American mystery: At least 17
groups of large animals died out in a very short space of time
While the platinum data and the spherical particles add to evidence for an impact
event, doubters have pointed out that, as yet, no impact site has been identified.
It has been suggested that debris thrown into the atmosphere in an impact tipped
the Earth into global cooling at a rate as rapid as the global changes in climate in
the reverse direction seen in the last century. Such rapid climate change makes it
difficult for ecologies and societies to adjust: It is the fluctuation that has been
invoked as the cause of the extinction of massive mammals (megafauna) like the
mammoth, and native cultures such as the Clovis people in North America.
The possible role of cosmic impacts in causing huge changes to life on Earth is
receiving increased attention. The mass extinction 66 million years ago that wiped
out the dinosaurs is generally believed to be linked to a space strike in southern
Mexico's Yucatan Peninsula.
Recently, a group of scientists led by Eric Tohver at the University of Western
Australia reported that the biggest extinction of all, which occurred 252.3 million
years ago at the end of the Permian period, could be explained by an asteroid
impact in Brazil.
Nasa is now focusing resources towards detection of future Earth-threatening
asteroids, receiving over 400 responses to their recent request for ideas to feed
into their Asteroid Grand Challenge, in which they hope to redirect a space rock and
send humans to study it.
http://www.bbc.co.uk/news/science-environment-23536567
in the second part he was discussing some of this.
http://static.bbci.co.uk/frameworks/barlesque/2.48.3/desktop/3.5/img/blq-blocks_grey_alpha.png
1 August 2013 Last updated at 19:52
Ice core data supports ancient space impact ideaBy Simon Redfern
Reporter, BBC News
Greenland ice core Greenland ice cores provide a window into the past
http://news.bbcimg.co.uk/media/images/69073000/jpg/_69073068_69072747.jpg
New data from Greenland ice cores suggest North America may have suffered a
large cosmic impact about 12,900 years ago.
A layer of platinum is seen in ice of the same age as a known abrupt climate
transition, US scientists report.The climate flip has previously been linked to the
demise of the North American "Clovis" people.The data seem to back the idea that
an impact tipped the climate into a colder phase, a point of current debate.
Rapid climate change occurred 12,900 years ago, and it is proposed that this is
associated with the extinction of large mammals such as the mammoth, widespread
wildfires, and rapid changes in atmospheric and ocean circulation. All of these have
previously been linked to a cosmic impact, but the theory has been hotly disputed
due to lack of clear evidence.
New platinum measurements were made on ice cores that allow conditions 13,000
years ago to be determined at a time resolution of better than five years, report
Michail Petaev and colleagues from Harvard University. Their results are published
in the journal Proceedings of the National Academy of Sciences.
A 100-fold spike in platinum concentration occurs in ice that is around 12,890 years
old, at just the same moment that rapid cooling of the climate is indicated from
oxygen isotope measurements, at the start of a climatic period called the "Younger
Dryas".
The Younger Dryas started and finished abruptly, and is one of a number of shorter
periods of climate change that appear to have occurred since the last glacial
maximum of 20,000 years ago.
Each end of the Younger Dryas period may have involved very rapid changes in
temperature as the climate system reached a tipping point, with suggestions that
dramatic changes in temperature occurred over as short as timescale as a decade
or so.
Asteroid apocalypse?
The observations lend credence to earlier, disputed, reports that finds of
microscopic grains of diamond and a mineral called lonsdaleite in lake sediments
dated to the same time were identified with a possible meteorite impact. Those
measurements resemble the most recent observations of remnants of the Tunguska
meteorite impact in Siberia, reported last month.
Sphere-shaped particles have also been identified at many localities in sediments
dating to this event, most recently reported this month by a team led from Canada
in the Journal of Geology. Such particles are characteristic of the rapidly heated and
cooled splatter of material thrown up when meteorites hit Earth.
http://news.bbcimg.co.uk/media/images/48930000/jpg/_48930535_48930536.jpg
Artist's impression of mammoths (BBC) North American mystery: At least 17
groups of large animals died out in a very short space of time
While the platinum data and the spherical particles add to evidence for an impact
event, doubters have pointed out that, as yet, no impact site has been identified.
It has been suggested that debris thrown into the atmosphere in an impact tipped
the Earth into global cooling at a rate as rapid as the global changes in climate in
the reverse direction seen in the last century. Such rapid climate change makes it
difficult for ecologies and societies to adjust: It is the fluctuation that has been
invoked as the cause of the extinction of massive mammals (megafauna) like the
mammoth, and native cultures such as the Clovis people in North America.
The possible role of cosmic impacts in causing huge changes to life on Earth is
receiving increased attention. The mass extinction 66 million years ago that wiped
out the dinosaurs is generally believed to be linked to a space strike in southern
Mexico's Yucatan Peninsula.
Recently, a group of scientists led by Eric Tohver at the University of Western
Australia reported that the biggest extinction of all, which occurred 252.3 million
years ago at the end of the Permian period, could be explained by an asteroid
impact in Brazil.
Nasa is now focusing resources towards detection of future Earth-threatening
asteroids, receiving over 400 responses to their recent request for ideas to feed
into their Asteroid Grand Challenge, in which they hope to redirect a space rock and
send humans to study it.
http://www.bbc.co.uk/news/science-environment-23536567