Part one of a two part talk describing a remarkable event that occurred in the Arctic 50 million years ago, when a unique floating freshwater plant called Azolla repeatedly covered the surface of the ocean for almost a million years. Due to its phenomenal growth, Azolla sequestered enormous quantities of the greenhouse gas carbon dioxide, and changed the Earth's climate from a greenhouse world towards our modern icehouse climate with its permanent ice and snow at both poles. 'The Arctic Azolla Event' was discovered by the Arctic Coring Expedition (ACEX) when it recovered sediments beneath the North Pole in 2004. The discovery was featured in the New York Times (November 20, 2004) and National Geographic (May 2005), and its validity has now been confirmed by international teams of scientists who have investigated and published on the cores, including a series of papers in the scientific journal ‘Nature’.
12. we think of our climate as being normal
but it is very rare
and we last see this in the early Eocene just over 50 million years ago
13. we know of no previous time when our planet had bipolar glaciation
and we last see this in the early Eocene just over 50 million years ago
14. for most of its history our planet had a greenhouse climate
a world with warm temperatures from pole to pole
and we last see this in the early Eocene just over 50 million years ago
15. we last saw this in the early Eocene just over 50 million years ago
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16. lush forests grew on Ellesmere Island just a few hundred kilometres
from the North Pole where temperatures rarely climb above freezing today
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pole
Ellesmere
17. icehouse
and then, 50 million years ago the climate
abruptly shifted towards an icehouse state
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18. icehouse
to understand why we need to first look
at the land – sea configuration at the poles
which results from plate tectonics
51. • CO2 determined from
boron 11 isotope in forams
• isotope changes reflect shifts in
surface water acidity and
atmospheric CO2
going back
to the Paleogene
63. back into the early Eocene
Sources: Trapiti et al. Nature July 2005
Pagani et al. Science July 2005
Pearson & Palmer Nature August 2000
Paleocene - early Eocene
values reach 3500 ppm
64. we see a major decrease at
the base of the Middle Eocene
from 3500ppm to 600 ppm
79. Paleocene Eocene Thermal Maximum [PETM]
supergreenhouse state triggered by increased greenhouse gases from
• extensive volcanism
• release of methane clathrates
80. this is coeval with
maximum activity
of the Greenland
Mantle Plume
86. the answer finally came in 2004
when the Integrated Ocean
Drilling Project (IODP) was
finally able to drill
in the Arctic due to
reduced ice cover…..
1979
2004
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