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Tim Helweg-Larsen & Richard Hawkins
The Arctic
1989
2007
1989 2007
Arctic Sea Ice ExtentArea of ocean with at least 15% sea ice
1989
2007
1989 / 2007
+ 5 years − 5 years Ocean
Age of Arctic Sea Ice
IPCC, WG I (2007)
… late summer sea-ice is projected to
disappear almost completely towards the end of the 21st century
“The Arctic Ocean could be nearly ice-free at the end of summer by 2012”
Dr Jay Zwally, NASA
“Our projection of 2013 is alreadytoo conservative.”
Dr Wieslaw Maslowski, US Navy
“Worst-case scenarios about sea-ice loss are coming true: the Arctic Ocean could be ice-
free in summertime as soon as 2010”
Louis Fortier, Université Laval
Mark Serreze, NSIDC
No matter where we stand at the end of the
melt season, it’s just reinforcing this notion that the Arctic ice is in
its death spiral.
So what?
Over and above existing model projections
1989 2012?
Albedo%
of
rad
iati
on
refl
ecte
d
Hugo Ahlenius,UNEP/GRID-Arendal
≈
0.3°C
Permafrost extent in the Northern Hemisphere, http://maps.grida.no/go/graphic/permafrost-extent-in-the-northern-hemisphere
1672billion
tonnes
0.1% melt = 1600mtc
80% global cut
=1600mtc
Existing coupled climate models lack a
robust treatment of soil carbon dynamics.
The [IPCC] range does not include
… contributions from rapid dynamic processes in the
Greenland and West Antarctic ice sheets which… could
eventually raise sea level by many meters. Lacking such
processes… projections based on such models may seriously
understate potential future increases.
Oppenheimer et al.
IPCC, Synthesis (2007)
“Because understanding of some important effects driving
sea-level rise is too limited, this report does not assess the
likelihood, nor provide a best estimate or an upper bound for
sea-level rise… therefore the upper values of the ranges are
not to be considered upper bounds for sea-level rise.”
Over and above existing model projections
Additional
endthe
Tim Helweg-Larsen & Richard Hawkins
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