The Arctic

Tim Helweg-Larsen & Richard Hawkins

1989

2007

1989 2007

Arctic Sea Ice Extent Area 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 already too 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?

energy

So what?

Over and above existing model projections

1989 2012?

Albedo %

of

radi

atio

n re

flec

ted

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

1672 billion 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

What does this mean?

2°

next?

What

end the

Tim Helweg-Larsen & Richard Hawkins