Sorry, i haven’t but I will when the Breakthrough conference is over in two weeks.
Interesting what the research published in May found was very similar to the story we told in Climate Code Red in 2008 in Chapter 3:
Trouble in the Antarctic
Big changes are also underway at the other end of the world,
in the Antarctic, where most of the world’s ice sits on the fi fthlargest
continent. The majority of Antarctic ice is contained in
the East Antarctic ice sheet — the biggest slab of ice on Earth,
which has been in place for some 20 million years and which,
if fully melted, would raise sea levels by more than 60 metres.
Considered more vulnerable is the smaller West Antarctic
ice sheet, which contains one-tenth of the total Antarctic ice
volume. If it disintegrated, it would raise sea levels by around
5 metres, a similar amount to what we would see with a total
loss of the Greenland ice sheet.
While it was generally anticipated that the West Antarctic
sheet would be more stable than Greenland at a 1–2 degree
rise, recent research demonstrates that the southern ice shelf
reacts far more sensitively to warming temperatures than
scientists had previously believed. Ice-core data from the
Antarctic Geological Drilling joint project (being conducted
by Germany, Italy, New Zealand, and the United States) shows
that ‘massive melting’ must have occurred in the Antarctic
three million years ago, during the Miocene–Pliocene period,
when the average global temperature in the oceans increased
by only 2–3 degrees above the present temperature. Geologist
Lothar Viereck-Götte called the results ‘horrifying’, and
suggested that ‘the ice caps are substantially more mobile and
sensitive than we had assumed’.
The heating effect caused by climate change is greatest
at the poles, and the air over the West Antarctic peninsula
has warmed nearly 6 degrees since 1950. At the same time,
according to a report in the Washington Post on 22 October
2007, a warming sea is melting the ice-cap edges, and beech
trees and grass are taking root on the ice fringes.
Another warning sign was the rapid collapse in March 2002
of the 200-metre-thick Larsen B ice shelf, which had been stable
for at least twelve thousand years, and which was the main
outlet for glaciers draining from West Antarctica. An ice shelf
is a fl oating sheet, or platform, of ice. Largely submerged, and
up to a kilometre thick, the shelf abuts the land and is formed
when glaciers or land-based ice fl ows into the sea. Generally,
an ice shelf will lose volume by calving icebergs, but these are
also subject to rapid disintegration events. Larsen B, weakened
by water-fi lled cracks where its shelf attached to the Antarctic
Peninsula, gave way in a matter of days, releasing fi ve hundred
billion tonnes of ice into the ocean.
Neil Glasser of Aberystwyth University and Ted Scambos
from the NSIDC found that as glacier fl ow had begun to
increase during the 1990s, the ice shelf had become stressed.
The warming of deep Southern Ocean currents (which
increasingly reach the Antarctic coastline) had also led to
some thinning of the shelf, making it more prone to breaking
apart. Scambos concludes that ‘the unusually warm summer
of 2002, part of a multi-decade trend of warming [that is]
clearly tied to climate change, was the fi nal straw’.
Looking at the overall pace of events, Scambos says: ‘We
thought the southern hemisphere climate is inherently more
stable, [but] all of the time scales seem to be shortened now.
These things can happen fairly quickly. A decade or two of
warming is all you need to really change the mass balance …
Things are on more of a hair trigger than we thought.’
Much of the West Antarctic ice sheet sits on bedrock that
is below sea level, buttressed on two sides by mountains, but
held in place on the other two sides by the Ronne and Ross
ice shelves; so, if the ice shelves that buttress the ice sheet
disintegrate, sea water breeching the base of the ice sheet will
hasten the rate of disintegration.
In 1968, the Ohio State University glaciologist John Mercer
warned, in the journal of the International Association of
Scientifi c Hydrology, that the collapse of ice shelves along
the Antarctic Peninsula could herald the loss of the ice sheet
in West Antarctica. A decade later, in 1978, his views received
a wider audience in Nature, where he wrote: ‘I contend that a
major disaster — a rapid deglaciation of West Antarctica — may
be in progress … within about 50 years.’ Mercer said that
warming ‘above a critical level would remove all ice shelves, and
consequently all ice grounded below sea level, resulting in the
deglaciation of most of West Antarctica’. Such disintegration,
once under way, would ‘probably be rapid, perhaps
catastrophically so’, with most of the ice sheet lost in a century.
Credited with coining the phrase ‘the greenhouse effect’ in the
early 1960s, Mercer’s Antarctic prognosis was widely ignored
and disparaged at the time, but this has changed.
( James Hansen says it was not clear at the time whether
Mercer or his many critics were correct, but those who labelled
Mercer an alarmist were considered more authoritative and
better able to get funding. Hansen believes funding constraints
can inhibit scientifi c criticisms of the status quo. As he wrote
in New Scientist on 28 July 2007: ‘I believe there is pressure
on scientists to be conservative.’ Hansen is responsible for
coining the term ‘The John Mercer Effect’, meaning to play
down your fi ndings for fear of losing access to funding or of
being considered alarmist.)
Another vulnerable place on the West Antarctic ice sheet
is Pine Island Bay, where two large glaciers, Pine Island and
Thwaites, drain about 40 per cent of the ice sheet into the sea.
The glaciers are responding to rapid melting of their ice shelves
and their rate of fl ow has doubled, whilst the rate of mass loss
of ice from their catchment has now tripled. NASA glaciologist
Eric Rignot has studied the Pine Island glacier, and his work
has led climate writer Fred Pearce to conclude that ‘the glacier
is primed for runaway destruction’. Pearce also notes the work
of Terry Hughes of the University of Maine, who says that the
collapse of the Pine Island and Thwaites glaciers — already the
biggest causes of global sea-level rises — could destabilise the
whole of the West Antarctic ice sheet. Pearce is also swayed by
geologist Richard Alley, who says there is ‘a possibility that the
West Antarctic ice sheet could collapse and raise sea levels by 6
yards [5.5 metres]’, this century.
Hansen and fellow NASA Goddard Institute for Space
Studies researcher Makiko Sato agree: