Record
high Arctic temperatures in 2015 having 'profound effects' on region
Latest
Noaa report reveals 2015 temperatures were in some cases 3C above
long-term average and 70% of ice pack in March was made of first-year
ice
Oliver Milman in New
York
@olliemilman
Tuesday 15 December
2015 19.36 GMT
The Arctic
experienced record air temperatures and a new low in peak ice extent
during 2015, with scientists warning that climate change is having
“profound effects” on the entire marine ecosystem and the
indigenous communities that rely upon it.
The latest National
Oceanic and Atmospheric Administration (Noaa) report card on the
state of the Arctic revealed the annual average air temperature was
1.3C (2.3F) above the long-term average – the highest since modern
records began in 1900. In some parts of the icy region, the
temperature exceeded 3C (5.4F) above the average, taken from 1981 to
2010.
This record heat has
been accompanied by diminishing ice. The Arctic Ocean reached its
peak ice cover on 25 February – a full 15 days earlier than the
long-term average and the lowest extent recorded since records began
in 1979. The minimum ice cover, which occurred on 11 September, was
the fourth smallest in area on record.
More than 50% of
Greenland’s huge ice sheet experienced melting in 2015, with 22 of
the 45 widest and fastest-flowing glaciers shrinking in comparison to
their 2014 extent.
Not only is the ice
winnowing away, it is becoming younger – Noaa’s analysis of
satellite data shows that 70% of the ice pack in March was composed
of first-year ice, with just 3% of the ice older than four years.
This means the amount of new, thinner ice has doubled since the 1980s
and is more vulnerable to melting.
The report card –
compiled by 72 scientists from 11 countries – noted sharp
variations in conditions in the northern part of the Arctic compared
to its southern portion. The melting season was 30-40 days longer
than the long-term average in the north but slightly below average in
the south, suggesting that changes to the jet stream, causing colder
air to whip across the southern part of the Arctic, are having an
impact.
Noaa said warming in
the Arctic is occurring at twice the rate of anywhere else in the
world – a 2.9C (5.2F) average increase over the past century –
and that it is certain climate change, driven by the release of
greenhouse gases, is the cause.
“There is a close
association between air temperature and the amount of sea ice we see,
so if we reduce the temperature globally it looks like it will
stabilize the Arctic,” said Dr James Overland, oceanographer at
Noaa.
“The next
generation may see an ice-free summer but hopefully their decedents
will see more ice layering later on in the century.”
Overland said if the
world hits the 2C (3.6F) warming limit agreed by nations in the
recent Paris climate talks, the Arctic will experience a 4C (7.2F) to
5C (9F) increase in temperature by 2050. The Chukchi Sea, by Alaska,
is warming the fastest of any of the Arctic waters while the overall
minimum ice extent has slumped by 13.4% a decade, on average.
The changes in the
Arctic are also causing “major challenges” for the indigenous
communities in the region, according to Rick Spinrad, Noaa’s chief
scientist. Warmer-water fish such as cod are moving north, displacing
Arctic species, while an increase in sunlight reaching the upper
layers of the ocean triggered widespread blooms of algae in the
Bering Sea, between Alaska and Russia, in 2015.
This altered
environment is causing severe problems for walruses, with
unprecedented “haul outs” of the animals occurring in 2015. The
large marine mammals traditionally use sea ice for mating and
nurturing young but in recent years have been forced to congregate on
land in north-west Alaska. This behaviour has led to stampedes that
have killed calves and hampered walruses’ ability to find food.
“Females now have
to make 110-mile (177km) treks for food. We just haven’t seen haul
outs in these numbers before,” said Kit Kovacs, biodiversity
research program leader at the Norwegian Polar Institute. “I don’t
think there is much uncertainty here. We have a dramatic situation in
the north Pacific with walruses.”
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