Arctic sea ice loss could threaten even land animals
The melting of Arctic sea ice as the climate
warms is such a dramatic change to northern
ecosystems that it will have a serious impact
not just on ocean dwellers such as whales
and seals, but land animals such as caribou
and foxes, scientists say.
The proportion of the Arctic covered by sea
ice during the summer hit a
record low in 2012. Since 1979,
the summer sea ice coverage
has declined by about three-
million kilometres squared,
losing an area larger than the
province of New Brunswick
each year, scientific records
show. Because dark open
water reflects far less sunlight
than ice, warming accelerates
with sea ice loss, which in turn
causes the ice to melt more
quickly.
While most people see the loss
of sea ice as a sign or
indicator of climate change,
it's far more than that, say
U.S. and Canadian scientists in
a paper published Thursday
online in the journal Science.
See a lake produced by melting ice at the
North Pole
Sea ice in the Arctic is analogous to trees in
a forest, said Jedediah Brodie, a conservation
ecologist at the University of British
Columbia who co-authored the paper.
"When you cut the trees, you alter the entire
ecosystem — every other species that lives in
a forest in some way depends on those
trees," he said in a phone interview.
'Loss of a globally important
ecosystem'
The loss of sea ice is "actually the loss of a
habitat," he added, "and that's the loss of a
globally important ecosystem."
Sea ice plays a huge role in the Arctic
because 80 per cent of the low-lying tundra
is within 100 kiometres of the ocean that is
covered by ice for at least part of the year.
Melting Arctic ice could cause economic loss
of $60 trillion over 10 years, researchers
estimate
Penn State University biologist Eric Post, lead
author of the paper, wanted to examine the
relationships among Arctic organisms from
algae to whales to bears, and compile the
ways in which they might be affected by the
loss of sea ice. He sought help from experts
in the U.S. and Canada, including Brodie,
who researches how environmental change
affects ecosystems; University of Calgary
veterinary medicine researcher Susan Kutz;
and University of Alberta polar bear specialist
Ian Stirling.
It's most obvious that sea ice loss will affect
marine organisms, but some of the specific
effects are not intuitive.
For example, the loss of ice reduces the fat
content of algae that live between layers of
ice, making them less nourishing to marine
animals, the researchers noted.
The melting ice is also changing the timing
each summer of huge blooms of
phytoplankton that form the base of the
Arctic food chain, which may shorten the
season for the blooms, causing ripples all the
way up the food chain to fish, seabirds and
marine mammals such as seals and whales.
Many marine mammals such as seals also rely
on sea ice as a place to raise their young or
even just to rest after long dives in search of
fish. As the sea ice disappears, animals such
as walruses have been crowding onto
shorelines, which can lead to their young
being trampled or the spread of disease
through the population.
The loss of sea ice also has many indirect,
inintuitive effects on both marine and land
animals.
"It can have pretty dramatic effects on
climate even far inland," Brodie said.
That in turn can affect the growth of
vegetation on land, disrupting food sources
for animals such as caribou.
Indirect effects on migration,
breeding
The article notes a number of other potential
indirect effects of sea ice loss on land
animals:
Isolation and increased inbreeding among
populations of wolves and arctic foxes, which
currently use ice to travel between
populations during most of the year.
Increased interbreeding and hybridization
between grizzly bears and polar bears
because polar bears are spending more time
on land, where they come into contact with
grizzlies.
The spread of diseases that were once
restricted by sea ice barriers to a certain part
of the Arctic, such as phocine distemper
virus, which currently affects only eastern
Arctic seals.
Increased shipping in the Canadian Arctic
and the later freeze up of the ice could
affect the annual migration of the Dolphin
and Union caribou herd.
The paper noted that it is a challenge to
forsee how sea ice decline will increase
human activities such as shipping and
industrial development in the Arctic, which
could also have negative consequences for
many species.
