The Science on Polar Bears
A witness to polar bears' plight, photographer and writer Jenny Ross, shares photos and explains what recent scientific studies are finding on the effects of climate change on polar bears.
It is not often that I read something as clear and
compelling as the recent article on
polar bears in the Arctic by nature photographer Jenny Ross, whose
photographs bring to life the struggle polar bears face as the Arctic warms.
The thing about this article,
which makes it worth sitting down and losing yourself in her story and photographs, is the clear and detailed description of how
polar bears' lives are intertwined with Arctic ice. Ross explains:
Due to their compulsory connections with sea
ice for every crucial facet of life, polar bears are exceedingly vulnerable to
the effects of climate warming.
Polar bear's dependence on sea
ice is clear when you consider that their main source of food is ringed seals,
a species that itself depends on sea ice to survive. All of polar bears' methods
of catching seals depend on sea ice--they wait motionless by seals’ breathing holes in the
ice until a seal returns or slowly stalk up to a seal resting on the
sea-ice surface. Yet, as the ice disappears earler in the spring and forms later in the fall, polar bears cannot switch to other food sources because they
require tremendous amounts of energy from the high-fat seals to stay warm.
Struggles for Polar
Bears as Ice Melts
Ross has spent time observing polar bears in the wild, and
gives a first-hand account of watching individual polar bears swimming in the
open ocean hundreds of miles from the nearest sea ice--in an area of the Arctic
that only a few decades earlier were covered in ice year round. These types of long swims are becoming more
common as the ice retreats, yet can be deadly for polar bears and their cubs.
In addition to overly-long swims to find retreating sea ice, ice-free periods in the summer are becoming longer in southern areas of their range.
Research by Stirling and colleagues
has established that during the past few decades, due to climate warming, the
sea ice on Hudson Bay has been breaking up progressively earlier in the summer.
Break-up now occurs at least four weeks earlier than it did a few decades ago.
Consequently, the WHB [Western Hudson Bay] bears have much less time on the ice
to hunt seals and accumulate the fat necessary to survive the ice-free period.
Furthermore, explains Stirling, in addition to coming ashore with meager
quantities of stored fat, "the bears are now being forced to fast for even
longer periods because freeze-up is coming progressively later in the fall as
Read more on how polar bears'
lives are changing in the southern areas of the Arctic--and what the science is
telling us about their future.
Research on the
Future of Polar Bears
Right now, there are approximately 20,000 polar bears living
in 19 relatively separate populations, but scientists determined that 8 of the
19 populations are already declining due to global warming. If temperatures continue to
rise unchecked, scientists expect at least two-thirds of the world's polar
bears will disappear within the next 40 years. But, all is not lost for polar bears living
further north in the Arctic. Polar bear researcher Dr. Ian Amstrup explains:
"There's a widely held
perception that nothing can be done to help polar bears and the arctic
ecosystem," says Amstrup. "Our new findings show this isn't true.
Saving polar bears is all about temperature and sea ice. By minimizing
greenhouse-gas emissions and therefore temperature rise, we will retain more
sea ice. The more sea-ice habitat we retain, the more polar bears will
Join the fight for the future of polar bears--donate to the National Wildlife Federation Action Fund to continue the campaign in 2012 to limit global warming pollution.