Download Cool Bears + Warm Waters = Extinction?

Cool Bears + Warm Waters = Extinction?
By Karen Bunavage
One of the most fascinating creatures on this planet is the polar bear. Found only
in the northern hemisphere, polar bears live on the expansive Arctic sea ice and primarily
feed on seals. The bears have two layers of fur in addition to a fat layer that insulates
them from brutally cold Arctic temperatures, which can drop below -45º C. Polar bears
weigh up to 1,800 pounds and exceed lengths of 9 feet. Because of their size and power,
polar bears have only one main predator: humans. In recent years, however, these
creatures have been faced with the even greater threat of climate change.
Climate change generally refers to Earth’s increasing average surface
temperature. According to the National Oceanic and Atmospheric Administration’s
(NOAA) National Climatic Data Center website, average global surface temperatures
have increased by about 0.74°C since the late-19th century, with the most significant
warming occurring over the last 100 years; in fact, the ten warmest years on record have
all occurred since 1995. Increasing global temperatures are enhanced by the greenhouse
effect, which is a natural process that occurs on Earth. It is caused by the absorption of
heat by certain gases in the atmosphere called greenhouse gases and the radiation of some
of that heat back down toward the surface. Water vapor is the most important greenhouse
gas, followed by carbon dioxide and some others of less importance. The greenhouse
effect naturally heats Earth approximately 33°C; without it, the average temperature
would be about -18°C. However, over the past few hundred years, human activities, such
as the burning of fossil fuels and deforestation, have been increasing the concentration of
greenhouse gases in the atmosphere. Most of the increase is in carbon dioxide, which is
emitted into the troposphere by the burning of oil, coal, and natural gases.
In 1958, scientist Charles Keeling began taking measurements of carbon dioxide
in the atmosphere from the Mauna Loa Observatory, which is located atop Earth’s largest
volcano in Hawaii, far from humans and plants that could skew his observations. His
resulting graph, shown in Figure 1, is known today as the Keeling Curve; it confirms the
steady rise of carbon dioxide levels in the atmosphere over a 48-year period through
2005.
The regular fluxes in the graph are caused by the absorption of carbon dioxide by
plants in the spring and summer and its release in the fall and winter. Keeling’s record
was the first to confirm the rise of carbon dioxide in the troposphere as a result of burning
fossil fuels. The increase in carbon dioxide has led our planet to experience an increase in
the greenhouse effect, which is the cause of our higher temperatures and the problems
associated with them.
As Earth is heating up, so are the oceans. Over the past several decades, Arctic
temperatures rose nearly twice as much as those in the rest of the world; according to the
Canadian World Wildlife Fund, for instance, the average temperature of the Canadian
Arctic increased by about 4º C over the last 50 years. Warming in the Arctic happened
much faster than models initially suggested, and NOAA estimates that the amount of
September Arctic sea ice has been decreasing at a rate of about 10 percent per decade
since 1973. That region is experiencing the greatest amount of warming partly because of
its high albedo: the more reflective ice and snow melt, leaving darker areas of ocean and
land that absorb the sun’s energy and work to heat Earth even further. The illustration in
Figure 2 shows the increase in surface air temperatures, including ocean surface
temperatures, from 1960 to 2060; it implies that the poles are experiencing the greatest
amount of warming.
Although it is clear that global temperatures are rising, there has been much
debate over whether it is due to increased atmospheric carbon dioxide concentrations or if
it is part of a natural cycle. However, it has been determined with more than 90 percent
confidence by the Intergovernmental Panel on Climate Change that warming in the Arctic
is in fact human-induced; our activities have caused a dangerous build up of the potent
greenhouse gas in our atmosphere. Although there are some natural forces, such as
sunspots and ocean currents that may have contributed to the problem, they are only
secondary factors. Overall, we are the direct cause of the climate change crisis, and our
actions are taking a toll on the planet and all of its inhabitants.
Polar bears are one of the many species affected by melting ice caps caused by the
increase in global temperature. These animals need a platform of ice on which to live,
breed, and hunt food for sustainment. According to a Discovery News article called “Big
Question for 2012: Is the Polar Bear Doomed?” by Kieran Mulvaney, an environmental
writer, the total volume of sea ice reached a new low in 2011 for the second consecutive
year. As ice disappears, polar bears are forced to swim longer distances without food, and
they often drown. Results from a study on increased polar bear swimming distances were
presented at the International Bear Association Conference in July of 2011. Twenty bears
that were studied swam distances over 53.7 km without stopping on 50 different
occasions. In fact, the longest trip was over 687 km and took 13 days to complete. That is
a great feat, especially considering the fact that a long journey is classified as being more
than 48 km. In addition, five of the eleven bears in the study that were traveling with cubs
lost their young along the way, which signifies a 45 percent mortality rate; only about 18
percent of cubs die that are not forced to swim long distances. If the current warming
trends continue, swimming distances will only get longer and more difficult for the bears
to endure.
Another problem facing polar bears is related to reproduction. Mulvaney states
that the size of a litter and the odds of reproductive success are linked to the amount of
weight a pregnant bear is able to attain before hibernating in the den. The more fat a
pregnant female is able
to gain, the more energy
she has available to
store and provide for
her cubs. In some areas,
such as the western
Hudson Bay, sea ice has
been melting earlier in
the summer and
freezing later in the winter. Because of this, polar bears do not have as much time to eat
and build up the necessary fat. According to Mulvaney, polar bears in the western
Hudson Bay are currently being forced to come ashore and enter the den two weeks
earlier than 20 years ago. It is predicted that they will have to come ashore a whole month
earlier by 2060, and as a result up to 73 percent of females will not be able to reproduce.
Polar bears were classified as a vulnerable species by the IUCN Polar Bear
Specialist Group (PBSG) in 2005, meaning that extinction could occur due to sea ice
changes. In May of 2008 they were listed as a threatened species under the Endangered
Species Act by the U.S. Department of the Interior. They are also considered a species of
concern in Russia. The PBSG determined in 2009 that 8 out of the 19 subpopulations of
polar bears were declining; by comparison, only 5 of the subpopulations were declining
in 2005. The most current estimate of polar bear population is about 20,000, however,
experts believe that two-thirds of the world’s polar bear population could vanish by 2060
if current trends in climate change persist and sea ice continues to melt.
There have been a number of efforts focused on the protection and preservation of
polar bears. Many early projects tracked individual bears by means of a satellite collar,
which was dangerous both to researchers and the animals. The most recent mission,
called Warm Waters for Cool Bears, instead uses meteorological data and satellite
imagery to observe trends in sea ice shrinkage. A Science Daily article entitled “Want to
Save Polar Bears? Follow the Ice” indicates that the goal of the project is to distinguish
where sea ice will likely persist in the future. After those locations are determined,
conservation efforts will be carried out in those specific areas as they will be most
effective at protecting the polar bears there. The bears in more vulnerable locations will
be left to suffer.
Although the odds are working against them, there remains some hope for the
survival of polar bears. Steven Amstrup, the chief scientist of the Polar Bears
International conservation organization, has determined that sea ice deterioration has a
chance of being slowed, if not completely stopped, by reducing greenhouse gas
emissions. However, Mulvaney states that atmospheric carbon dioxide concentrations are
now worse than what was ever predicted. In fact, the quantity of emissions has been
increasing drastically, and the jump between 2009 and 2010 was the largest seen since
the Industrial Revolution. Polar bears are truly amazing creatures, one of the few that can
survive and prosper in extreme Arctic conditions. Unfortunately, if the current trend of
greenhouse gas emissions persists and sea ice continues to melt, polar bears may have no
place to call home in the future; their complete extinction is a very real possibility.
About the Author
Karen Bunavage is a senior at Penn State majoring in meteorology with an option in
weather risk management; she is also pursuing a minor in energy, business, and finance.
Karen has been interested in climate change ever since Al Gore’s An Inconvenient Truth
was released many years ago. During her time at Penn State she learned more about the
subject of climate change in her classes. Karen even had the opportunity to partake in
atmospheric chemistry research, which is a subject closely tied to Earth’s increasing
temperatures. Karen hopes to attend graduate school and focus her studies in a related
area.
Works Cited
Climate Change - Impact on Canada. World Wildlife Fund. Web. 8 Feb. 2012.
<http://wwf.ca/conservation/global_warming/impact/nature/>.
Climate Change. Canadian Wildlife Federation. Web. 8 Feb. 2012. <http://www.cwffcf.org/en/conservation/climate-change/>.
Earth Observatory. NASA. Web. 26 Jan. 2012.
<http://earthobservatory.nasa.gov/IOTD/view.php?id=5620>.
Global Warming. NOAA National Climatic Data Center. Web. 8 Feb. 2012.
<http://www.ncdc.noaa.gov/oa/climate/globalwarming.html>.
Mulvaney, Kieran. "Big Question for 2012: Is the Polar Bear Doomed?" Discovery
News, 12 Dec. 2011. Web. 26 Jan. 2012. <http://news.discovery.com/earth/polarbear-doomed-2012-111212.html>.
Polar Bears. Polar Bears International, 2012. Web. 26 Jan. 2012.
<http://www.polarbearsinternational.org/polar-bears/polar-bears>.
"Want to Save Polar Bears? Follow the Ice." Science Daily, 31 May 2007. Web. 26 Jan.
2012. <http://www.sciencedaily.com/releases/2007/05/070531095420.htm>.
"Watching Earth's Climate Change in the Classroom." NASA. Web. 26 Jan. 2012.
<http://www.nasa.gov/vision/earth/everydaylife/climate_class.html>.