Adelie penguin babies, Antarctica.
The ocean and its inhabitants will be irreversibly affected by
the impacts of global warming and climate change. Scientists say
that global warming, by increasing sea water temperatures, will
raise sea levels and change ocean currents.
The water in our world's oceans is always moving - pulled by
tides,blown by waves, and slowly circulating around the globe by
the force ofthe Great Ocean Conveyor Belt (also called thermohaline
circulation).The Conveyor is powered by differences is water
temperature andsalinity, and one of its most well known parts, the
Gulf Stream, iswhat gives Europe it's relatively mild climate.
Aside from keeping Europe warm, and playing an important role in
theglobal climate, the Conveyor provides an up welling of bottom
oceannutrients, and increases the oceanic absorption of carbon
What could go badly wrong
Worryingly, recent studies warn that we may already have
evidence of aslower Conveyor circulation over the
Scotland-Greenland deep oceanridge. And while the Conveyor appears
to have operated fairly reliablyover the past several thousand
years, an examination of ice cores fromboth Greenland and
Antarctica shows that this has not always been thecase. In the more
distant past, changes to the Conveyor circulation areassociated
with abrupt climate change.
In short, dilution of the ocean's salinity - from melting Arctic
ice(such as the Greenland ice sheet) and/or increased precipitation
-could switch off, slow down or divert the Conveyor. This
dramaticcooling would mean a massive disruption to European
agriculture andclimate, and impact other sea currents and
temperatures around theglobe.
Sea Level Rise
A global average sea level rise of 9-88 cm (3.5-34.6 inches)
isexpected over the next hundred years, thanks to the greenhouse
gasseswe have emitted to date and likely future emissions. This
will come inroughly equal measure from melting ice and from thermal
expansion ofthe oceans (water expands as it heats up).
Even this comparatively modest projected sea level rise will
wreakhavoc. Coastal flooding and storm damage, eroding
shorelines,salt water contamination of fresh water supplies,
agricultural areas,flooding of coastal wetlands and barrier
islands, and an increase inthe salinity of estuaries are all
realities of even a small amount ofsea level rise. Some low lying
costal cities and villages will also beaffected. Resources
critical to island and coastal populationssuch as beaches,
freshwater, fisheries, coral reefs and atolls, andwildlife habitat
is also at risk.
The West Antarctic ice sheet
Only four years ago, it was commonly accepted that the West
Antarcticice sheet was stable, but unexpected melting in the region
is causingscientists to re-think this assumption.
In 2002, the 500 billion tonne Larsen B ice shelf, which covered
anarea twice the size of greater London, disintegrated in less than
amonth. This did not directly add to sea level rise since the ice
shelfwas already floating, but it was a dramatic reminder of the
effects ofwarming in the area.
Then in 2005, the British Antarctic Survey released findings
that 87percent of the glaciers on the Antarctic Peninsula have
retreated overthe past 50 years. In the past five years, the
retreating glaciers havelost an average of 50 metres (164 feet) per
Potentially, the West Antarctic ice sheet could contribute
anadditional six metres (20 feet) to sea level rise. Although
thechances of this are considered low in the Intergovernmental
Panel onClimate Change's Third Assessment report, recent research
indicates newevidence of massive ice discharge from the ice sheet.
The entire Antarctic ice sheet holds enough water to raise
global sea levels by 62 metres (203 feet).
The Greenland glaciers
In July 2005, scientists aboard the Greenpeace ship Arctic
Sunrise madea stunning discovery - evidence that Greenland's
glaciers aremelting at an unprecedented rate. It's just more
evidence that climatechange is no longer on the horizon, it has
arrived at our doorstep, andif you live in a coastal city, that's
not just a figure of speech.
Findings indicated that the Kangerdlugssuaq Glacier on
Greenland's eastcoast could be one of the fastest moving glaciers
in the world with aspeed of almost 14 kilometres per year. The
measurements were madeusing high precision GPS survey methods. In
addition, the glacierunexpectedly receded approximately five
kilometres since 2001 aftermaintaining a stable position for the
past 40 years.
Greenland's massive ice sheet locks up more than six percent of
theworld's fresh water supply, and it is melting much faster
thanexpected. If Greenland were to melt fully, it would cause sea
levelsaround the globe to rise by nearly 20 feet. Even measurements
of fourto five feet of sea level rise could mean that places like
New York,Amsterdam, Venice and Bangladesh will experience flooding
in low lyingareas.
The alarming retreat of the Kangerdlugssuaq Glacier suggests
that theentire Greenland ice sheet may be melting far more rapidly
thanpreviously believed. All current scientific forecasts for
globalwarming had assumed slower rates of melting. This new
evidence suggeststhat the threat of global warming is much greater
and more urgent thanpreviously believed.
Temperature rises are impacting on the entire marine food web.
Forexample, phytoplankton, which feeds small crustaceans including
krill,grow under sea ice. A reduction in sea ice implies a
reduction in krill- and krill feeds many whale species, including
the great whales.
Whales and dolphins strand themselves in high temperatures. The
greatwhales also risk losing their feeding grounds, in the Southern
Oceanaround Antarctica, because of the melting and collapse of ice
Whole species of marine animals and fish are directly at risk
due tothe temperature rise - they simply cannot survive in warmer
waters.Some penguin populations, for example, have decreased by 33
percent inparts of Antarctica, because of habitat decline.
An increasing occurrence of disease in marine animals is also
linked to rising ocean temperatures.