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First comprehensive review of the state of Antarctica’s climate – Antarctic Climate Change and the Environment


In 2009, the ozone hole reached its 10th largest measured size since careful
measurements began in 1979.The daily maximum ozone hole area for 2009 was 24
million km2 on 17 September. 

 


Antarctica may heat up dramatically as ozone hole repairs

 


The first comprehensive review of the state of Antarctica’s climate and its
relationship to the global climate system is published this week (Tuesday 1
December) by the Scientific Committee on Antarctic Research (SCAR). The review –
Antarctic Climate Change and the Environment – presents the latest research from
the icy continent, identifies areas for future scientific research, and
addresses the urgent questions that policy makers have about Antarctic melting,
sea-level rise and biodiversity. 

 


Based on the latest evidence* from 100 world-leading scientists from eight
countries, the review focuses on the impact and consequences of rapid warming of
the Antarctic Peninsula and the Southern Ocean; rapid ice loss in parts of
Antarctica and the increase in sea ice around the continent; the impact of
climate change on Antarctica’s plants and animals; the unprecedented increase in
carbon dioxide levels; the connections between human-induced global change and
natural variability; and the extraordinary finding that the ozone hole has
shielded most of Antarctica from global warming. 

 


Dr. Colin Summerhayes, Executive Director of the Scientific Committee on
Antarctic Research said, “Antarctica is an unrivalled source of information
about our planet. This review describes what we know now and illustrates how
human activity is driving rapid climate change. By integrating this
multidisciplinary evidence into a single source we will help scientists and
policy makers understand the distinction between environmental changes linked to
the Earth’s natural cycles, and those that are human induced. The work is
particularly important because it puts Antarctic climate change into context and
reveals the impact on the rest of the planet.”

 


Professor John Turner of British Antarctic Survey is the lead editor of the
review. He said,“ For me the most astonishing evidence is the way that one
man-made environmental impact – the ozone hole – has shielded most of Antarctica
from another – global warming. Understanding the complexities surrounding these
issues is a challenge for scientists – and communicating these in a meaningful
way to society and to policymakers is essential. There is no doubt that our
world is changing and human activity is accelerating global change. This review
is a major step forward in making sure that the latest and best evidence is
available in one place. It sets the scene for future Antarctic Research and
provides the knowledge that we all need to help us live with environmental
change.”


A summary of the report’s findings are detailed in the following 10 key points: 

 


1. Hole in ozone layer has shielded most of Antarctica from global warming The
ozone hole has delayed the impact of greenhouse gas increases on the climate of
the continent. Consequently south polar winds (the polar vortex), have
intensified and affected Antarctic weather patterns. Westerly winds over the
Southern Ocean that surrounds Antarctica have increased by around 15%. The
stronger winds have effectively isolated Antarctica from the warming elsewhere
on the planet. As a result during the past 30 years there has been little change
in surface temperature over much of the vast Antarctic continent, although West
Antarctica has warmed slightly. An important exception is the eastern coast of
the Antarctic Peninsula, which has seen rapid summer warming. This warming is
caused by stronger westerly winds bringing warm, wet air into the region from
the ocean. 

 


2. Warming of the Southern Ocean wwill cause changes in Antarctic ecosystem The
largest ocean current on Earth (the Antarctic Circumpolar Current) has warmed
faster than the global ocean as a whole. The Southern Ocean is one of the major
sinks of atmospheric CO2, but increasing westerly winds have affected the
ocean’s ability to absorb CO2 by causing the upwelling of CO2 rich water. If
temperatures continue to rise ‘alien’ species may migrate into the region,
competing with and replacing original Antarctic inhabitants. Key species in the
food chain like planktonic snailscould suffer from ocean acidification. Changes
in the food regime are likely to decrease the rich Antarctic seabed
biodiversity. 

 


3. Rapid increase in plant communities across Antarctic Peninsula Rapid warming
has been seen along the western Antarctic Peninsula, along with a switch from
snowfall to rain during summer, resulting in expansion of plant, animal and
microbial communities in newly available land. Humans have also inadvertently
introduced ‘alien’ organisms such as grasses, flies and bacteria. 

 


4. Rapid ice loss in parts of the Antarctic The West Antarctic Ice Sheet has
significantly thinned particularly around the Amundsen Sea Embayment as a result
of warmer ocean temperatures. Regional warming caused by intensification of the
westerly winds (due to the ozone hole) is melting ice shelves along the eastern
Antarctic Peninsula (e.g. Larsen B Ice Shelf). Overall, 90% of the Peninsula’s
glaciers have retreated in recent decades. However, the bulk of the Antarctic
ice sheet has shown little change. 

 


5. 10% increase in sea ice around the Antarctic Since 1980 there has been a 10%
increase in Antarctic sea ice extent, particularly in the Ross Sea region, as a
result of the stronger winds around the continent (due to the ozone hole). In
contrast, regional sea ice has decreased west of the Antarctic Peninsula due to
changes in local atmospheric circulation and this has also been linked with the
very rapid warming seen over land on the west coast of the Peninsula. 

 


6. Carbon dioxide levels increasing at fastest pace in 800,000 years Atmospheric
concentrations of CO2 and CH4 are at higher levels than experienced in the last
800,000 years and are increasing at rates unlikely to have been seen in the
(geologically) recent past. Antarctica was warmer in the last interglacial
(130,000 years ago) and sea levels were higher, but the contribution of West
Antarctica to that rise is currently unknown. Small-scale climate variability
over the last 11,000 years has caused rapid ice loss, shifts in ocean and
atmospheric circulation and enhanced biological production, showing that
Antarctica is highly sensitive to even minor climate changes. Studies of
sediments under recently lost ice shelves suggest ice shelf loss in some regions
is unprecedented during this time scale. 

 


7. Sea ice loss directly affecting krill levels and penguin colonisation Loss of
sea ice west of the Antarctic Peninsula has caused changes in algal growth. This
loss of sea ice has also caused a shift from large to smaller species. Stocks of
krill have declined significantly. In some areas Adélie penguin populations have
declined due to reduced sea ice and prey species (on the northern Antarctic
Peninsula), but they have remained stable or increased elsewhere (Ross Sea and
East Antarctica). Historical exploitation of seals and whales has changed the
ecosystem, reducing scientists’ ability to fully understand the impacts of
climate change on krill and other species.

 


8. Antarctica predicted to warm by around 3°C over this centuryOver this century
the ozone hole is expected to heal, allowing the full effects of greenhouse gas
increases to be felt across the Antarctic. Models suggest that the net effect
will be continued slow strengthening of winds across the Southern Ocean, while
sea ice will decrease by a third, resulting in increased phytoplankton
productivity. The predicted warming of about 3°C across the continent is not
enough to melt the main ice sheet and an increase in snowfall there should
offset sea level rise by a few centimetres. 

 


9. West Antarctic ice loss could contribute to 1.4 m sea level rise Loss of ice
from the West Antarctic ice sheet is likely to contribute some tens of
centimetres to global sea level by 2100. This will contribute to a projected
total sea level rise of up to 1.4 metres (and possibly higher) by 2100. 

 


10. Improved modelling of polar processes required for accurate predictions
Climate variability in the Polar Regions is larger than in other parts of the
world, yet these remote regions are sparsely sampled. These areas need to be
monitored in much greater detail in order to detect change, to improve
understanding of the processes at work, and to distinguish between natural
climate variability and variability caused by human influences. A detailed
understanding of past climate is also crucial for understanding this
distinction, as is a significant refinement of currently crude climate models. 

 


Scientific Committee on Antarctic Research (SCAR) is the main body dealing with
the international co-ordination of scientific research in Antarctica and the
Southern Ocean. Formed with 12 member countries in 1958 to continue activities
begun during the International Geophysical Year of 1957 – 58, it is an
interdisciplinary committee of the International Council for Science (ICSU) and
now has 35 Member countries. SCAR played a leading role in the recently
completed International Polar Year (2007 – 2008). 

 


British Antarctic Survey (BAS), a component of the Natural Environment Research
Council, delivers world-leading interdisciplinary research in the Polar Regions.
Its skilled science and support staff based in Cambridge, Antarctica and the
Arctic, work together to deliver research that underpins a productive economy
and contributes to a sustainable world. Its numerous national and international
collaborations, leadership role in Antarctic affairs and excellent
infrastructure help ensure that the UK maintains a world leading position. BAS
has over 450 staff and operates five research stations, two Royal Research Ships
and five aircraft in and around Antarctica.

 


Issued on behalf of SCAR and the editors by the British Antarctic Survey Press
Office


http://www.scar.org