11 September
2009 - Mountain avens. Arctic warming in
recent decades has had a great impact on
the species. The growing season in the High
Arctic in some places starts considerably
earlier and plants such as Arctic bell heather
(Cassiope tetragona) and mountain avens
(Dryas octopetala) now start blooming two-three
weeks earlier. Photo: Mads C. Forchhammer.
By Steen Voigt
Nine researchers from
Denmark’s National Environmental Research
Institute (NERI), Aarhus University form
part of a team of world-leading Arctic researchers
presenting an overall status of the observed
climate effects on Arctic plants, animals
and ecosystems in the latest issue of Science.
NERI's polar researchers
primarily have Greenland as the location
for their work, especially in and around
the Zackenberg research station in North-east
Greenland, while the remaining Danish and
international colleagues contribute to the
four-page-long article in Science with results
from other parts of the Arctic.
The status featured in
Science is a direct result of the conference
’After the Melt’, held by NERI at Aarhus
University last summer in connection with
the International Polar Year (IPY). Here,
scientists from around the world presented
the newest research results concerning the
significance of global warming for the Arctic
flora and fauna, ecosystem and food chain
changes, and exchange of greenhouse gases
such as CO2 and methane in Arctic areas.
Numerous changes
Climate change in the Arctic takes place
much faster than in other places around
the globe. Snow cover on land and sea ice
have declined dramatically over the last
30 years as a result of progressive warming
in the Arctic. Warming has led to a large
number of conspicuous ecological changes
but also less visible, more indirect changes
for e.g. animals and plants. Changes that
have only been able to be detected by means
of ecosystem observations over a number
of years, such as those carried out since
the mid-11000s at Zackenberg and Kangerlussuaq.
Here, NERI's researchers
have, for example, demonstrated that spring
is arriving progressively earlier, with
consequences in turn for the appearance
of a range of plants and insects in spring.
Also in West Greenland, near Kangerlussuaq,
plants are blooming earlier due to higher
temperatures, whereas the reindeer population
has not yet managed to adapt the timing
of calving to the earlier plant growth.
The result has been a reduced number of
births and increased mortality among calves.
Good for reindeer, bad
for polar bears
’The great strength in our status article
is that it summarizes the consequences for
many land, freshwater and marine organisms
and their environment in the Arctic’, say
two of the authors from NERI, Professor
Mads C. Forchhammer and Professor Eric Post.
’The polar bear is a good example of how
wrong it can go, as both survival and reproduction
rates have fallen due to the rapidly shrinking
sea ice. But effects of warming in the Arctic
can go both ways. For reindeer in Svalbard,
increased periodic melting of snow cover
has over recent years increased the reindeer’s
access to the plant food sources, and birth
as well as survival rates have risen. Similarly,
migrating species such as geese benefit
from the warming because longer summer seasons
in the breeding grounds give more offspring
and greater area in which to breed.’
Further change to come
’Another interesting angle brought to light
in the article in Science is that the effect
of warming on all the ways of life of the
various organisms contributes to changes
in the composition and function of Arctic
ecosystems. And with the migration of more
southerly species northwards there is no
doubt that further change is in store for
Arctic ecosystems’, explain Mads C. Forchhammer
and Eric Post.'
The researchers conclude
the article with a summary of a range of
scientific areas that should be focused
upon in future research on climate impacts
in the Arctic, including conservation, trophic
interactions, ecological dynamics outside
the growing season, the ability of ecosystems
to withstand climate change and the significance
of extreme events. Systematic, long-term
baseline studies, like those carried out
at Zackenberg, are mentioned as one of the
most informative professional tools in assessing
the ecological consequences of a progressively
warmer Arctic.
Ecological Dynamics
Across the Arctic Associated with Recent
Climate Change. Eric Post, Mads C. Forchhammer,
Syndonia Bret-Harte, Terry V. Callaghan,
Torben R. Christensen, Bo Elberling, Anthony
D. Fox, Olivier Gilg, David S. Hik, Toke
T. Høye, Rolf A. Ims, Erik Jeppesen,
David R. Klein, Jesper Madsen, A. David
McGuire, Søren Rysgaard, Daniel E.
Schindler, Ian Stirling, Mikkel P. Tamstorf,
Nicholas J.C. Tyler, Rene van der Wal, Jeffrey
Welker, Philip A. Wookey, Niels Martin Schmidt,
Peter Aastrup. Science. Vol 325. 11 September.
2009.
Related articles on
www.dmu.dk:
USA funding to study
ecological effects of climate change in
Greenland
Climate change leads to contrasting changes
in duration of the growing season and species'
life cycles
Global opvarmning giver større edderkopper
(in Danish)
NERI is taking over the scientific coordination
of the monitoring of climate effects in
Greenland
Klimaændringerne vil medføre
store forandringer i Nordøstgrønlands
natur (in Danish)
Reindeer at Kangerlussuaq
have not adjusted calving time to the earlier
arrival of the plants in spring with negative
consequences for the population. In other
locations, e.g. Svalbard, the warmer winters
have a positive influence on reindeer, as
access to their source of plant food in
winter has improved. Photo: Mads C. Forchhammer.
Volume 13 no. 15, 11 September 2009
