Footprints of climate change in the Arctic region

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The Arctic region is home to many unique, diverse and vulnerable ecosystems. But the enigmatic and once pristine Arctic environment is being increasingly affected by human activities. This thematic issue presents the latest research into the impacts of climate change and resource extraction on Arctic biodiversity and indigenous communities.

The timing of this special issue reflects the EU’s growing engagement in the Arctic following the 2008 Communication ‘The EU and the Arctic Region‘, the Council Conclusions of 2009 and the European Parliament’s 2011 report on the High North. The forthcoming Joint Communication of the High Representative and the Commission, due in May 2012, will review recent progress and the next steps towards developing an EU policy towards the Arctic regions. Across the globe, the effects of climate change are becoming increasingly apparent. But nowhere has the effect been felt more strongly than in the Arctic. During the 20th century, land temperatures rose by an average of 1-2°C across the entire Arctic1, which is twice as fast as the average global temperature rise. Perhaps the most emblematic impact of climate change is the rapid loss of sea ice.

At the current rate of decline, the Arctic is expected to be ice-free in summer by 2040, and some experts believe that it could be much sooner.

ice2The first article entitled “Declining sea ice threatens Arctic marine mammals” explores the consequences for marine mammals, such as whales, polar bears and seals, which depend on sea ice for feeding, shelter and breeding. Collaborating with Arctic communities may be one way to increase the number of marine mammal population studies, which have so far been limited by financial and logistical difficulties.

Loss of sea ice will also affect far less visible elements of the Arctic ecosystem. “Arctic microbes: Good or bad for mitigating climate change” describes the shift in community dynamics that is occurring within microbial populations deep within the ice. The ecological impact of climate change is increasingly evident in alterations to species migration patterns.

“Arctic birds migrate earlier under climate change” describes how migrating birds are arriving in the Arctic nearly half a day earlier each year in response to rising spring temperatures, which has significant implications for annual breeding cycles.

ice3The different Arctic subzones are home to many native plant species, including wild flowers, shrubs, grasses, mosses and lichen. Some studies predict the trend towards longer and warmer summers will result in an overall “greening” of the Arctic. However, as the article “Reindeer are important in shaping Arctic plant communities” describes, individual species distribution depends on many factors, including the grazing and trampling habits of native reindeer, with the implication that reindeer grazing management strategies could be important in biodiversity protection measures.

Scientists predict that short-lived periods of extreme winter warming will become more frequent under climate change, during which temperatures can rise up to 10°C in 24 hours.

These warming events can cause physiological changes in some dominant shrub species, decreasing their freeze-tolerance and reducing growth and survival over time. This is discussed in the article “Extreme winter warming harms Arctic plant growth”. As the articles “Polar and Atlantic cod share habitat, but not diet” and “Climate warming may enhance survival of polar cod” explain, the impact of climate change on native polar cod is uncertain.

Polar cod do not appear to be in competition for prey with Atlantic cod species, which have shifted their distribution northwards in search of cooler waters.

However, this may change if the populations continue to converge. On the other hand, warmer conditions in winter favour the growth and survival of polar cod hatchlings in a phenomenon known as the thermal refuge hypothesis.

The Arctic is very closely linked to global climate. Frozen sediment, known as permafrost, is beginning to thaw in response to rising temperatures, releasing vast amounts of methane into the atmosphere. Since methane is a far more potent GHG than CO2, the release of even a fraction of the 2000 billion tonnes2 stored in the permafrost could trigger a ‘positive feedback’ mechanism, dramatically accelerating the pace of climate change.

This is explained in more depth in “Arctic methane leak could cause abrupt climate warming”. From a different global climate perspective, the Arctic is estimated to contain 30% of the world’s undiscovered gas reserves and 13% of undiscovered oil. Dwindling supplies elsewhere and the fact that declining sea ice is making remote parts of the Arctic increasingly accessible means that many Arctic countries are looking to exploit their vast Arctic resources, despite commitments to reduce GHG emissions under the Kyoto Protocol (excluding the United States).

“Arctic exploration: How far and how fast?” explores the costs and risks of Arctic development and how pressure from scientists and environmental groups for sustainable development is shaping the industry.

The final article, “Reindeer herding: adapting to climate change in the Arctic” examines the impact of climate change and the expansion of industrial activities on the indigenous Arctic population. In response to declining reindeer numbers, a unique international initiative is helping native communities adapt to local environmental changes using state-of-the-art satellite observation equipment and working to increase indigenous participation in policy decisions.

Arctic environmental issues will continue to attract wide interest in the EU and elsewhere during 2012-13. Of particular importance is the International Polar Year conference in Montreal in April 2012, where key policy areas covered by this special issue will be discussed, including biodiversity, climate mitigation and adaptation, sustainable development and resource management.

Many of the articles covered in this issue are part of on-going research under the EU Arctic Tipping Points project.

Other important EU-funded projects focus on the contribution of continental ice melt to sea level rise (Ice2Sea), the effects of climate change on stratospheric ozone depletion (RECONCILE) and the probability of a reduction in the strength of the Meridional Overturning Circulation, the global conveyor belt system that transports heat around the globe and provides northern Europe with its characteristically mild climate (THOR).

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