Polar Regions

POLAR REGIONS (ARCTIC AND ANTARCTIC)

Here are highlights of the projected impacts of climate change on the polar regions based on the Fourth Assessment Report of the IPCC (see first box on top right of screen).

Geophysical impacts. In the Polar Regions, the main projected effects are reductions in thickness and extent of glaciers and ice sheets, and changes in natural ecosystems with detrimental effects on many organisms including migratory birds, mammals and higher predators. In the Arctic, additional impacts include reductions in the extent of sea ice and permafrost, increased coastal erosion, and an increase in the depth of permafrost seasonal thawing.

Way of life. For human communities in the Arctic, impacts, particularly those resulting from changing snow and ice conditions, are projected to be mixed. Detrimental impacts would include those on infrastructure and traditional indigenous ways of life. Beneficial impacts would include reduced heating costs and more navigable northern sea routes.

Ecosystems. In both polar regions, specific ecosystems and habitats are projected to be vulnerable, as climatic barriers to species invasions are lowered.

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Antarctic Peninsula – rapid warming in a pristine environment

Gerlache Strait on the Antarctic Peninsula. Photographer: David Mobley, Jet Propulsion Laboratory/NOAA

The Antarctic Peninsula is a rugged mountain chain generally more than 2,000 m high, differing from most of Antarctica by having a summer melting season. Summer melt produces many isolated snow-free areas, which are habitats for simple biological communities of primitive plants, microbes and invertebrates, and breeding grounds for marine mammals and birds. The Antarctic Peninsula has experienced dramatic warming at rates several times the global mean. Since the Third Assessment Report of the IPCC was released, substantial progress has been made in understanding the causes and profound impacts of this warming.

Since records began, 50 years ago, mean annual temperatures on the Antarctic Peninsula have risen rapidly; >2.5°C at Vernadsky (formerly Faraday) Station. On the west coast, warming has been much slower in summer and spring than in winter or autumn, but has been sufficient to raise the number of positive-degree-days by 74%, and the resulting increase in melt has caused dramatic impacts on the Antarctic Peninsula environment, and its ecology.

Scientific observations strongly imply that the retreat is not simply due to cyclic variations in local climate, and that recent warming is unique in the past 10,000 years. The warming processes acting in this region appear correlated with changes in a weather system due to human influence.

If warming does continue (especially in the summer) there will be significant impacts; retreat of coastal ice and loss of snow cover would result in newly exposed rock and permafrost – providing new habitats for colonisation by expanding and invading flora and fauna. However, the direct impacts of climate change on the flora and fauna are difficult to predict, since these ecosystems are subject to multiple stressors. Trends in the marine ecosystems west of the Peninsula include reduced sea-ice cover, the likely cause of dramatic change in the balance between krill and salps, which graze on phytoplankton. Loss of krill will probably have impacts on higher predators such as seals, albatross, penguins and whales, as well as possibly more far-reaching impacts, perhaps even affecting CO2 sequestration in parts of the Southern Ocean.

The rate of warming on the Antarctic Peninsula is among the highest seen anywhere on Earth in recent times, and is a dramatic reminder of how subtle climate-dynamic processes can drive regional climate change, and the complexity of its impacts in an environment where human influence is at a minimum.

More details and citations may be found here: Case study: Antarctic Peninsula – rapid warming in a pristine environment.

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