Despite ozone hole's brakes on Antarctic warming, plants grow

More plants and animals are showing up on the western Antarctic Peninsula as the planet warms and summer snows turn to rain, according to a newly released comprehensive review of the state of the polar continent’s climate.

The review, “Antarctic Climate Change and the Environment,” also finds that Antarctica is likely to have warmed far more if it weren’t for the ozone hole, which has delayed the effects of climate change.

“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,” said John Turner of the British Antarctic Survey, who was lead editor of the review. “There is no doubt that our world is changing and human activity is accelerating global change.”

Turner added, “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.”

Published today by the Scientific Committee on Antarctic Research (SCAR), the report reviews the latest evidence from 100 top scientists from 13 countries.

“Antarctica is an unrivalled source of information about our planet,” said Colin Summerhayes, SCAR’s executive director. “This review describes what we know now and illustrates how human activity is driving rapid climate change … The work is particularly important because it puts Antarctic climate change into context and reveals the impact on the rest of the planet.”

Among the review’s top 10 findings:

1. The hole in the ozone layer has shielded most of Antarctica from global warming by altering wind and weather patterns.
2. As the Southern Ocean continues to warm and develops less ability to absorb carbon dioxide, it could contribute to a rise in “alien” species that will compete with native Antarctic wildlife.
3. Rapid warming along the western Antarctic Peninsula, along with a switch from snowfall to rain during summer, has led to an 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. Warmer ocean temperatures have caused significant thinning of the West Antarctic Ice Sheet, particularly around the Amundsen Sea Embayment.
5. Stronger winds caused by the ozone hole have led to a 10 per cent increase in Antarctic sea ice extent since 1980.
6. Atmospheric levels of both carbon dioxide and methane are higher than they’ve been in the past 800,000 years, and are rising at rates unlikely to have been seen in the geologically recent past.
7. The loss of sea ice west of the Antarctic Peninsula has caused changes in algal growth and driven a shift from larger to smaller species. Stocks of krill have declined significantly and Adélie penguin populations have also declined on the northern Antarctic Peninsula, though they remain stable or increased elsewhere.
8. As the ozone hole heals over the remainder of this century, Antarctica is likely to warm by around 3 degrees C. However, that won’t be enough to melt the main ice sheet, and a predicted increase in snowfall there should offset sea level rise by a few centimetres.
9. Loss of ice from the West Antarctic ice sheet, on the other hand, is likely to raise global sea levels by some tens of centimetres by 2100. This will contribute to a projected total sea level rise of up to 1.4 metres (and possibly higher) by century’s end.
10. The polar regions need much more monitoring to help scientists better understand the processes at work there. Climate variability at the poles is larger than in other parts of the world, yet these remote regions are sparsely sampled. A detailed understanding of past climate is also crucial for understanding this distinction, as is a significant refinement of currently crude climate models.