Winners & losers of Antarctica’s thaw
Hyderabad: When we think of Antarctica, we picture vast, continuous ice sheets and glaciers, with maybe a penguin or two thrown in. Yet most Antarctic plants and animals live in the permanently ice-free areas that cover about 1% of the continent. A new research predicts that due to climate change more than 17,000 square km […]
Hyderabad: When we think of Antarctica, we picture vast, continuous ice sheets and glaciers, with maybe a penguin or two thrown in. Yet most Antarctic plants and animals live in the permanently ice-free areas that cover about 1% of the continent. A new research predicts that due to climate change more than 17,000 square km of new ice-free area could emerge across the continent by 2100.
Flora & Fauna
Besides Emperor and Adelie penguins, terrestrial Antarctic species also include mosses, lichens, two types of flowering plants, and invertebrates such as nematodes, springtails, rotifers and tardigrades, many of which are found nowhere else on Earth.
Ice Area
Antarctica’s ice-free areas are currently limited to a scattering of rocky outcrops along the coastline, or cliff faces, or the tops of mountain ranges. They form small patches of suitable habitat in a huge sea of ice.
As a result, the plants and animals that live there are often isolated from each other. But as Antarctica’s climate warms, we expect ice-free areas to get bigger and eventually start joining up. This would create more habitat for native species, but also new opportunities for non-native species to spread.
New World
Thawing definitely will provide new opportunities for some native plants and animals to expand their range and colonise new areas.
The warming climate may also give a boost to species that are currently hampered by the lack of warmth, nutrients and water. Some Antarctic mosses, for example, are expected to grow faster as temperatures rise, and Antarctica’s two flowering plant species are already expanding southward. However, the potential benefits seem likely to be outweighed by the negatives. The joining-up of habitat patches could allow species that have been isolated for much of their evolutionary past to meet suddenly.
If the newcomers to a particular area out compete the native species, then it may lead to localised extinctions. Over the coming centuries this could lead to the loss of many plants and animals, and the homogenisation of Antarctica’s ecosystems.
Aliens
Antarctica’s great thaw could provide new opportunities for species to invade. Antarctica’s best bulwark against non-native species is its harsh climate and extreme weather, to which native Antarctic species have spent many thousands of years adapting.
We already know that many plants and invertebrates are reaching Antarctica, most often in food or cargo shipments. As the climate warms, some of these non-native species may be able to establish themselves on the Antarctic Peninsula, and the increasing connectivity will allow them to easily move through the landscape. Many of these animals and plants may become invasive, competing with the native species for space and resources.
We don’t know how Antarctica’s species will cope with the increasing competition. But if the sub-Antarctic islands provide any indication, the outlook is depressing. Australia’s World Heritage-listed Macquarie Island, for example, was severely impacted by invasive cats, rats, rabbits and mice.
Several non-native species have already come to Antarctica, including the invasive annual meadowgrass Poa annua (a common weed around the world), which has colonised newly ice-free areas left behind by retreating glaciers.
Humans – both scientists and tourists – are key transporters of non-native species to the continent, and tourist numbers continue to grow (almost 37,000 visited in the 2016-17 summer).
Biosecurity is paramount for the ongoing protection of Antarctica. If bags, shoes, clothes and field equipment are not properly cleaned and inspected before arriving on the continent, then non-native seeds, microbes and insects could be transported to Antarctica and begin to spread.
