News Excerpt:
The study, published in the journal Nature Geoscience, scientists have discovered a new tipping point toward "runaway melting" of Antarctic ice sheets.
More about the news:
- Scientists from the British Antarctic Survey found that warm ocean water is seeping beneath the ice sheet at its “grounding line”.
- A new tipping point toward "runaway melting" of Antarctic ice sheets, caused by warm ocean water intruding between the ice and the land it sits on.
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The models used by the United Nations Intergovernmental Panel on Climate Change (IPCC) to project the impact of global warming on the Antarctic have yet to factor in this phenomenon.
Key findings of the study:
- The study provides that as ocean temperatures rise due to human-caused global warming, Antarctic ice sheets are melting, which threatens a rise in global sea levels and puts coastal communities at risk.
- The increase in ocean temperature can lead to the passing of the tipping point, beyond which ocean water intrudes in an unbounded manner beneath the ice sheet, via a process of runaway melting.
- The Pine Island glacier, currently Antarctica's largest contributor to sea-level rise, is at high risk of melting due to the slope of the land that allows in more seawater.
- However, the study does not give time frames for when the tipping point might be reached, nor does it give figures for how much sea level rise can be expected.
- As the water warms, even by a fraction, the intrusion accelerates from short distances of 100 metres (330 feet) to tens of kilometres (miles), melting ice along the way by heating it from below, explained the study's lead author Alexander Bradley.
- "Every 10th of a degree (of warming) makes these kind of processes closer, these tipping points closer," said Bradley.
- The risk to sea-level rise comes when the accelerated melting outpaces the formation of new ice on the continent.
- Some areas of Antarctica are more vulnerable to this process than others due to the shape of the land mass, which has valleys and cavities where sea water can pool beneath the ice.
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Intergovernmental Panel on Climate Change (IPCC):
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