Using the Earth as a community toilet is finally having the effects scientists have been warning us about for decades. But as the Earth burns, our leaders have fiddled, frittering away nearly every chance to rein in the destruction before it is too late. Now the point of no return may be upon us. Steve Hanley writing for CleanTechnica
According to new research, storm driven swells have caused the catastrophic collapse of five highly vulnerable ice shelves since 1992, quadrupling the loss of ice in peninsular Antarctica. And, gulp, the collapse can occur in just days. The research found that it is lack of sea ice, which acts as a buffer for the ice platform, that leaves a highly vulnerable ice shelf to “attack” from massive ocean waves “causing them to flex and break”. The research notes that the Southern Ocean generates the largest waves on the planet, “and these waves are becoming more extreme”.
The Conversation writes:
“But where there is loss of sea ice, storm-generated ocean swells can easily reach the exposed ice shelf, causing the first few kilometres of its outer margin to flex.”
“Over time, this flexing enlarges pre-existing fractures until long thin ‘sliver’ icebergs break away or ‘calve’ from the shelf front
“This is like the ‘straw that broke the camel’s back’, triggering the runaway collapse of large areas of ice shelves weakened by pre-existing fracturing and decades of surface flooding.”
The Conversation notes that ice shelf collapse itself does not lead to sea level rise, but with no more resistance pushing back on the ice shelf, the tributary glaciers “accelerate their discharge of land-based ice into the ocean – and this does raise sea levels”.
The Antarctic Peninsula has experienced particularly strong climate warming (roughly 0.5℃ per decade since the late 1940s), which has caused intense surface melting on its ice shelves and exacerbated their structural weaknesses such as fractures. These destabilising processes are the underlying drivers of ice shelf collapse. But they do not explain why the observed disintegrations were so abrupt.
Our new study suggests that the trigger mechanism was swell waves flexing and working weaknesses at the shelf fronts in the absence of sea ice, to the point where they calved away the shelf fronts in the form of long, thin “sliver-bergs”. The removal of these “keystone blocks” in turn led to the catastrophic breakup of the ice shelf interior, which was weakened by years of melt.
Our research thus underlines the complex and interdependent nature of the various types of Antarctic ice – particularly the important role of sea ice in forming a protective “buffer” for shelf ice. While much of the focus so far has been on the possibility of ice shelves melting from below as the sea beneath them warms, our research suggests an important role for sea ice and ocean swells too.
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