Three sheets to the wind
The ice is melting. All over the world the ice is melting as our planet warms. And sooner than you think, the world will no longer have vast fields of glaciers to air condition and cool its ecosphere.
There are three main ice fields that contain 98% of all the fresh water and 99 per cent of the glaciers on Earth. They are, in order of increasing size, the Western Antarctic, the Greenland and the Eastern Antarctic ice sheets. Each ice sheet is unique and contains more fresh water that all the lakes and rivers of the world combined. Each has its own history, effects and fate. Each one has the potential to change life on the Earth in ways that stagger the imagination.
Greenland, the largest island in the world, and considered to be one of the prime global thermostats, has the second largest ice sheet on the planet. The incredible Global Conveyor and its off-shoot the Gulf Stream are inexorably tied to what is happening on the Greenland ice sheet. In the past decade the melt has increased by a factor of ten, pouring in 2005, almost 200 cubic kilometres of freshwater into the North Atlantic, capping the major source of heat and energy to much of North America and Europe, posing a dire threat and paradoxically putting us at risk of falling into a devastating ice age. It is thought that almost 30 times in the past three million years, the entire Greenland sheet has melted in the space of a century. Are we on the threshold of another such spectacle?
The Western Ice Sheet has occupied the Western Antarctic for three million years. And while the massive ice advances of the Ice Ages have ebbed and waned, it has remained and endured. So great is the mass of ice that sit on Western Antarctic, that most of that part of the Antarctic is pushed a kilometre below sea level and its ice fields rest on a slurry of water greased gravel. The Larsen, Ross and Ronne ice shelves, larger in total area than Spain, France and Germany combined, push out into the South Atlantic and Pacific and fill scientists with trepidation and fear. New satellite data shows they are riddled with a honey comb of rivers and lakes of melted fresh water, lubricating some of the fastest flowing glaciers on the planet. In 2004 the Larsen B shelf collapsed and researchers gasped. Was it a portend of things to come?
The Eastern Antarctic ice sheet is the mother of all ice. It is a Behemouth. 80% of all the ice in the world, enough to raise the ocean levels 100 metres, exists on its plateau. It has been there for a staggering 45 million years, almost since the time of the dinosaurs. It is the oldest ice on Earth. Its permanence is astounding. The oldest ice cores, dating back almost 700,000 years, are collected from its incredible, slow moving fields. Lake Vostok, below the most inaccessible ice station station in the world, Vostok, is the largest, totally submerged, pristine lake in the world, cut off from the surface for more than one hundred thousand years. Ever since Antarctica drifted over the Earth’s South Pole there has been permanent ice on the Eastern Antarctic. Is it threatened? Can even its permanence wither in the face of the onslaught of climate change? Or will it grow and kick us back into another series of unstable weather patterns and another round of global ice advance?