Published on April 21st, 2011 | by Yellow Magpie1
The Melting Ice: The Harsh Reality Of Global Warming
All around the world, a slow destructive drip is turning into a torrent. As humans irrevocably change our landscape, the massive ice sheets are starting to disappear. With this comes untold devastation and an impact that will be felt by more than one-third of the world’s population.
Many scientists are now coming to the conclusion that these changes cannot be reversed and that we have now become passengers in a run-away behemoth of our own creation.
No Longer Slow-Moving
The normal preconceptions that surround ice-sheets and glaciers are that they are almost immeasurably slow-moving, glacial, after all, is a well-known adjective. Sadly, recently this slow-moving notion has been firmly dispelled. These harsh, seemingly desolate ice-worlds are places that are constantly in flux, during the summer when huge melt-water lakes appear and suddenly disappear within minutes.
The thing that is most concerning is the rapid acceleration of change within the last decade or so.
These changing rates have been catalogued and we now have accurate projections of what will happen. Timescales have been drawn up but they could well be too conservative.
Changes in the ice have always been part of the life-cycles of the Earth. But what is different is that humans, for the first time, appear to be the drivers of climate change. The ultimate cause of this temperature rises is the burning of fossil fuels.
Some of the most extreme changes can be seen off the west coast of Alaska. Over the four preceding decades temperatures have soared by two degrees Celsius. This is twice the rate of the global average. These rises in temperature are having a dramatic effect on glaciers and huge chunks or ice are falling into the sea, calving, at an unprecedented rate. The increase in calving is the main contributor to rising sea levels.
One of the most famous glaciers is the Columbia in Alaska. Since the 1980’s the glacier has been losing more ice than is being replaced by snowfall. Scientists have been measuring the speed of the glacier over several years and they have discovered that it has sped up from a rate of 2 metres per day in the 1980’s to its current rate of 16 metres per day.
The Columbia has receded over 16 kilometres during the last three decades. From May 2007 to May 2008, the Columbia Glacier was reduced by over one kilometre.
The Root Cause
Using earthquake monitoring equipment scientists have discovered that water is the main cause of the increased calving. Increased melting on top of the glacier caused the water to rush into the ice, splitting and fracturing it. The water also provides lubrication increasing the speed of the glaciers movement towards the open water.
Some scientists believe that the Columbia Glacier has no future and has long since reached its tipping point, a place of no-return.
What Will No Glaciers Mean?
The destruction of the Columbia Glacier is being echoed all across the world. It is now conservatively estimated that all the world’s glaciers will disappear within the next 50 years. Thus rising sea levels by 30 centimetres. Just this small loss will be devasting to low-lying island communities. But the true cost will be the lack of water for well over one billion people scattered across continental Europe and Asia. People who depend on glaciers for the supply of water. In Asia-alone, one billion people will be directly affected.
The Ice Sheets
However, the real problems are centred on the huge ice sheets of Antarctica, the Artic and Greenland. To put their size in context, if these colasal ice-sheets were to completely melt, the world’s sea levels would rise by an truly apocalyptic 60 metres. Previously, scientists thought that these sheets were simply too large to melt. However, this belief has taken a battering recently as a growing body of evidence suggests otherwise.
Larsen B And Greenland
In 2002, a huge portion of the ice sheet in Antarctica, dubbed Larsen B, completely tore its self from the main sheet. The piece was the size of Luxembourg.
Despite this extraordinary precedence it would not be the only collapse either, as huge portions of the ice shelves would become separated from the main sheet. Thus thescientific estimates that it would take thousands of years for the ice sheets to melt were turned instantly on their head.
Greenland has also borne the brunt of global warming. In the last decade alone, the country has experienced temperature rises of three degrees. Summers in Greenland are odd times. The hot sun melts the top of the ice sheets causing huge lakes to appear. These meltwater lakes pour through the ice drilling their way through until they reach the bedrock, hundreds of metres below the top of the sheet. The water that gathers from the meltwater lakes acts as a lubricant increasing the speed at which the ice enters the open waters.
The Earth’s Ice History
Ice core samples confirm the cycles of ice ages. These cores provide clear links between rises in greenhouse gases such as CO2 and increasing rises in global temperatures. These reach peaks every 100,000 years or so. At every peak between both CO2 and temperature levels, rises in sea levels followed. The last melting of the ice sheets occured roughly 125,000 years ago. During this period the entire southern portion of Greenland melted and sea levels rose by three metres.
What’s clear though, is that the levels of greenhouse gases have never been as high as they are now. This is a firm indication that the temperature rises are caused by humans.
It is believed that Greenland lost muich of its ice over a period of several centuries if not one thousand years. The next loss however is promising to be very different.
Disappearing Before Our Very Eyes
These highly dynamic systems are best observed through the use of time-lapse cameras. Jakobshavn in Greenland. Jakobshavn is moving at 40 metres per day nearly twice as fast as one decade ago. This is during the melt phase in summer. Greenland is experiencing a net lose of 150 billion tonnes of ice a year.
In 2008, the largest calving event ever filmed was recorded by David Balog as a section of Glacier, the size of Manhattan Island in New York, tore away from the ice.
How Is The Ice Disappearing?
The melting lakes and water is providing roughly ten per cent of the loss of ice. The other 90 per cent can be attributed to jumps in coastal water temperatures.
In 1997 there was a jump of 1.7 degrees in coastal temperatures which also coincided with the increasing speed in ice calving.
Scientists have discovered that it is the interplay between the cold ice face and the warmer sea waters that is providing the mechanism for the increased ice calving. Near the surface, the water temperature is at its coldest, however, as you go deeper below the surface, the water temperature starts to rise.
Scientists, such as Dr. Ian Howat, now believe that the increased water temperature is providing a convection current. Howat believes that the freezing ice that hits the water’s surface upon calving causes a continuous feedback system. The interaction between the cold and warm water creates a conveyor belt effect that sucks warm water under the base of the ice face, causing it to calve dropping more ice into the water and the cycle endlessly repeats until there is no more ice left.
So, Where Does This Leave Us?
So what does that mean? Conservative estimates state that within 100 years water levels will have risen by 30 centimetres through the lose of our glaciers, a further 30 centimetres through heat causing the oceans to expand and another 30 centimetres through the loss of vast portions of the ice sheets. Fortunately, scientists agree that the polar regions will not melt completely but rather retreat.
With the water almost one metre higher by the year 2100, one billion people’s homes will be under threat from the rising sea levels. Several trillion dollars will be spent on providing sea defences and low-lying regions such as Florida, and Bangladesh will be destroyed. Island communities will entirely disappear.
This scenario could already be certain, the only question that remains is what will people do? Perhaps our greatest challenge will be to adjust our mindset. In future the illusion that we are in control will be well and truly shattered.
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