Greenland, Antarctica and Alaska have lost 1.5 trillion to 2 trillion tons of ice since 2003, according to NASA geophysicist Scott Luthcke. Jay Zwally, a NASA ICESat Project Scientist, says Greenland is losing 150-160 gigatons of ice yearly which equates to a 0.5mm average sea level rise. Zwally adds that, "The best estimates are that sea levels will rise about 18 to 36 inches by the end of the century”, according to a CNN report.
Scott Luthcke uses information from the NASA GRACE satellite that measures Earth’s gravity field from orbit and which can help determine ice mass changes on the planet.
Lower Arctic sea ice coverage means more solar radiation is absorbed rather than reflected, warming the oceans and surrounding land mass. The warmer oceans mean less ice and warmer air above the oceans. The warmer landmass will eventually mean melting permafrost, which will result in the release of methane and further warming of the atmosphere that circulates warm air over the Arctic regions which contributes to sea ice loss in the first place. Frozen lakes and ocean beds also have trapped methane that will potentially be released in enormous quantities. This is part of the ‘tipping point’ that climatologists have described as being critical in terms of runaway climate change on the planet.
Over the last few years the average Arctic air temperature have measurably been warmer. The ice has become thinner by over 40%, and 2008 was the second smallest summer ice coverage on record, marginally larger than the record low set in 2007. The loss of the older, thicker sea ice has been a major indicator of the severity of sea ice loss accelerating. Predictions that sea ice coverage would disappear completely in 20 years time have been revised so that perhaps in as little as 5 years time the Arctic will be ice free in the summer.
A few years ago there was ridicule poured on those who dared mention the melting of the Greenland ice pack, yet few would be brave enough to do so now. Greenland, which is 4 times bigger than France, and covered by 10% of the world’s fresh water, has enough frozen water stored in ice that, should it melt, it will raise sea levels by an estimated 7 meters.
It also seems that this water won’t be evenly distribute around the planet, according to Detlef Stammer (University of Hamburg, Germany) in a New Scientist Magazine article. The article reports that most of Greenland’s melted water, predicted to add 1 meter to sea levels this century, would stay in the Atlantic for at least 50 years, leading to major floods in Europe and North America. It would take about 30 years before the increased sea level rise works its way south and floods low-lying Indian Ocean and Pacific Islands. Stammer said that “The Greenland ice cap is much less of a threat to tropical islands in the Pacific than it is for the coasts of North America and Europe”. The sea level rises around Greenland, Canada and the US would be 30 times the average, and 6 times the average in Europe.
Major changes have been happening for the last few years in the Antarctic too, beginning with the Larsen B ice shelf disintegration in 2002. The West Antarctic Peninsula temperature has increased by 2°C over the last 50 years which is twice the global average, most of the glaciers are retreating and the ice coverage is thinning. Luckily for the planet, and us, most of the ice in the Antarctic is on rock, and the Antarctic climate – in the rest of Antarctic – seems to be resisting temperature change effects for now at least. If the West Antarctic Peninsula were to melt then up to 5 meters of average sea level rise would result. Currently, the prognosis is a 30% chance of a 20cm ocean level increase. More than 145 million people would be affected by a 1m (3.2 feet) sea-level rise and 870,000 square miles (2.2million square kilometers) of land flooded.
Trevor Williams is a University of Victoria Mechanical Engineering PhD candidate specialising in renewable energy, power grid modelling and plug-in hybrid electric vehicles. He has a bachelors in Aeronautical Engineering, a Masters in Management Science and over 23 years international experience in the space industry, having worked on Earth observation and telecommunications satellites.
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