Saturday, May 16, 2015

Melting Antarctic Ice and Sea Level Rise (Video)

Antarctica from Kalle Ljung on Vimeo.

This recently shot movie reveals the beauty of Antarctic ice and highlights what we stand to lose if we do not succeed in curbing climate change causing emissions. Global warming is melting the ice in Antarctica and this could cause flooding on a massive scale. Currently 159 billion tonnes of ice is melting each year in the Antarctic and the seas are rising by one meter per century. However melting ice and sea level rise appears to be radically accelerating. Studies show that the melting of Antarctic ice three million years ago led to sea level rises of at least 55 feet. If this happens today, places currently inhabited by hundreds of millions of people would be under water and some nations would disappear altogether. Beyond the catastrophic impacts of flooding every inch of sea level rise dramatically increases the destruction caused by storm surges.

Earlier this week, scientists observed a massive crack in Larsen C ice shelf corroborating the finding that it is disintegrating at a rapid pace. Scientists from the British Antarctic Survey and several other research centers say this could pose an “imminent risk” to its stability.

As reported by the Washington post, NASA says that the Antarctic ice shelf could collapse by 2020. NASA has found that the last section of Antarctica's Larsen B Ice Shelf is likely to disintegrate before the end of the decade. In this new study published in Earth and Planetary Science Letters, researchers with NASA’s Jet Propulsion Laboratory and the University of California at Irvine say that the Larsen B shelf now faces its “approaching demise" and “is likely to disintegrate completely before the end of the decade.”

The land-based glaciers behind the shelf are also sliding faster toward the sea. The U.S. Geological Survey estimates that together all the glaciers of the Antarctic peninsula region could conceivably contribute up to 1.5 feet of global sea-level rise. If the great ice sheets of Greenland, West Antarctica and East Antarctica melt this will result in a much greater sea level rise.

The amount of melting ice in Antarctica make it ground zero for climate change. So much ice is melting in the Antarctic that it is changing the Earth's gravitational field. As reviewed in the Guardian, IPCC research indicates that between 1993 and 2010 the seas have risen by about 1.2 inches a year, what is even more disturbing is that this number is accelerating. About a third of that annual rise comes from the warming oceans because warmer ocean water takes up more space. The second biggest driver is the melting of glaciers around the world (outside of Greenland and Antarctica).

The melting of ice sheets in Greenland and Antarctica currently account for only about one sixth of the observed sea level rise, but as that melting accelerates they could account for a much more substantial portion.

A recent study shows that the ice in the Western Antarctic continues to melt. A May 2014 study signaled that the ice in Antarctic is in "rapid retreat" and a study published one month later used satellite data to confirm the accelerated melting of ice. Another study showed how the melting Antarctic ice during the Pliocene three million years ago led to a 17 meters or 55 foot sea level increase.

Although there is a fair degree of uncertainty in the model the scientists who did the research say that once a threshold is passed, the ice may melt very quickly. The Pliocene is interesting because levels of carbon dioxide in the atmosphere were similar to today (400 parts per million in the atmosphere right now), with temperatures between 2C and 3C above preindustrial times.

According to the computer model used in the study it took 100 years for the West Antarctic ice sheet to raise sea levels by about three meters. The East Antarctic ice sheet contributed about 14 meters of sea level rise according to the model.

One of the leading experts on sea level rise Australian scientist Dr John Church, the co-coordinating lead author of the relevant chapter in the latest IPCC report found that without cuts to greenhouse gas emissions, in less than 70 years, sea levels could rise as high as one meter from where they were a decade ago.

It may already be too late to stop the Antarctic ice melt. Some Antarctic glaciers have already passed the point of no return.

Church told the Guardian that If we exceed global temperature increase thresholds (somewhere between 1 and 4 degrees Celsius) this would commit the world to rising sea levels for thousands of years. Church also made the following ominous statement: "Since the IPCC report, studies have shown that this process is now happening. We have triggered something that is potentially unstoppable,"

Church said without “urgent mitigation” of greenhouse gas emissions “we commit the world to sea level rises for millennia”. Church went on to say:
"It is the decisions that we are making now that determine if we cross those thresholds. In those IPCC projections, when you look at the last two decades of this century, the rate of sea level rise is up at one metre per century. That is a rapid rise that can’t be turned around. That’s a commitment we are making for future generations."

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