The Arctic ice death spiral - and the Antarctic

Here is a somewhat more optimistic view of the Arctic death spiral than that of Guy McPherson or the Arctic Methane Energency Group, justaposed with the idiotic statements of arch-denier, Christopher Monkton.

Also some emphasis on the Antarctic, of interest to those in the Southern Hemisphere.

For what it's worth, if I saw Monkton I'd probably (like David Suzuki) retreat quickly, although not for the reasons he gives.

Arctic Sea Ice: The Death Spiral Continues

Here is the interview with Lord Monkton that is referred to -

And here is the answer to his claim that Antarctic ice cover is increasing -

Antarctic ice melting from below, reveals satellite (+video)

Antarctica's ice shelves are being melted away by warm ocean currents underneath, shows data collected from a NASA satellite.

Warm ocean currents attacking the underside of ice shelves are the dominant cause of recent ice loss from Antarctica. This animation shows the circulation of ocean currents around the western Antarctic ice shelves. The shelves are indicated by the rainbow color; red is thicker (greater than 550 meters), while blue is thinner (less than 200 meters).

Christian Science Monitor,

26 April, 2013

Data collected from a NASA ice-watching satellite reveal that the vast ice shelves extending from the shores of  western Antarctica are being eaten away from underneath by ocean currents, which have been growing warmer even faster than the air above.

The animation above shows the circulation of ocean currents around the western Antarctic ice shelves. The shelf thickness is indicated by the color; red is thicker (greater than 550 meters), while blue is thinner (less than 200 meters).

Launched in January 2003, NASA’s ICESat (Ice, Cloud and land Elevation Satellite) studied the changing mass and thickness of Antarctica’s ice from its location in polar orbit. An international research team used over 4.5 million surface height measurements collected by ICESat’s GLAS (Geoscience Laser Altimeter System) instrument from Oct. 2005 to 2008. They concluded that 20 of the 54 shelves studied — nearly half — were losing thickness from underneath.

Most of the melting ice shelves are located in west Antarctica, where the flow of inland glaciers to the sea has also been accelerating — an effect that can be compounded by thinning ice shelves which, when grounded to the offshore seabed, serve as dams to hold glaciers back.

Melting of ice by ocean currents can occur even when air temperature remains cold, maintaining a steady process of ice loss — and eventually increased sea level rise.

“We can lose an awful lot of ice to the sea without ever having summers warm enough to make the snow on top of the glaciers melt,” said Hamish Pritchard of the British Antarctic Survey in Cambridge and the study’s lead author . “The oceans can do all the work from below.”

The study also found that Antarctica’s winds are shifting in response to climate change.

“This has affected the strength and direction of ocean currents,” Pritchard said. “As a result warm water is funnelled beneath the floating ice. These studies and our new results suggest Antarctica’s glaciers are responding rapidly to a changing climate.”

ICESat completed operations in 2010 and was decommissioned in August of that year. Its successor ICESat-2 is anticipated to launch in 2016.

Read more on NASA’s news release here.

Melting in Antarctica is worst in 1,000 years

The amount of ice melting on the Antarctic Peninsula has increased dramatically in recent decades.

Al-Jazeera,

14 April, 2013

For the first time, scientists have managed to demonstrate that ten times more ice melts in the summer months on the Antarctic Peninsula now than it did 600 years ago.

Antarctic, with the Antarctic Peninsula highlighted. [NASA]

The Antarctic Peninsula is the biggest and most prominent peninsula in Antarctica. It consists of a rugged mountain chain, which rises more than 2000 m high.

Unlike the majority of the continent, the ice on the peninsula experiences a degree of melting every summer. Over recent decades the amount of ice which has melted has been increasing.

It has been known for some time that temperatures across the Antarctic Peninsula have risen dramatically. Over the past fifty years there has been an increase of 2.8C, making this the most rapidly warming region in the Southern Hemisphere. This is over five times the global average and comparable to rapidly warming regions of the Arctic.

At the same time, around 25,000 km2 of ice have been lost from ten floating ice shelves on the Antarctic Peninsula. This is particularly significant as it takes a long time to replenish snow and ice in this part of the world.

With under 250 mm of precipitation per year, Antarctica is officially classed as a desert. In fact, some parts of the continent haven’t seen any rain or snow for many years. Across the Antarctic Peninsula, the snow and ice simply melts and refreezes. Currently the ice that is lost to melting far exceeds that which is replenished in a year.

The latest research, a joint project by the Australian National University and the British Antarctic Survery and published in Nature Geoscience, looks at a 364 m ice core, which was extracted from the northern tip of the peninsula. Visible layers of this tube of ice show where the ice melted, then refroze. By measuring the thickness of the layers and analysing the gases contained in the ice, researchers were able to determine the changes in temperatures in the region over the last 1,000 years.

The ice core demonstrated that the current level of melting was unprecedented in the last 1,000 years, and ten times more than it was 600 years ago.

The climate of Antarctica is hugely complex. Although there are record levels of glacier and ice melting, there also appears to be an increase in the sea ice in the surrounding waters.

Just seven months ago satellites captured images of more ice floating around the continent than at any other time in history.

The increase in sea ice is thought to be caused by the increased amounts of melting ice. This melted ice runs into the sea, but does not mix with the water already in the ocean. Instead the water forms a separate, colder, layer on the surface of the ocean. This can protect sea ice from coming into contact with the warmer seas below and therefore prevent it melting.

It is also thought that a change in wind direction could have increased the extent of sea ice. Winds can both physically moving the ice, and can cause the sea surface to warm or cool. The increase in sea ice is not uniform around the Antarctic coast line, therefore the winds are also likely to have had some effect.

With the complex climate of Antarctica, and the uncertainty of the future of the climate, it is difficult to predict what this latest study means for the continent.

It is believed that the continent will continue to warm rapidly, particularly in summer, increasing the vulnerability of the delicate ecosystem of the continent.

The global significance of this is difficult to assess. However, the warming of the Antarctic Peninsula is amongst the highest seen anywhere on Earth in recent times, and is a reminder of the rationality of climate change that can be expected in the future.