Antarctic ice tipping point or irregularity

Summer sea ice in Antarctica dropped significantly last year and remains low. Scientists say time is needed (years) to determine if it is a one-off irregularity, or if a tipping point  has been passed and Antarctica is catching up with Arctic warming.

AntarcticSeaIce2017

Source: http://nsidc.org/arcticseaicenews/

2017 (blue) is similar to an unusual low on 2002 (green), both well below median.

Newshub: ‘Daunting’ Antarctic sea ice plummet could be tipping point

A dramatic drop in the amount of sea ice around Antarctica has scientists wondering if the continent has hit a tipping point.

There has been a record 30 percent decrease in the total amount of sea ice, and this summer it’s disappearing from the Ross Sea at a rate not seen in more than 30 years.

The rapidly changing conditions are having a major impact on this year’s scientific research at Scott Base, with scientists describing the changes as “unusual”, “unprecedented” and “daunting”.

One of the affected scientists is Antarctic oceanographer Dr Natalie Robinson, who studies sea ice and what lies beneath it.

“We had about 200km of sea ice to play with last year, but this year we’re down to about 25-30km, so it’s certainly a very different ball game,” she told Newshub.

The Antarctic sea ice growth in winter and melt in summer is the biggest annual change on the planet. Dr Robinson describes it as the heartbeat or pulse of Earth, and it affects everybody because it drives global weather.

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During November the sea ice edge is usually around 100km further north of where it is this year. For it to have broken out this early is a significant change and it’s causing alarms bells to ring.

“This is my 30th trip into the Southern Ocean and Antarctica,” climate scientist Professor Gary Wilson told Newshub.

“Of all the visits I’ve made down here, we haven’t seen the sea ice break out as much as it has this early.”

The sea ice is not only melting ahead of schedule, there’s a lot less of it to begin with. Last year there was 30 percent less ice – a drop of around 1 million square kilometres.

Climate scientists believe Antarctica may have hit a tipping point.

“This could be the moment that Antarctica is catching up with the Arctic,” Prof Wilson said.

Climate scientists will be watching closely over the next few years to establish whether this is a one-off event, or the moment Antarctica began to succumb to a rapidly warming planet.

A problem with monitoring the climate is it can take years to determine whether changes are normal fluctuations or signifying trends – and trends are unlikely to be smooth progressions.

Global sea ice at record low

 

They keep putting out stories like this.

New Scientist: Global sea ice is at lowest level ever recorded

It’s a new low point. The area of the world’s oceans covered by floating sea ice is the smallest recorded since satellite monitoring began in the 1970s. That means it is also probably the lowest it has been for thousands of years.

The latest observations from the US National Snow & Ice Data Center in Boulder, Colorado, show how the ice extent has fallen to a new low this year (bright red trace in the graph below).

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In the Arctic, the low in sea ice coverage is a result of both global warming and unusual weather events probably influenced by global warming.

But in the Antarctic, the current low in seasonal sea ice could just be a result of natural variability.

The extent of Arctic sea ice should be growing rapidly during the northern hemisphere winter. But not only has the Arctic been warming rapidly, this winter repeated incursions of warm air have pushed temperatures even further above average.

Yep, there’s been cold weather in the US and European winters, and we have had an unusually cool summer here, but these are regional and short term variations. In contrast to here Australia has been hot.

And at the bottom of the world there is news of another large ice shelf crack developing: British Antarctic Survey abandons polar base as worrying crack grows in ice

Scientists at the British Antarctic Survey are abandoning their research station for the first time ever this winter after a new worrying crack developed in the ice sheet.

The renowned Halley VI ice base, from which the hole in the ozone layer was first detected, was already scheduled to be relocated 14 miles across the Brunt Ice Shelf because of an encroaching fissure in the ice.

But a new crack has been steadily growing to the north of the base, and computer modelling suggests that it could cause a large iceberg to calve away from the sheet, which could destabalise the area.

It is the latest problem to beset the base.   In 2012, satellite monitoring of the ice shelf revealed the first signs of movement in the chasm that had lain dormant for at least 35 years and, by 2013, it began opening at an alarming pace of one mile per year.  If the base does not move, it could be in danger of tumbling into the chasm by 2020.

To make matters more time critical, in October, a new crack emerged 10 miles to the north of the research station across the route sometimes used to resupply the base.

The base is crucial to studies into global issues such as the impact of extreme space weather events, climate change, and atmospheric phenomena.

That’s a bit ironic, whether the accelerating cracking is coincidental or not.