Posts Tagged ‘Sea Ice’


Good Arctic sea ice pic and vid

28 September 2012

I’ve already blogged about the record Arctic sea ice melt. The following picture and video further illustrate the point. This graphic from the Australian Conservation Foundation shows what the Arctic melt would look like if Australia was melting:

Note that Arctic sea ice volume has declined even more dramatically, with four-fifths disappearing in the 34-year record.

This video from The Yale Forum on Climate Change & The Media also explains it well:


Arctic sea ice minimum: A planetary emergency

21 September 2012

The news that Arctic sea ice is in meltdown is being treated as merely one news item among many, even though it threatens to set off a chain of tipping points affecting all of humanity and life on Earth. I’m reminded of how the iceberg warnings sent to the Titanic by other ships were interspersed with passenger messages, and the final and most urgent warning was not considered important enough to deliver to the captain. In 1912 it was the presence of Arctic ice that failed to sink in; in 2012 it is the absence thereof; but the lack of needed attention is the same.

After a spectacular melt season, the Arctic sea ice finally appears to have reached its annual minimum on 16 September. In a horrible milestone, the ice extent shrank to just 3.4 million square km, which is three-quarters of a million square km (or 18%) below the 2007 record low broken in late August, and less than half of the 1980s average. (Note that sea ice extent includes areas with only partial ice cover; actual sea ice area got as low as 2.2 million square km.)

Source: International Arctic Research Center

The ice has retreated so far as to make the Arctic Ocean circumnavigable:

Source: National Snow & Ice Data Center (NSIDC) Read the rest of this entry ?


Arctic sea ice in a death spiral

29 August 2012

Source: International Arctic Research Center

As Australian politicians fiddle with the details of an extremely insufficient climate change policy, I’ve been watching Arctic sea ice news with increasing dismay. Summer sea ice in the Arctic is fast melting away, accelerated by amplifying feedbacks in what has been called a “death spiral”. The disappearance of Arctic summer sea ice is a key tipping point.

Sea ice floats on the ocean surface and is not to be confused with ice sheets on land. Arctic sea ice grows and shrinks seasonally, with an annual minimum in September. This year, eight independent datasets show we’ve already reached record low sea ice cover in the last week or so, with still weeks to go before the annual minimum.

In the IJIS Arctic sea ice extent dataset (pictured above), the previous record was 4.3 million square km on 24 September 2007 (with the 2011 minimum not far behind). This year we’re only up to 29 August, yet extent has already plummeted to 3.9 million square km. As if that’s not astonishing enough, the ice continues to shrink by 100,000 square km per day. Normally at this time of year, melting slows down as the melt season draws to a close – but this time it seems to be still accelerating, which is unprecedented in decades of observations. Nobody can predict what will happen next. Read the rest of this entry ?


Titanic and Global Warming

15 April 2012

After the RMS Titanic’s collision with an iceberg a century ago today, the passengers did not believe the ocean liner would sink. The ship was so gargantuan and stably designed it showed few outward signs of being in imminent danger, and took 2 hours and 40 minutes to sink. But sink it did. The Earth’s climate is rather like the Titanic: an enormous beast that is deceptively stable and slow to respond to disturbances.

(Source: Wikipedia.)

The parallels between global warming and the Titanic disaster begin before the collision, with the failure to heed iceberg warnings. If you’ll forgive me for quoting Wikipedia:

The North Atlantic liners prioritised time-keeping above all other considerations, sticking rigidly to a schedule that would guarantee their arrival at an advertised time. They were constantly driven at close to their full speed, treating hazard warnings as advisories rather than calls to action. It was widely believed that ice posed little risk […] Titanic‘s future captain, Edward Smith, declared in an interview that he could not “imagine any condition which would cause a ship to founder. Modern shipbuilding has gone beyond that.” Read the rest of this entry ?


Christy Crock: Do the observations match the models?

21 April 2011

I wrote this post for Skeptical Science.

At the recent US House of Representatives Committee on Science Space and Technology climate hearing, the Republicans called Dr. John Christy as an expert witness testifying against the global warming consensus. Unfortunately, Christy spent his time repeating a long list of climate myths, including the common contrarian refrain that “climate model output does not match up to the real world”. Let’s examine this claim.

A tale of three climate indicators

Surface temperature observations are well within the range of model projections:

Observed global temperatures since 1980 compared to IPCC AR4 model projections Read the rest of this entry ?


A basic overview of melting ice around the globe

17 February 2011

I wrote this post for Skeptical Science as a basic rebuttal of the argument “Ice isn’t melting”.

Contrary to contrarian claims, ice is melting at accelerating rates in the Arctic, Antarctica, Greenland, and glaciers all over the world. Arctic sea ice has shrunk by an area equal to Western Australia, and could be all gone in a decade.

Ice sheets are beginning to shrink

An ice sheet is a huge layer of land ice. The only ice sheets are in Antarctica and Greenland.

The Greenland ice sheet is losing mass at an accelerating rate. In recent years the ice loss has spread from the south coast around to the northwest.

Read the rest of this entry ?


Monckton Myth: Global Sea Ice

22 January 2011

I wrote this post for Skeptical Science as part of an ongoing series looking at the arguments made by Christopher Monckton against climate science.

This post examines Monckton’s arguments about global sea ice. Monckton claims:

[T]he global sea ice record shows virtually no change throughout the past 30 years, because the quite rapid loss of Arctic sea ice since the satellites were watching has been matched by a near-equally rapid gain of Antarctic sea ice.

Global Sea Ice Is Decreasing

Have Arctic ice losses truly been balanced by Antarctic gains? The first point to clarify is that we are talking about floating sea ice, not to be confused with land ice. Land ice at both poles and in glaciers around the world is sliding into the ocean at an accelerating rate. This net loss of land ice is contributing to sea level rise.

However, Monckton is clearly referring to sea ice. The rapid decline of Arctic sea ice has indeed coincided with an increase in Antarctic sea ice. But do these two opposite trends cancel out as Monckton suggests? In reality, the upward Antarctic trend is only slight compared to the plummeting Arctic trend. Tamino has crunched the numbers and found the Arctic trend is in fact more than three times faster than the Antarctic one. The net result is a statistically significant global decrease of more than a million km2 – would you agree with Monckton that this is “virtually no change”?

Figure 1: Global sea ice extent since 1979. (Image source: Tamino. Data is from US National Snow and Ice Data Center.) Read the rest of this entry ?


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