When the ice melts…

The annual melting of arctic sea reaches its maximum extent in September. This year the melting has been roughly similar to 2007, the greatest extent of melting since humans evolved as a separate species. Click for a larger Image. Data from NSIDC

The annual melting of arctic sea reaches its maximum extent in September. This year the melting has been roughly similar to 2007, the greatest extent of melting since humans evolved as a separate species. Click for a larger Image. Data from NSIDC

As we near the end of summer in the northern hemisphere, the annual melting of the free-floating sea ice is reaching its maximum extent. Soon the temperatures will fall, the ice will re-form, and another winter freeze will commence. The annual melting has been the subject of satellite observation for more than 30 years and there is no doubt that the extent of the summer melting is increasing.

The data from the US National Snow and Ice Data Centre indicate that this year will probably see the greatest extent of summer melting ever seen since humans evolved as a separate species around one million years ago. Compared to 1979, this summer has witnessed the melting of an additional  2 million square kilometres of sea ice. Just to repeat that: two MILLION square kilometres! This is an area of roughly one thousand miles by one thousand miles. It is colossal.

As a specialist in temperature measurement, I am familiar with the use of ‘temperature fixed-points’ for calibrating thermometers. Even when heated, a mixture of ice and water does not increase in temperature, but instead maintains a stable temperature close to 0 ºC until all the ice has melted. In this sense, the arctic ocean in summer forms a gigantic, planetary-scale  fixed point. But when all the ice has melted, heating the liquid causes a temperature rise. And climatalogically, should the summer ever see the complete melting of arctic sea ice – in perhaps as little as 50 to 100 years according to current trends – we can expect the temperature of the region to begin to rise: no longer will an ice-water mixture stabilise the regional temperature.

The gob-smacking magnitude of ‘ice events’  – even on a smaller scale – is evident in this BBC story about the area left by the Peterman Glacier when it broke off from Greenland last year. It is still a major hazard to shipping around Newfoundland with a web page tracking it constantly and this video gives some idea of the scale of just one of the iceberg fragments.

And is all this due to anthropogenic global warming? Well I don’t know, and neither does anyone else. But it is a distinct possibility that we have played a part.

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3 Responses to “When the ice melts…”

  1. Andrew Keith Says:

    “This is an area of roughly one thousand miles by one thousand miles” – wouldn’t 2 million sq. km be two thousand miles by one thousand miles?

    Great blog by the way! Really enjoy reading it…

    • protonsforbreakfast Says:

      No. I sneakily converted (roughly) kilometers to miles.
      2million square kilometres is roughly a square 1414 kilometres on each side
      1414 kilometres is a little less than 1609 kilometres which 1000 miles
      Thank you for the kind words: massive backlog of stuff to write but just too busy at the moment!

      M

  2. Andrew Keith Says:

    Good point! For some reason I failed to notice the change of units. D’oh!

    Enjoyed your article about clouds. I’ve also become a bit of a cloud spotter recently. Not sure my wife gets it though!

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