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Is global warming near a tipping point in Greenland?

THIS STUFF raises the specter of higher sea levels and flooded coastal areas:

Recent findings suggest climate change in Greenland may be approaching a tipping point, beyond which amplifying feedbacks could lead (probably over centuries) to complete melting of the ice sheet, raising sea level by about 7 meters.

In June, a team of glaciologists led by Jason Box predicted that we would see melting across 100% of the ice sheet’s surface area in summer within a decade. They drew that conclusion from data on the Greenland ice sheet’s surface reflectivity, or “albedo”, showing the surface has gotten darker over the last 12 years. A darker surface absorbs more heat, leading to more melting, causing albedo to decrease further, and so on in a vicious circle.

The ice naturally gets less reflective in summer because the shape of the snowflakes changes and meltwater reveals impurities beneath the surface, but in 2012 Greenland has become much darker than in previous summers. This is occurring particularly at high elevations, which were previously too cold to melt and indeed had gained ice from increasing snowfall. This month, at the height of the melt season, Greenland’s albedo has fallen far off the charts.

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5 Comments

  1. The NASA press release said that the event happens about every 150 years, and was right on schedule.

    Obviously it has nothing to do with global warming or tipping points.

  2. Steve Goddard: Your flat-out claim that this event “has nothing to do with global warming or tipping points” is NOT supported by the NASA press release, despite your suggestion to the contrary.

    Read this passage from that release:

    “Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time,” says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data. “But if we continue to observe melting events like this in upcoming years, it will be worrisome.”

  3. I expected this post to further convince me about global warming.

    In fact it seems to do the opposite.

    Apparently the melting event in Greenland is right on time. Given the 150 year gap between such events , and all of the industrial revolution turmoil that has happened in between, the fact that this event is on time suggests a relatively stable homeostasis of the normal ebbs a flows of temperature.

  4. doc: Check out the comment just above yours.

  5. I did check it out, that’s why I posted my comment. The summary of her quote is “things are going just as expected but if that changes then I will be worried.”

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