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NSIDC: Arctic “melt season in high gear”

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"NSIDC: Arctic “melt season in high gear”"

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monthly extent plot

The National Snow and Ice Data Center has a July 6 update on Arctic ice melt:

The Arctic is now in the midst of the summer melt season. Through most of June, ice extent tracked below the 1979 to 2000 average, and slightly above the levels recorded during June 2007. Warm temperatures and southerly winds led to quickly declining ice concentration in some regions, such as the Laptev Sea….

Compared to previous Junes, ice extent in June 2009 was extremely close to the last two years, falling within 30,000 square kilometers (12,000 square miles) of the June extent in 2007 and 2008. The long-term trend indicates a decline of 3.3% per decade, an average of 40,100 square kilometers (15,500 square miles) of ice per year.

Will we see a record minimum this year?

time series

The warmth in the Laptev Sea is consistent with a pattern of southerly winds in these areas, which can be linked to the area of low atmospheric pressure centered just north of Novaya Zemlya Island. Note also the strong high-pressure cell (an anticyclone) over the northern Beaufort Sea.

This contrast between high and low pressure is broadly similar to the atmospheric circulation pattern that set up in 2007. In 2007, that pattern contributed to a significantly accelerated decline in ice extent during July, and a record minimum low in September. Will the same acceleration in ice melt occur this year? If so, a new record low minimum extent becomes more likely. So far, an acceleration has not been observed. As July progresses, the Arctic sun gets lower on the horizon, incoming solar energy decreases, and the chances of such a rapid decline become less likely.

Bottom Line:  Too early to say.

I would note that we are only getting a two-dimensional look at sea ice extent.  From a three-dimensional perspective, 2008 was probably the record low Arctic ice volume (see NSIDC stunner: Arctic ice at “Likely Record-Low Volume”), and we will likely be close to that this year.

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6 Responses to NSIDC: Arctic “melt season in high gear”

  1. paulm says:

    ‘The Greenland Ice Sheet Is an Awakening Giant’
    http://www.spiegel.de/international/world/0,1518,634629,00.html

    …we are in a better position right now. New estimates that we are about to finalize suggest a potential sea-level rise from the Greenland ice sheet that could be 0.35 meters (14 inches) over the next century.

    As a scientist it is, nevertheless, interesting to see that the politicians are trying to figure out what would be feasible politically. Currently, trying to cap global warming at two degrees is something that they can seemingly sell to the public. But as a scientist I have to really stress that two degrees is an absolute maximum. It is not something to be negotiated, like 2.7 or 2.5 degrees. We are at the very maximum already, I believe.

  2. Is there a single chart that combines data from a few more years, shows simple extent coverage, marks the nadir for each year, and shows ice volume?

  3. dhogaza says:

    Richard Pauli:

    This graph from cryosphere today shows seasonal (three-month) data, and you can see that winter extent is declining more slowly than the summer minimum. When you consider that the sea freezes right up to land in much of the arctic every year, you can understand why – it will take a vast amount of warming for there to be open water next to much of the northern coasts of eurasia and north america. We’re not close to that, yet. Thus the emphasis in summer minimum (you may’ve already known this, if so, my apologies).

    This one, also from cryosphere today, shows the seasonal variation from 1979, so by comparing the bottom of each cycle you can get a sense of the trend in minimum extent.

  4. Wonhyo says:

    The deniers might point to the graph and say June sea ice extent has been increasing since the last one and three years. A neutral party might say June sea ice extent has declined gradually by 8% since 1979. A true climate scientist would ask to see a plot of see ice volume over the same time period.

    I agree with Paulm’s first comment: It’s dangerous to try to negotiate with natural limits. The political process (including Waxman-Markey) threatens to produce too little, too late, as long as we approach climate change with political motivations.

    As a society, we must recognize the fundamental needs of climate mitigation and adapt the political process to meet those needs, not vice versa.

  5. Greg Robie says:

    Serreze and company have been very disciplined to limit what they post each month to facts. While such is good science, it is less than informative relative to the “smack-down” affect of what can pass as being a “good” blog writing style/content. That aside, even with the slow start, I expected a much faster melt off this year than what has happened (so far).

    When the melt crossed and then uncrossed the 2007 record decline, I added a few more bookmarks to my “Arctic” folder on my browser’s bookmark bar that I check daily. While I would value the following being confirmed or refuted, it looks to me like the cloud cover has increased, that the massive quantity of single year ice may be behaving differently, and over the last two weeks or so, the jet stream has gone nuts.

    With a recent study suggesting that an increase in low clouds are a positive feedback (and I can not tell whether the clouds I am seeing are high or low clouds), the slower rate has puzzled me. The microwave data incorporated into the NSIDC report for June confirmed the visuals I have been following of the Beauford Sea I look at (and my speculation that all the 1st year ice may be leading to different melt dynamics stems from). Whatever, there are large areas in the Beauford Sea that have been thinning out and, like the Laptev Sea, seem to be poised to add (but for cloud cover and reorganizing air currents at 300 mb), quickly and extensively, to the ice extent decline. The craziness of the jet stream (besides giving the northeast easterlies) has led to rapid declines I’ve been anticipating in the extent in Hudson Bay and the Baffin Sea the last couple of days.

    Anyway, I am not sure the bottom line is that it is too early to tell. I think the climate in the Arctic, as predicted, is changing first/the most. If I were a betting person, the 50/50 chance for an ice free North Pole (as in physical location) Serreze got into trouble talking about last year is a statement he will be vindicated on and is still a good bet The high that is mentioned, if it hangs in there, the bet is a no brainer. If whatever is happening at 300 mb continues as it has been, the northwest passage will open way ahead of last year . . . and the slugs will do well in my garden in NY with all the rain we will continue to getting.