“Steepest slope ever.”
By Steven Goddard
We have been hearing a lot about how the decline in Arctic ice is following the “steepest slope ever.” The point is largely meaningless, but we can have some fun with it. The Bremen Arctic/Antarctic maps are superimposed above, showing that ice in the Antarctic is at a record high and growing at the “steepest slope ever.” You will also note that most of the world’s sea ice is located in the Antarctic. But those are inconvenient truths when trying to frighten people into believing that “the polar ice caps are melting.”
There are several favorite lines of defense when trying to rationalize away the record Antarctic ice.
1. It is the Ozone Hole – which is also the fault of evil, American SUV drivers. That is a nice guilt trip, but sadly the Ozone Hole doesn’t form until August and is gone by December. Strike one.
The next one is to point out that some regions of the west side of the tiny Antarctic Peninsula have been warming. Never mind that the Antarctic Peninsula is an active volcanic ridge, and that the waters around it have not shown any significant warming. Strike two.
UAH shows Antarctica cooling slightly over the last 30 years.
The third favorite line of defense is to argue that “we expected Antarctica to warm more slowly because of the mass of the southern oceans.” Nice try – “slower warming” is not the same as “cooling.” Strike three.
(The AGW view of Antarctica is every bit as irrational as FIFA’s stand that not having instant replays somehow helps the referees’ reputations.)
On to the Arctic. First graph is a JAXA comparison of 2006, 2007 and 2010. Note that 2006 and 2007 were nearly identical, until early July. The main difference between 2006 (second highest in the JAXA record) and 2007 (lowest in the JAXA record) was that strong southerly winds compacted and melted the ice in 2007. As you can see below, the summer extent numbers are nearly meaningless before July/August. So far, 2010 is tracking very closely with both 2006 and 2007, and it appears the three will intersect in about a week.
Let’s take a closer look at the mechanisms using the PIPS ice and wind data. If we watch the movement of Arctic ice during the summer, we can see that when the winds blow away from the pole (i.e. from the north) the ice expands. When the wind blows from the south, the ice contracts. Some summers, the winds alternate between north and south, and the ice extent changes less during the summer – like in 2000 below.
Other years, like 2007, the summer winds blew consistently from the south, causing the ice to melt at a faster pace and compress towards the north.
So basically, it is weather (wind) rather than climate which controls the summer minimum. Of course, it is harder to compress and melt thick ice than thin ice – so the thickness of the ice is important. It is too early to determine if 2010 will see winds like 2007, or if summer winds this year will be more like 2006.
No one has demonstrated much skill at forecasting winds six weeks in the future, so it is really anybody’s guess what wil happen this summer. Before August arrives, the pattern should be clear.
The video below shows ice movement near Barrow, AK over the past 10 days.
The winds were blowing strongly and contracting the ice edge until the last few days, when they died down. Over the past two or three days, the ice edge has not moved very much.
Over the last week, almost all of the ice loss in the Arctic has been in the Hudson Bay, as seen in the modified NSIDC image below in red. The Hudson Bay is normally almost ice free in September, so the recent losses are are almost meaningless with respect to the summer minimum.
The modified NSIDCimage below shows ice loss since early April. All of the areas shown in red are normally ice free in September.
The modified NSIDC image below is a comparison of 2010 vs 2007. Areas of red had more ice in 2007. Areas of green have more ice in 2010.
‘
The modified NSIDC image below shows the current deficiencies in red. Again, all of those areas are normally ice free in September, so they don’t tell us much about the summer minimum.
Below is my forecast for the remainder of the summer.
But it all depends on the wind.
From the 9th century to the 13th century almost no ice was reported there. This was the period- of Norse colonization of’ Iceland and Greenland. Then, conditions worsened and the Norse colonies declined. After the Little Ice Age of 1650 to 1840 the ice began to vanish near Iceland and had almost disappeared when the trend re versed, disastrously crippling Icelandic fisheries last year.
The thick ice that has for ages covered the Arctic Ocean at the pole has turned to water, recent visitors there reported yesterday. At least for the time being, an ice-free patch of ocean about a mile wide has opened at the very top of the world, something that has presumably never before been seen by humans and is more evidence that global warming may be real and already affecting climate. The last time scientists can be certain the pole was awash in water was more than 50 million years ago.
Is it possible that the IPCC is trying to rewrite the history books?
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SouthAmericanGirls says: June 29, 2010 at 6:29 pm
“I wish so much that a place like WUWT existed for macroeconomics “science” since macroeconomics is among the worst pseudosciences that exist.”
“Macroeconomics is one of the most corrupt of the pseudosciences, it would be so great that honest macroeconomists visited more often places like WUWT to LEARN how you actually do science.”
For now we need to focus on our time and energy on debunking the Catastrophic Anthropogenic Global Warming Narrative, but in the future we should be able to leverage the WUWT model to help drive forward human knowledge and understanding in a wide array of areas. And I may also know a thing or two about economics…
Gavin says:
June 30, 2010 at 2:28 pm
What do you think of the 7-day forecast for this town on the Russian arctic coast?
Yawn.
stevengoddard says:
June 28, 2010 at 10:16 pm
In three days, the slope of the Arctic extent graph will begin to drop off.
Mark it on your calendar.
…………………………………………………………………………………………………………………
A day early:
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
That’s exactly how I feel about your posts Amino….a large YAWN. Let me know when you actually have some science to talk about.
jeff brown
It’s become pretty clear to me that people have differing definitions of science. 🙂
Gavin says:
June 30, 2010 at 2:28 pm
What do you think of the 7-day forecast for this town on the Russian arctic coast?
More importantly, what do you think of ClimateGate?
Amino Acids in Meteorites says:
June 30, 2010 at 11:34 pm
Gavin says:
June 30, 2010 at 2:28 pm
“What do you think of the 7-day forecast for this town on the Russian arctic coast?”
More importantly, what do you think of ClimateGate?
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What’s your point, apart from avoiding the issue raised. Inconvenient truth? Often enough, when scrutinising this blog, weather events are used to ‘prove’ that AGW is not happening. Gavin pointed you at temperatores rising to 33C in Siberia. You just exposed the point he made. Should fit well with the latest WUWT topic, weather v climate.
Temperatures and temp anomalies for Arctic and Antarctic for June 16-28:
Arctic temp
http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/comp.day.pl?var=Air+Temperature&level=Surface&iy%5B1%5D=&im%5B1%5D=&id%5B1%5D=&iy%5B2%5D=&im%5B2%5D=&id%5B2%5D=&iy%5B3%5D=&im%5B3%5D=&id%5B3%5D=&iy%5B4%5D=&im%5B4%5D=&id%5B4%5D=&iy%5B5%5D=&im%5B5%5D=&id%5B5%5D=&iy%5B6%5D=&im%5B6%5D=&id%5B6%5D=&iy%5B7%5D=&im%5B7%5D=&id%5B7%5D=&iy%5B8%5D=&im%5B8%5D=&id%5B8%5D=&iy%5B9%5D=&im%5B9%5D=&id%5B9%5D=&iy%5B10%5D=&im%5B10%5D=&id%5B10%5D=&iy%5B11%5D=&im%5B11%5D=&id%5B11%5D=&iy%5B12%5D=&im%5B12%5D=&id%5B12%5D=&iy%5B13%5D=&im%5B13%5D=&id%5B13%5D=&iy%5B14%5D=&im%5B14%5D=&id%5B14%5D=&iy%5B15%5D=&im%5B15%5D=&id%5B15%5D=&iy%5B16%5D=&im%5B16%5D=&id%5B16%5D=&iy%5B17%5D=&im%5B17%5D=&id%5B17%5D=&iy%5B18%5D=&im%5B18%5D=&id%5B18%5D=&iy%5B19%5D=&im%5B19%5D=&id%5B19%5D=&iy%5B20%5D=&im%5B20%5D=&id%5B20%5D=&monr1=6&dayr1=16&monr2=6&dayr2=28&iyr%5B1%5D=2010&filenamein=&plotlabel=&lag=0&labelc=Color&labels=Shaded&type=1&scale=&label=0&cint=1&lowr=-3&highr=3&istate=0&proj=Custom&xlat1=55&xlat2=90&xlon1=0&xlon2=360&custproj=Northern+Hemisphere+Polar+Stereographic&level1=1000mb&level2=10mb&Submit=Create+Plot
Arctic temp anomaly
http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/comp.day.pl?var=Air+Temperature&level=Surface&iy%5B1%5D=&im%5B1%5D=&id%5B1%5D=&iy%5B2%5D=&im%5B2%5D=&id%5B2%5D=&iy%5B3%5D=&im%5B3%5D=&id%5B3%5D=&iy%5B4%5D=&im%5B4%5D=&id%5B4%5D=&iy%5B5%5D=&im%5B5%5D=&id%5B5%5D=&iy%5B6%5D=&im%5B6%5D=&id%5B6%5D=&iy%5B7%5D=&im%5B7%5D=&id%5B7%5D=&iy%5B8%5D=&im%5B8%5D=&id%5B8%5D=&iy%5B9%5D=&im%5B9%5D=&id%5B9%5D=&iy%5B10%5D=&im%5B10%5D=&id%5B10%5D=&iy%5B11%5D=&im%5B11%5D=&id%5B11%5D=&iy%5B12%5D=&im%5B12%5D=&id%5B12%5D=&iy%5B13%5D=&im%5B13%5D=&id%5B13%5D=&iy%5B14%5D=&im%5B14%5D=&id%5B14%5D=&iy%5B15%5D=&im%5B15%5D=&id%5B15%5D=&iy%5B16%5D=&im%5B16%5D=&id%5B16%5D=&iy%5B17%5D=&im%5B17%5D=&id%5B17%5D=&iy%5B18%5D=&im%5B18%5D=&id%5B18%5D=&iy%5B19%5D=&im%5B19%5D=&id%5B19%5D=&iy%5B20%5D=&im%5B20%5D=&id%5B20%5D=&monr1=6&dayr1=16&monr2=6&dayr2=28&iyr%5B1%5D=2010&filenamein=&plotlabel=&lag=0&labelc=Color&labels=Shaded&type=2&scale=&label=0&cint=1&lowr=-3&highr=3&istate=0&proj=Custom&xlat1=55&xlat2=90&xlon1=0&xlon2=360&custproj=Northern+Hemisphere+Polar+Stereographic&level1=1000mb&level2=10mb&Submit=Create+Plot
Antarctic temp
http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/comp.day.pl?var=Air+Temperature&level=Surface&iy%5B1%5D=&im%5B1%5D=&id%5B1%5D=&iy%5B2%5D=&im%5B2%5D=&id%5B2%5D=&iy%5B3%5D=&im%5B3%5D=&id%5B3%5D=&iy%5B4%5D=&im%5B4%5D=&id%5B4%5D=&iy%5B5%5D=&im%5B5%5D=&id%5B5%5D=&iy%5B6%5D=&im%5B6%5D=&id%5B6%5D=&iy%5B7%5D=&im%5B7%5D=&id%5B7%5D=&iy%5B8%5D=&im%5B8%5D=&id%5B8%5D=&iy%5B9%5D=&im%5B9%5D=&id%5B9%5D=&iy%5B10%5D=&im%5B10%5D=&id%5B10%5D=&iy%5B11%5D=&im%5B11%5D=&id%5B11%5D=&iy%5B12%5D=&im%5B12%5D=&id%5B12%5D=&iy%5B13%5D=&im%5B13%5D=&id%5B13%5D=&iy%5B14%5D=&im%5B14%5D=&id%5B14%5D=&iy%5B15%5D=&im%5B15%5D=&id%5B15%5D=&iy%5B16%5D=&im%5B16%5D=&id%5B16%5D=&iy%5B17%5D=&im%5B17%5D=&id%5B17%5D=&iy%5B18%5D=&im%5B18%5D=&id%5B18%5D=&iy%5B19%5D=&im%5B19%5D=&id%5B19%5D=&iy%5B20%5D=&im%5B20%5D=&id%5B20%5D=&monr1=6&dayr1=16&monr2=6&dayr2=28&iyr%5B1%5D=2010&filenamein=&plotlabel=&lag=0&labelc=Color&labels=Shaded&type=1&scale=&label=0&cint=&lowr=&highr=&istate=0&proj=Custom&xlat1=-90&xlat2=-55&xlon1=0&xlon2=360&custproj=Southern+Hemisphere+Polar+Stereographic&level1=1000mb&level2=10mb&Submit=Create+Plot
Antarctic temp anomaly
http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/comp.day.pl?var=Air+Temperature&level=Surface&iy%5B1%5D=&im%5B1%5D=&id%5B1%5D=&iy%5B2%5D=&im%5B2%5D=&id%5B2%5D=&iy%5B3%5D=&im%5B3%5D=&id%5B3%5D=&iy%5B4%5D=&im%5B4%5D=&id%5B4%5D=&iy%5B5%5D=&im%5B5%5D=&id%5B5%5D=&iy%5B6%5D=&im%5B6%5D=&id%5B6%5D=&iy%5B7%5D=&im%5B7%5D=&id%5B7%5D=&iy%5B8%5D=&im%5B8%5D=&id%5B8%5D=&iy%5B9%5D=&im%5B9%5D=&id%5B9%5D=&iy%5B10%5D=&im%5B10%5D=&id%5B10%5D=&iy%5B11%5D=&im%5B11%5D=&id%5B11%5D=&iy%5B12%5D=&im%5B12%5D=&id%5B12%5D=&iy%5B13%5D=&im%5B13%5D=&id%5B13%5D=&iy%5B14%5D=&im%5B14%5D=&id%5B14%5D=&iy%5B15%5D=&im%5B15%5D=&id%5B15%5D=&iy%5B16%5D=&im%5B16%5D=&id%5B16%5D=&iy%5B17%5D=&im%5B17%5D=&id%5B17%5D=&iy%5B18%5D=&im%5B18%5D=&id%5B18%5D=&iy%5B19%5D=&im%5B19%5D=&id%5B19%5D=&iy%5B20%5D=&im%5B20%5D=&id%5B20%5D=&monr1=6&dayr1=16&monr2=6&dayr2=28&iyr%5B1%5D=2010&filenamein=&plotlabel=&lag=0&labelc=Color&labels=Shaded&type=2&scale=&label=0&cint=2&lowr=-8&highr=8&istate=0&proj=Custom&xlat1=-90&xlat2=-55&xlon1=0&xlon2=360&custproj=Southern+Hemisphere+Polar+Stereographic&level1=1000mb&level2=10mb&Submit=Create+Plot
David Gould says:
June 30, 2010 at 8:09 pm
“In three days, the slope of the Arctic extent graph will begin to drop off.
Mark it on your calendar.”
It looks as though you have been proven correct here, steven goddard. JAXA is reporting that the melt has stalled, with a provisional daily figure of loss of just 46,875 square kilometres, and this will likely be revised downwards (these provisional figures usually are). Well done. 🙂
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Now that the easiest to melt ice in Hudson Bay is all but gone and early at that, the high rate of melt is bound to slow temporarily. JAXA does not make the claim that the 2010 ice melt has stalled, that’s an impossibility. The ice volume continues to decline and that, by any definition, is melting. At some point large areas will reach the critical 15% criteria, resulting in large drops. It will do well to remember that ice does not only melt at the edges. An area of say 10×10 km (100 million M2 surface) exposes, on the sides, assuming a uniform thickness of 2 metres, an area of 80,000 M2 or 0.08%. ( air and water exposure combined) A melting of 50% volume will not reduce the extent by half. When thin ice sheets break up it will exaggerate the extent untill it reaches 15% and then, you guess, gone! Being triumphant about a smaller loss of extent without considering volume, is just plain dumb.
Lets have a simple pragmatic look at the situation;
For the period 2003 to 2009 the acerage daily melt from 1 July to the minimum of each year is 98,142 KM2 per day. The average end of melt date over the same period is 16 September (lowest 9 and highest 24) From 1 July to 16 September there are 47 melt days. If I use the average melt 2003-2009 of 98,142 times 47 days, then another 4.61 million KM2 will melt. Depending on the actual number for 30 June, I assume a starting point for 1 July 2010 to be near 8.80 million KM2. Deduct the average melt of 4.61 million KM2 and the result will be 4.19 million KM2, beating the 2007 record.
Hence, in order not to beat the 2007 record there would have to be unusual changes, such as; (1) an unusually early end to the melt period, (2) a daily melt well below average due to weather, or both. Keep in mind that only two melts were below average, 2006 at 75,000 KM2/day and 2003 at 80,400 KM2/day versus a 137,000 KM2/day melt in 2008 and another 3 years 2004/2005/2009 melted just over 100,000 KM2/day.
Melt halted? Impossible. Temporary slowing? Yes. Followed by a great accelleration,? In my opinion, yes. Beating the 2007 record? At least 50/50. Can I be wrong? Yes, the unpredictable weather may decide in unusual fashion, but remember that it can do so both ways.
David, We know that Henry Hudson was looking for the Northwest passage since about 1610. That’s roughly 400 years. It didn’t exist. To be conservative, lets say 350 years. It had not existed until recently, when we have found it two ouf the last three years and, at the end of June, it is starting to open up to the point where it is highly probable that it will be open by August.
No one argues that Arctic ice extent in any given year is the product of climate and weather. But, weather, pretty well by definition, is a year to year phenomenon…climate is long term. So, let’s see how likely it is that 3 of the last 4 years is due to weather alone.
With 3 of 350 years being open, the probability of any one year being open is 3/350 or 0.00857. The odds of 3 given years being open and one closed are 0.00857*0.00857*0.00857*.99143 (with .99143 being the odds that a given year is closed. These odds are 6.24e-7 (thats just under one in a million) that three given years will be open and the fourth closed.
Now, when we say three out of four, we have four chances to achieve that: first year closed, second year closed, third year closed, fourth year closed. So we multiply 6.24e-7*4, the number of combinations, and get 2.52e-6 or one chance in 400,000. That are the odds that the recent opening of the Northwest Passage is due to weather alone.
Curious Yellow says:
July 1, 2010 at 4:10 am
What’s your point, apart from avoiding the issue raised
I’m not sure what you’re trying to say in your comment.
Curious Yellow says:
July 1, 2010 at 4:10 am
“What do you think of the 7-day forecast for this town on the Russian arctic coast?”……..What’s your point, apart from avoiding the issue raised
I didn’t avoid it. I said “Yawn”.
I’m so going to hold you to that Curious Yellow. And what might your excuse be if it doesnt come to pass?
I have an alternate theory for you though. A certain amount of the ice pack each year is more vulnerable to early season melt. It should be remembered that each year pretty much all ice outside the Arctic Basin is going to melt by the September minimum regardless. If conditions are aligned that ice melts early. This doesn’t necessarily always govern how quickly the thicker ice in the Arctic Basin melts (particularly the multi-year ice). In some cases it might but it still very much depends on wind and ocean currents later in the season.
Take a very close look at the ice loss on a daily basis over the past 8 years (and I mean a close look on a daily basis). Ice will melt when the conditions allow and these conditions fluctuate greatly. There have been seasons such as 2006 where a lot of ice was lost early but then not as much late in the season. In 2009, the loss early in the season was light but from mid July onwards exceeded the 2007 loss for a few weeks.
Even this season, check the anomalies on either side of the Arctic Basin. On the pacific side the anomalies are close to the 30 year average whilst there are large anomalies on the Atlantic side. This shows the variability across regions.
Still too soon to call but I agree that the 45,000 result for the 30th doesnt necessarily mean anything, nor do the losses of May and June other than were unlikely to see the extent above 6,000,000 sq km this year.
I’m actually much more interested in the maximum extent to come. We will see if the coming la-nina and its cooler global temps sees a larger maimum extent like the previous la-nina did.
Seemingly out of no where the second and third derivative of Arctic ice extent suddenly went strongly positive in the last day or so. Is this the start of a something similar to what happened in 2006 (about a week later than now), or is it ‘just another wiggle’? This month should prove to be very interesting…
Aha, do I see a small hump there now?
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png
Dan M. says:
July 1, 2010 at 6:31
“We know that Henry Hudson was looking for the Northwest passage since about 1610. That’s roughly 400 years. It didn’t exist. To be conservative, lets say 350 years. It had not existed until recently, when we have found it two ouf the last three years and, at the end of June, it is starting to open up to the point where it is highly probable that it will be open by August……
Now, when we say three out of four, we have four chances to achieve that: first year closed, second year closed, third year closed, fourth year closed. So we multiply 6.24e-7*4, the number of combinations, and get 2.52e-6 or one chance in 400,000. That are the odds that the recent opening of the Northwest Passage is due to weather alone.”
If you bother to look I think you’ll find that the Northwest passage was transited on a number of occasions in the 20th century. Also over the 350 year period you are computing against there is undoubtedly a large number of years when the number of vessels attempting the transit was exactly none. If near realtime satellite mapping of Arctic sea ice and cadres of icebreakers to shepherd one’s passage had been available for the last 350 years your calculation might make a little more sense, but still not very much.
To my mind the best bit of evidence about what has been occurring in the Arctic over the last several decades is still this Rigor and Wallace 2004 study
http://iabp.apl.washington.edu/research_seaiceageextent.html
Rigor has recently updated the animation that accompanied the paper through 2009
Here is their commentary for the original animation
This animation of the age of sea ice shows:
1.) A large Beaufort Gyre which covers most of the Arctic Ocean during the 1980s, and a transpolar drift stream shifted towards the Eurasian Arctic. Older, thicker sea ice (white ice) covers about 80% of the Arctic Ocean up to 1988. The date is shown in the upper left corner.
2.) With the step to high-AO conditions in 1989, the Beaufort Gyre shrinks and is confined to the corner between Alaska and Canada. The Transpolar Drift Stream now sweeps across most of the Arctic Ocean, carrying most of the older, thicker sea ice out of the Arctic Ocean through Fram Strait (lower right). By 1990, only about 30% of the Arctic Ocean is covered by older thicker sea ice.
3.) During the high-AO years that follow (1991 and on), this younger thinner sea ice is shown to recirculated back to the Alaskan coast where extensive open water has been observed during summer.
The age of sea ice drifting towards the coast explains over 50% of the variance in summer sea ice extent (compared to less than 15% of the variance explained by the seasonal redistribution of sea ice, and advection of heat by summer winds).
If you watch the animation pay special attention to the difference in the drift patterns of the buoys in the SW corner before 1990 and after.
It shouldn’t be necessary, but I will point out that there are more than “Six Degrees of Kevin Bacon” between the state of the BG and the TPD and anything anthropogenic.
Dave Wendt says:
July 1, 2010 at 1:44 pm
“If you bother to look I think you’ll find that the Northwest passage was transited on a number of occasions in the 20th century. Also over the 350 year period you are computing against there is undoubtedly a large number of years when the number of vessels attempting the transit was exactly none. If near realtime satellite mapping of Arctic sea ice and cadres of icebreakers to shepherd one’s passage had been available for the last 350 years your calculation might make a little more sense, but still not very much.”
Nice to see some common sense. I would imagine a Northwest Passage much more difficult to identify without the use of radar, satellite images and as Dave said a “cadre of icebreakers”.
I note that I have not yet seen anyone try to analyse the impact of the presence of increasing numbers of icebreakers in the Arctic circle on the structural strength of the icepack and its vulnerability to early seasonal breakup.
I wonder what would happen if we banned all icebreakers for a couple of seasons.
David says:
July 1, 2010 at 6:43 am
Yes you can hold me to that. As for the sea ice maximum, it will still trend down. Arctic sea ice cannot be compared to or related with the Antarctic. Arctic sea ice growing in winter soon reaches land masses east, west and north (except for the relatively narrow opening of the Berents Strait). Any further extension must mostly occur south. Antarctic sea ice has no physical obstructions, can extend in all directions. The sea ice freezing in winter, melts again in summer. I still expect the maximum to decline according to trend. Could it be more next March, yes it could. Could it be less, yes it could. It trend is but a straight line representing average.
The sea ice extent as of now shows 2010 to be 950,000 KM2 less than 2009. That’s a lot to make up, about 21,000 KM2 per day over the remaining melt season. Up until today, 2010 has had eleven 100,000 KM2+ days, versus three in 2009. Between 2 and 25 July, 2009 had eleven 100,000KM2+ melt days. The next 4 weeks will reveal all.
Ok I’ve seen enough to make a prediction for this year.
Looking at daily rates of ice loss over the past 8 years and then cross checking this agains the ice losses for specific areas this year, my conclusion is that we’ve most likely already seen the heaviest daily ice losses for this season.
On a 15 day moving average I would consider the average daily loss has probably maxed out at about 86,000 sq km per day and this will now start to decrease. Most of the areas that tend to lose ice the quickest have already done so this season and the rate of loss in the Arctic Basin and other inner regions is has in past years been somewhat slower than the outlying regions.
I would imagine we will now follow a rate of loss similar to what we saw in the 2006 melt season from July to September and the final minimum extent will probably be a little under the 2009 minimum. Somewhere in the vicinity of 5,100,000 sq km.
Hey, but I’m not a scientist so if I’m right you can chalk it up to a lucky guess
Hey, that’s my guess! 🙂
David W says:
July 1, 2010 at 8:41 pm
David,
We now enter the vagaries of sea ice extent versus volume. If the extent comes out roughly equal to 2009 simply because the remaining melt reduces volume, but not so much the sea ice extent, then what are the implications for 2011 and after? My guess is that in successive years we will get a year after year a larger loss of “quick to lose ice”, leading to a year by year reduction of the September sea ice minimum. Inevitably, thin ice in the arctic basin will fragment much easier, spreading over a larger area, thereby creating a higher extent measurement based on the 15% rule, yet still less ice.
I notice that that the DMI Centre for Ocean and Ice
http://ocean.dmi.dk/arctic/icecover.uk.php
has the sea ice extent at about 6.5 million KM2 based 30% of sea ice or more.
What is your reasoning for anticipation a copy of the 2006 scenario? Is it anticipating unfavourable weather or currents or cloud or a combination thereof? I tend to take into account that 2008 and 2009 were partial recovery years from the unusual large melt of 2007. Perhaps 2009 is now the new ‘normal’ minimum extent.
Because looking at the past 8 years, 2006 was the only other season that had the level of early season melt like we’ve seen this year. At the start of July 2006, I’m sure people would have been saying they were headed for a record melt. It never eventuated.
I think a similar thing has happened this year we had strong el-nino conditions and very warm temps through spring and this has cause the early melt.
Were now seeing temps cooling as we head into what looks to be a fairly strong la-nina event. I know the SST anomaly charts are still showing some fairly warm SST’s around the Artic circle but I just dont see it as a repeat of 2007.
If this years minimum is in the 5.1-5.2 sq km range I think we might see the winter maximum get well into positive territory should the La-nina turn out to be a strong one and the following years minimum will then be over 6 million sq km.
I might add, if you think the SST anomalies on the Atlantic side will guarantee a fast melt for the remainder of the season check out the anomalies in July and August 2006. As warm or even warmer than were seeing this year!!
David says:
July 2, 2010 at 5:37 am
I can see your reasoning, which may well be right, but the one difference I see between 2006 and 2010 is that a lot of multi-year ice has been lost. How would 2006 have responded with far less multi-year ice? I guess we’ll never know. As for La NIna this year, I feel that the jury is still out. The SOI briefly rose to +10 beginning of May but has slowly, but steadily fallen back to +1.8. My feeling is that, yes there will be a LaNina but not a strong one. For the moment the SOI is in neutral territory hovering close to zero. However, I have no rational reason other than looking back over previous El Nino events and La Nina’s following. The only pattern I can detect is that since 1977 El Nino’s were followed by LaNina’s in 1988/89, a weal La Nina in 1995/96, a prolonged La Nina in 4 waves 1998/2001 and a La Nina in 2007. All year gaps inbetween were neutral. About 35-40% of El Nino’s are followed by a La Nina in the same year. If the 2010 La Nina does not evolve or is weak, then the 2011 melt season may be critical for the arctic.
Correction; typo “1988/89, a weak La Nina in 1995/96”