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Post by thermostat on Jun 25, 2012 4:58:14 GMT
Surprised to see that 66% of pollsters think the minimum this year will be greater than 2011 of 4.33 We can only wait and see neilhamp, What is more interesting to me than 66% of respondents on this forum being above 4.33 is that this number, and the guesses of forum members now accept the present reality. (Numbers below 5.0 were previously relatively rare on this forum). The weather will tell, as always, but we go into this year's melt with an arctic sea ice pack that has taken a beating over multiple years. Thus, while I agree that we can only wait and see, I suspect that the behavior of the 2012 ice pack cannot be predicted based on historical factors.
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Post by thermostat on Jun 30, 2012 1:42:08 GMT
Considering the new normal, there was an article in Science Daily about the Barents Sea; "Atlantic Heat Constrains Arctic Sea Ice Extent" www.sciencedaily.com/releases/2012/06/120626065007.htmWhile it is basic physics to note that it takes heat to melt ice, this article introduces the wrinkle that heat can prevent ice formation as well melting existing ice. One implication of this observation, not stated explicitely here, is that additional new heat in the Arctic System is not just preventing ice formation but rather reducing ice thickness on a broader scale.
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Post by thermostat on Jul 2, 2012 4:19:03 GMT
The influx of heat into the Arctic Sea is an interesting element in understanding the present ongoing reduction of ice in the Arctic. The observation that the flow of heat from the Atlantic into the Barents Sea is now reducing ice formation in this region as observed, is only part of the process. Additional heat is also entering directly into the Central Arctic Basin, for example, via the Fram Strait where it has the capability to melt ice from below. Given the relatively large heat capacity of water in comparison to the heat capacity of air, the influx of this heat has important consequences.
For example, back in 2007, when the Arctic Sea Ice experienced a substantial reduction, the influx of ocean heat from the Bering Sea is now recognized as an important contributing factor.
Since most of the heat that has been added to the climate system during the present warming has been accumulated in the oceans, the movement of this heat into the Arctic, and consequences of this movement, are important.
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Post by thermostat on Jul 4, 2012 5:26:24 GMT
Another factor that is adding additional heat to the Arctic this year is the absorption of solar radiation directly into the Arctic Sea as a result of the early fragmentation if the Sea Ice as a consequence of reduced ice thickness. Arctic Sea Ice junkies have been commenting about the early fracturing of the ice in the central arctic basin. Overall albedo also appears to be reduced, providing for additional energy input during this period of maximal solar energy input. These events are consistent with expected 'arctic amplification' responses. Regarding the sea ice minimum, it will take less in the way of weather to get more in the way of melt this year because of the reduced sea ice volume.
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Post by icefisher on Jul 5, 2012 23:05:33 GMT
Another factor that is adding additional heat to the Arctic this year is the absorption of solar radiation directly into the Arctic Sea as a result of the early fragmentation if the Sea Ice as a consequence of reduced ice thickness. Arctic Sea Ice junkies have been commenting about the early fracturing of the ice in the central arctic basin. Overall albedo also appears to be reduced, providing for additional energy input during this period of maximal solar energy input. These events are consistent with expected 'arctic amplification' responses. Regarding the sea ice minimum, it will take less in the way of weather to get more in the way of melt this year because of the reduced sea ice volume. For it to reach the conclusions you have reached you need to quantifiy not just that but the entire process. First one must factor in the fact that melting ice has very little albedo absorbing almost all of sunlight. It is fresh snow that has high albedo. Thus precipitation is the best indicator for changing albedo, not melting of ice. And of course offsetting the slightly higher albedo of ice over water is the fact that ice is an excellent insulator compared to convecting liquids. Warm ocean currents moving from the equator poleward is trapped under ice expending its energy in melting ice instead of radiating heat to space as it would do in the absence of ice. You posted about that process claiming it was a major factor in this years ice melt but you didn't give us a value for it. Nor did you give us a value for additional heat from the sun absorbed after the ice is melted. Which is larger? Since they offset each other its the net figure that counts.
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Post by thermostat on Jul 6, 2012 2:33:25 GMT
Another factor that is adding additional heat to the Arctic this year is the absorption of solar radiation directly into the Arctic Sea as a result of the early fragmentation if the Sea Ice as a consequence of reduced ice thickness. Arctic Sea Ice junkies have been commenting about the early fracturing of the ice in the central arctic basin. Overall albedo also appears to be reduced, providing for additional energy input during this period of maximal solar energy input. These events are consistent with expected 'arctic amplification' responses. Regarding the sea ice minimum, it will take less in the way of weather to get more in the way of melt this year because of the reduced sea ice volume. For it to reach the conclusions you have reached you need to quantifiy not just that but the entire process. First one must factor in the fact that melting ice has very little albedo absorbing almost all of sunlight. It is fresh snow that has high albedo. Thus precipitation is the best indicator for changing albedo, not melting of ice. And of course offsetting the slightly higher albedo of ice over water is the fact that ice is an excellent insulator compared to convecting liquids. Warm ocean currents moving from the equator poleward is trapped under ice expending its energy in melting ice instead of radiating heat to space as it would do in the absence of ice. You posted about that process claiming it was a major factor in this years ice melt but you didn't give us a value for it. Nor did you give us a value for additional heat from the sun absorbed after the ice is melted. Which is larger? Since they offset each other its the net figure that counts. icefisher, Great points. We now have many years of observations to look at and are searching for explanations. This is what the ongoing discussion among the Arctic Sea Ice junkies is about. ie, we are observing this ongoing melting and asking 'how does it work'? That is, people are making observations and formulating hypotheses, not drawing conclusions. The ongoing melting of the Arctic Sea Ice is clear from the data, but the physical mechanisms that are producing this result are not well defined. Albedo, for example appears to be a central factor. (the significance of the reduction in snow cover over land is obvious). The current discussion includes the affect of 'blue ice' (ie. ice so thin that the ocean below shows through.) Also, the change in albedo that results from the formation of melt ponds on the surface of the sea ice is also an issue. Cracks in the ice that expose open water are also a factor. Black carbon coming from China has been mentioned on this forum before and is a factor. Overall, albedo in the arctic may be reduced by a variety of mechanisms. But, as you say, what is the relative contribution of melt from above vs melt from below? The thermohaline gradient would appear to preclude significant melt from below. Thus, regarding melt from below due to transport of heat from the south, you are quite correct, this is a novel alternative hypothesis (but one that I personally favor right now). Nevertheless, the melt keeps increasing. Why? How?
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Post by thermostat on Jul 6, 2012 3:10:08 GMT
The NSIDC report for June 2012 has now been released, "Rapid sea ice retreat in June" nsidc.org/arcticseaicenews/"The ice extent recorded for 30 June 2012 of 9.59 million square kilometers (3.70 million square miles) would not normally be expected until July 21, based on 1979-2000 averages. This puts extent decline three weeks ahead of schedule." Regarding albedo, "Snow cover over Northern Hemisphere lands retreated rapidly in May and June, leaving the Arctic Ocean coastline nearly snow free. June 2012 set a record low for snow extent (for a 45-year period of record spanning 1967-2012) by a significant margin. Snow extent for June 2012 was more than 1 million square kilometers (386,000 square miles) below the previous record set in 2010. Snow extent for 2011 was a close third lowest. May 2012 had third lowest snow extent for the period of record. This rapid and early retreat of snow cover exposes large, darker underlying surfaces to the sun early in the season, fostering higher air temperatures and warmer soils.
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Post by thermostat on Jul 8, 2012 2:59:02 GMT
On a related note, the University of Washington PIOMAS projection of Arctic Sea Ice volume just came out; psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png?%3C?php%20echo%20time%28%29%20?To clarify, various sites measure Sea Ice extent which is the area with at least some (defined) sea ice concentration such as 15% or 30%. In contrast, sea ice area calculates the actual surface area covered by ice. Sea ice volume is a measure of the total amount of ice altogether, given that some areas have thin ice, some have medium ice, and some have thick ice. While sea ice extent and area give some information about the surface of the Arctic currently covered by ice, the volume number provides information about just how much ice we are talking about.
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Post by thermostat on Jul 13, 2012 20:07:37 GMT
The updated 2012 Arctic Sea Ice minimum projections at ARCUS came out this week. Remember, these numbers are based on NSIDC September average extent rather than the lowest single daily value which is what we are using in this particular poll. www.arcus.org/search/seaiceoutlook/2012/julyThere is some interesting information under tha pan arctic tab as well as under the regional tab.
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Post by thermostat on Jul 13, 2012 21:22:01 GMT
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Post by thermostat on Jul 16, 2012 5:12:46 GMT
The possible opening of the Northwest Passage as well as the opening of the Northern Sea Route (around the Russian side) are currently interesting topics regarding this year's Arctic Sea Ice melt. Speculation is that both routes will again open this year with the Asian Northern Sea Route becoming passable by the end of July (we'll see), and the NWP opening in the latter part of August. Related to the previous post on the current weather pattern, some are predicting that the forecast low pressure system will actually promote clearing of sea ice from the East Siberian Sea over the next 10 days. It will be interesting to see if this occurs. The Northwest Passage is presently full of ice. Still, the weather has provided for abundant solar irradiation this year which has been further observed by warm temperatures at various land stations within the passage (this site is a good link to get current temperature information around the Arctic, weatherspark.com/#!dashboard;ws=28170 (navigate the map and click on points of interest) The progression of events on both the Asian and Canadian side will be interesting to follow as this year's melt progresses.
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Post by neilhamp on Jul 16, 2012 7:30:19 GMT
Just returned from 2 weeks holiday Sea ice extent not looking good following very close to 2007 levels
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Post by Ratty on Jul 17, 2012 5:11:00 GMT
Questions from an amateur: . Does it matter if all the Arctic sea ice melts? . If it does, what would it indicate? . What would be the global flow-on effect?
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Post by thermostat on Jul 18, 2012 4:02:05 GMT
Questions from an amateur: . Does it matter if all the Arctic sea ice melts? . If it does, what would it indicate? . What would be the global flow-on effect? ratty, Take a look at the DMI site on Arctic temperatures ocean.dmi.dk/arctic/meant80n.uk.phpNote how, clicking on various years, the summer temperatures always stay close to zero degrees C (the freezing point of water; 273 deg Kelvin.) This is because it takes heat to melt ice and as long as there is ice in the Arctic Sea the surface temperature will stay close to zero degrees C through the summer as the sea ice absorbs heat from the air. If the Arctic Sea becomes seasonally ice free the surface atmospheric temperatures in this region will increase significantly. The broader affects of such a change are a matter of speculation, but one concern is that such a change in surface temperatures could be to accelerate melting of the ice sheets in Greenland and the Canadian Archipelago, which are currently constrained by atmospheric temperatures.
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Post by neilhamp on Jul 19, 2012 6:59:28 GMT
Thanks for all your help on smaller image sizes I have successfully followed your instructions to reduce the size of this image The comparison with 2007 looks omminous for the 2012 minimum Look at all that thin ice! Unless there is a dramatic change we can expect record lows this year!
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