This is John Christensen's Typepad Profile.
Join Typepad and start following John Christensen's activity
Join Now!
Already a member? Sign In
John Christensen
Recent Activity
Hi George, Yes, the bridge is still in place. You can check this on the DMI ice temp chart: Or one a DMI satellite image (ASAR has a nice view):
Toggle Commented yesterday on PIOMAS April 2014 at Arctic Sea Ice
Great to see that the writer is looking for advice from an 'expert community' for the upcoming fiction piece. One time this clearly did not happen, was when the significant Hollywood production G.I. Joe - Rice of the Cobra missed the point that ice floats.. What makes this scary, is that someone asked if it could be true that ice would sink when the pack is blown to pieces, and the highest rated answer is that ice floats on salt water, but sinks in fresh water.. ;-) You cannot make this up..
Toggle Commented 2 days ago on Research for a novel at Arctic Sea Ice
Link to the DMI ice drift map, which clearly shows the continued northernly flow in Laptev: This would be a significant difference from the setup a year ago, where the ice was stable here, while quite similar to the situation two years ago leading to unprecedented ice melt during summer months. The early opening of the waters in Laptev should have a negative impact on the ice both due to early access of sun radiation to the water surface as well as reducing chances of creating the cyclonic environment we witnessed last year.
Toggle Commented 6 days ago on PIOMAS April 2014 at Arctic Sea Ice
Sorry Neven, for deviating from the topic here - I will make this just one comment. Hi Chris, You stated " I've said before I don't get why some follow a system in a death spiral and keep rooting for ice survival." My counter-argument is that it's not about the Arctic Sea Ice, but about the global eco-system that we have adapted to. Consciousness about global warming and sea ice is not global; people in Syria, Haiti, Central Africa, Africa's Horn, and many other places have accute challenges of poverty, disease, and threats to their lives, which makes global warming a remote intangible concept of low priority. I don't believe any population will remain in their huts, houses or caves made of dirt or straw at the risk of malnutrition, disease and exploitation from stronger powers in their area. They will eventually be educated and will want basic levels of social and economic freedom and stability. It took the Western world about 200 years to reach a point where we start seeing energy consumption levels go down in some countries, as well as increase in transition to renewable energy sources. See example of Denmark: It will take another 100-150 years to get the rest of the world to this point (probably quite optimistic), and this would even require many of the remaining countries to leap frog from subsistence farming to a modern society based on economic exchanges. So yes, I am rooting for the ice, not to be naive about what is happening in front of us, but because I do not see how the entire world can transition to a different mode of energy consumption within years or a few decades given the social and economic situation of nearly a billion people: From Worldhunger: The United Nations Food and Agriculture Organization estimates that nearly 870 million people of the 7.1 billion people in the world, or one in eight, were suffering from chronic undernourishment in 2010-2012. Almost all the hungry people, 852 million, live in developing countries, representing 15 percent of the population of developing counties. There are 16 million people undernourished in developed countries (FAO 2012). The number of undernourished people decreased nearly 30 percent in Asia and the Pacific, from 739 million to 563 million, largely due to socio-economic progress in many countries in the region. The prevalence of undernourishment in the region decreased from 23.7 percent to 13.9 percent. Latin America and the Caribbean also made progress, falling from 65 million hungry in 1990-1992 to 49 million in 2010-2012, while the prevalence of undernourishment dipped from 14.6 percent to 8.3 percent. But the rate of progress has slowed recently. The number of hungry grew in Africa over the period, from 175 million to 239 million, with nearly 20 million added in the last few years. Nearly one in four are hungry. And in sub-Saharan Africa, the modest progress achieved in recent years up to 2007 was reversed, with hunger rising 2 percent per year since then.
Toggle Commented 6 days ago on PIOMAS April 2014 at Arctic Sea Ice
Thank you for sharing Jim, and I agree that this view does seem to be overstating the MYI, while being in better agreement with HYCOM on structure.
Toggle Commented 7 days ago on PIOMAS April 2014 at Arctic Sea Ice
Thanks to Chris for a great regional PIOMAS update! One item I noticed in particular is the considerable difference between your gridded view of ice thickness compared to HYCOM: 'Your' view has a lot more ice in the Central AO, while HYCOM is showing a significant branch of thicker ice in the Beaufort and Chuckchi Seas. I hope you have it more accurately placed than HYCOM, as the lower latitudes showing on HYCOM does not bode well for summer melting rates (depending on your view point). And your statement: "I don't expect 2014 to beat 2012, but I do expect a more exciting year than 2013". What is this? ;-) I found 2013 extremely exciting like the thriller where the hero is up against impossible odds, but starts out amazingly well, then almost succombs, and finally makes it through with few casualties. I always favored the underdog..
Toggle Commented 7 days ago on PIOMAS April 2014 at Arctic Sea Ice
I am refering to this excellent blog entry by Neven last year: And a key abstract from that entry: The Summer Cyclone Maximum over the Central Arctic Ocean Mark C. Serreze and Andrew P. Barrett, 2008, Journal of Climate From the abstract: A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean. This pattern is associated with the influx of lows generated over the Eurasian continent and cyclogenesis over the Arctic Ocean itself. Its seasonal onset is linked to the following: an eastward shift in the Urals trough, migration of the 500-hPa vortex core to near the pole, and development of a separate region of high-latitude baroclinicity. The latter two features are consistent with differential atmospheric heating between the Arctic Ocean and snow-free land.
Toggle Commented Apr 8, 2014 on PIOMAS April 2014 at Arctic Sea Ice
Thanks for your comments George and agreed on the ice notions. Regarding the impact of early snow melt in Siberia, it will be very interesting to see if this will lead to early melting of ice on the Siberian side of the Arctic, or if the opposite will happen, namely that the temperature difference between ice-covered AO and heated surrounding continents will create a repeat of last year..
Toggle Commented Apr 8, 2014 on PIOMAS April 2014 at Arctic Sea Ice
Hi Jim, I see from the Forum that you are suggesting this ice is "falling apart" and not refreezing, is that correct? Since it is -15 - -20C in this corner of the Laptev Sea (from the DMI 60N weather chart) would you agree that the open water is caused by the pack compacting towards the North, or are you suggesting this temperature is too high for refreeze, or the data is incorrect on DMI?
Toggle Commented Apr 8, 2014 on PIOMAS April 2014 at Arctic Sea Ice
D said: "Early snowmelt in Siberia and much warmer temperatures on the Siberian side of the Arctic combined with southerly winds have thinned the Siberian Arctic ice." The ice has not thinned due to warmer temperatures or melting, as it seems you are suggesting. The ice has been moved north due to prevailing offshore winds in Laptev over the past weeks, as you see here: If that pattern had persisted I would agree that more ice would go out via Fram, but luckily (if it holds) it seems the weather has now changed to a weak central Arctic high, which causes westerly winds in the Fram Strait, hopefully slowing down ice export: Both HYCOM and the DMI weather chart seem to support some strengthening of the ice west of Severnaya Zemlya in the coming week, but it is very late in the season for ice build-up..
Toggle Commented Apr 8, 2014 on PIOMAS April 2014 at Arctic Sea Ice
Need to agree with philiponfire - and my vote goes for P-makers excellent account of somewhat possible events..
Toggle Commented Apr 8, 2014 on Research for a novel at Arctic Sea Ice
Thank you for another great, and anticipated, update Neven! While I would not agree that "last year's rebound has been fully negated after a couple of relatively warm months", there is certainly not much left, and we are basically back to relying on weather - which in any case is still the most prominent factor in determining summer minimum ice area and volume. The two positive points: - We have significantly more second year and MYI than a year ago - For main melting areas in April and May (Barents, St. Lawrence, Bering, and Okhotsk), we had last year about 300km3 more ice than this year (assuming average thickness of .75M and using CT area numbers) The negative points: - Baffin has about 300km3 more ice this year compared to last year, which will melt out nearly completely in June/July, but will the increased ice cause any protection from ice discarting from the Hudson Bay and nearby strait? - I don't like the compaction of ice east of Severnaya Zemlya, as this opens up the possibility of open water earlier in the summer than last year - prefer any ice cover compared to open water in main summer months. To speak of the weather, it does seem the Arctic pressure area is disconnecting itself from the Siberian weather (as the snow is melting fast over there), which I think is a good thing, exactly as we saw last year, and it may - if all goes well - help to insulate high and low areas over the Arctic from adjacent continental pressure areas. Amazing spectacle!
Toggle Commented Apr 8, 2014 on PIOMAS April 2014 at Arctic Sea Ice
The ice has been compacting on the side of Barents/Kara and even into the AO the past few days with possibly some melting even in Okhotsk, but with reduced winds and change of direction to have southern flow in Bering, I would anticipate max in area and extent to come in the next 7 days (at least on Arctic ROOS), but would also think it would be possible still to top the recent max on CT with the right conditions in place..
Toggle Commented Mar 12, 2014 on PIOMAS March 2014 at Arctic Sea Ice
Hi Chris, Thank you very much for the extensive feedback - will need to review more closely in the morning. Regarding the continental warming and Arctic highs or lows; how does your Siberian high ridge and Greenland ridge correspond with the repeated Arctic lows/cyclones we experienced throughout most of last summer? Others had argued then that these Arctic cyclones (See Neven's entry on that) were caused by temperature difference between Arctic ice-cover and surrounding warm continents..
Toggle Commented Mar 10, 2014 on PIOMAS March 2014 at Arctic Sea Ice
Wanted to share also this interesting article from Sept. 2013 on relationship between NAO index and Northern Hemisphere mean temperature: The article concludes that the NAO influences NH mean temps (not discussing in detail hos this is possible) with a 16 year lag between change in NAO and impact on NH temps. Given NAO negative trend since the late 90's it is argued that we can expect NH temp increase to pause or even see NH temp decreases in the next couple of decades. If this holds, it could both be argued that part of recent NH warming was caused by positive NAO back in the early 80's to mid-90's, and we will see 'masking' of global warming in the next couple of decades for the NH due to NAO going counter to CO2 and rising temps. It will be interesting if any of this will reflect in Arctic sea ice volume development, or if we have reached a point where extraordinary protective weather events are required, as we saw last year, to preserve the ice.
Toggle Commented Mar 10, 2014 on PIOMAS March 2014 at Arctic Sea Ice
Thank you Neven for another great PIOMAS update! Allthough we still have approx. a month and a half before reaching max. volume, we are already seeing the outline of how 2014 is considerably different from 2013, even with near identical volume by end of February. Still: - By end of Feb. 2013 82.4% of ice volume was gained since minimum, while by end of Feb. 2014, only 74.2% was new ice (both numbers disregarding MYI loss through Fram and other straits since minimum, so actual percentage are higher for both years). - Feb. 2013 saw volume increase of 3055 km3 compard to just 1847 km3 in Feb. 2014, so lots of young ice late in the freezing season last year, and we saw last year in April that max. volume was reached sligthly earlier than in 2012 and that initial volume decline was stronger in 2013 than in 2012, probably due to lots of young ice at lower latitude melting out quickly. - It would be great to see regional breakdown of recent volume development, so I will look out for updates from Chris on this. HYCOM model views seem to indicate a varied distribution by this time compared to last year: - Barents, Okhotsk, Bering: Less volume than last year - Arctic Ocean: Similar or less volume than last year?? - Greenland, Baffin: Similar volume - Beaufort, Chuckchi, ESS, Laptev, Kara, Hudson, St. Lawrence: More volume than last year If HYCOM is reasonably reliable on thickness, I am quite concerned, since it would seem necessary for the Arctic Ocean to have less volume than last year - which was created in the SSW/cracking event - in order for the total volume to match the volume of last year.. However, this begs a question to Chris: Is the total area for PIOMAS exactly the same as for CT, or could there be deviations in marginal regions, such as e.g. St. Lawrence or the limit of Okhotsk? Secondly, it also highligths the importance of having the right conditions for ice volume growth in place (cracking and compaction, combined with considerable cold), since it seems the -20 - -25C and calm weather in many areas this winter simply did not provide for significant ice growth. To other comments regarding early snow melt on surrounding continents, I will repeat what I mentioned last spring that I see this as beneficial to the ice cover, since this will move the high pressure areas away from the Arctic seas towards the main continental areas of North America and Russia/Siberia, and possibly create similar type low pressure/cyclone formation over Arctic seas, which clearly preserve the ice well, at least from late spring to some time early August.
Toggle Commented Mar 10, 2014 on PIOMAS March 2014 at Arctic Sea Ice
In anticipation of the next PIOMAS update I wanted to share a brief comparison of volume (km3) by the beginning of each month compared to the same date a year before: Month Year Volume Difference Nov. 1 12 -696 Dec. 1 12 -974 Jan. 1 13 -1152 Feb. 1 13 -746 Mar. 1 13 201 Apr. 1 13 -39 May 1 13 -271 Jun. 1 13 825 Jul. 1 13 1.769 Aug. 1 13 991 Sep. 1 13 1.596 Oct. 1 13 1.793 Nov. 1 13 2.086 Dec. 1 13 1.548 Jan. 1 14 1.889 Feb. 1 14 1.252 Mar. 1 14 ? As you see, Nov. and Dec. '12 did not provide strong ice volume gain, but it turned in January and then more significantly in February with the SSW/cracking event and strong freeze. After that, March and April '13 did not fare well compared to the year before, but May and June changed the picture dramatically. Finally, last fall/early winter months were great for Arctic ice build-up, until January, where we dropped about 600 km3 compared to the year before. We are likely to have gotten even closer in February, since we did not have strong cold, so would probably leave us with 100-400 km3 more ice than last year by end of Feb.? However, we should have the slight upside that last year we had considerably more ice in Okhotsk, Bering, and Barents, which is due for March-early May melting, so might leave us slightly better off than last year by May 1 - ceteris paribus..
Hmmm, HYCOM indicates we should have just above 2 meters of ice in that area.. Makes you wonder if the difference is between model and measurement, or if the HYCOM tends to include snow cover also?
Thanks Jim, yes the , got in the way.. The position of the high pressure seems condusive for getting the Beaufort gyre in gear, which will push/pull the ice towards the ESS side of the Arctic. However, with -15 to -25C in the area, cracks should fill up quickly in the ice that is 1.7-3 meters thick. With later changes in wind or current, new ice will easily get compacted against the thicker surrounding pack, so uncertain whether the cracking would be overall negative (higher mobility) or positive (net volume gain)..
Thanks Jim Hunt for the link to the DMI sea surface temp, which is a great addition to other maps available. As can be seen from todays image (, a number of interesting features are visible: - Cracks in the Beafort ice, probably due to the clockwise winds of the central Arctic high currently in place - Apparently landlocked ice in Laptev towards Kara, where offshore winds are nearly creating a gap between landlocked and floating ice. This should be a primary spot of ice formation right now. - Nice views of the Nares Strait ice arches to the North splitting cold from very cold ice, and to the South splitting cold from significantly less cold ice. The ice temperatures would seem to indicate the arches are very solid at this point, but let's see when spring arrives.
All, It has been a pleasure following all of the blog entries in the last few days, encouraging me to add a few comments: @Chris/P-maker: Great discussion, very helpful to those of us with less formal studies in this field. I intuitively understand Jennifer Francis' argument that a strong jet stream will plough through a local low or high, but since most of our winter time highs and lows of significance are supported by considerable topographical features (Greenland, the Rockies, Norwegian west coast and the Central Siberian Plateau), I could also see the jet stream working like a water hose being sprayed against a rock in its path: If you increase the water speed of the hose, the water will deviate more from its original path, once it hits the rock, not less. @Neven/idunno on Continents: I would tend to agree with idunno that we need to observe the continents more closely, as the Arctic is warming. It has received very little publicity, but as I have referenced a couple of times the unusual Central Siberian Plateau high of this winter has been impressive, causing significant negative deviation from average temps. ( So did the lack of Arctic ice influence/enforce the Siberian high, or was the Siberian high so forceful that it impacted weather around the NH? Or both ways to some degree? David wrote on temps: JC, I'd like to point out that taking the average continental US temperature anomaly isn't going to tell us much about a wandering jet stream. Think like the statistician with a foot in boiling water and the other in ice water saying 'on average I feel fine'. To do an analysis like that you'll have to at least break the temperature down into regions and look for both high and low anomalies by region. I think the real mark of a meandering jet stream is simultaneous high low anomalies in different regions. You are right in principle, and I did point out that I had not performed any detailed analysis. However, I would argue that if CONUS temps are 3-4C below average, you will always find even higher regional deviations, as the US rarely would observe similar weather pattern coast-to-coast. I did check the regional temperatures for California, and West Virginia (WV was near the center of the January cold spell this year) for the coldest Januaries across CONUS( 1901-2000 average = -0.9C): 1912 (-4.0C): Cali: Warm, WV: Cold, supporting standard jet stream 'dip' across mid/eastern US, while west coast stays warm. 1918 (-4.3C): Cali: Cold, WV: Cold, supporting very wide/strong jet stream dip, impacting across the US. 1930 (-4.4C): Cali: Sligthly cold, WV: Average. Major cold outbreaks this year across Colorado, Texas deep into the middle of the continent. Narrow and very strong jet stream dip. 1937 (-3.7C): Cali: Coldest on record, WV: Warm. This was an usual month with the weast coast being very cold, but near average to the east. 1940 (-4.4C): Cali: Warm, WV: Cold. Standard jet stream dip across central/eastern regions, leaving west warm. 1963 (-4.1C): Cali: Sligthly cold, Wv: Sligthly cold. Very wide jet stream dip, slightly less intense cold. 1977 (-4.8C): Cali: Sligthly cold, WV: Coldest January on record. Very wide jet stream dip, very intense in eastern regions. 1979 (-5.5C): Cali: Slightly cold, WW: Cold. Coldest CONUS January on record. Very wide jet stream dip, with intense cold in central regions. 2014 (-0.95C): Cali: Very warm, WV: Cold. Standard jet stream dip across central/eastern regions, leaving west warm, but not near record level cold and reduced geographical reach of jet stream dip. And finally, top ten cold januaries for West Virginia: 1977: -8.2C 1940: -6.6C 1918: -6.6C 1978: -5.2C 1912: -5.1C 1948: -4.5C 2014: -4.3C 1994: -4.3C 1970: -4.3C 1981: -4.2C So this is my point: Yes, we saw a US cold outbreak due to a dip in the jet stream, but the dip was both less intense in temperature deviation as well as in geographical reach, indicating that prior major jet stream dips have been either larger, colder, or of longer duration. The jet stream of this year has been either smaller, less cold, or of shorter duration, and therefore does not merit the branding of 'extreme weather' IMHO. Again, if there is any data available pointing in a different direction, please share that. On the Euro/Asian side of things this winter, the NAO played an insignificant role, as Greenland and the Central Siberian Plateau seemed to have had the main interaction with the jet stream, splitting it in a northernly branch pushing lots of moisture north into the Barentz region, as well as allowing a strong jet stream going across mid-Asia regions south of Siberia across China into the Pacific and then moving towards the North causing the high anomalies in Alaska and north-east Pacific. Did lack of Sea Ice cause the Siberian high to get stronger than usual this year, or did the indecisive NAO allow the Siberian high to get well-established, most likely leaving it in place, until spring-time heat enters the area? If there is no new data available yet to support the theory of extreme weather becoming more likely with a weakened jet stream, it should then be verified that a strong jet stream to some degree prohibits or limits the occurence or extend of these same extreme weather events. This is what the data does not seem to support and why I find that without support in data analysis, the theory does become speculative.
Werther, I follow this blog due to the focus on Arctic Sea Ice, and how this is being impacted by our warming climate, caused by increase in atmospheric CO2. I have been trying to make sense of the arguments around the 'weather weirdness' and 'extremes', but cannot find scienfic reason or data supporting this, and will refrain from any further comment on that topic.
Good morning Werther, I have not compiled a list of data to provide the counter-argument to Dr. Francis work, but I have not been able to find a data confirming that we experience an increase in weather extremes at our latitudes that should be caused by persistent changes in the jet stream. Yes, my link was for NOAA data for CONUS, but UK Met also shows that the wettest January was in 1928, second wettest was in 2008, while this year was a close tie in third place with 1948: Driest UK Januaries according to Met were in: 1997, 1963, 1964, 1987 and 1929 in that order, which must have been caused by blocking patterns as well. January '14 average temperature for the UK came in on a 15th place since 1910 (same Met data), tied with 1938 and 1993, so the temperature did not deviate to any extreme extend. Is there data available to support Dr. Francis' argument?
So does the warming climate (or changes in the jet stream) cause more or stronger extreme weather events like tropical cyclones globally? No, it does not seem so: The ACE (accumulated cyclone energy) from all tropical cyclone activity globally is on a downward trend, and while the long-term trend for major hurricanes is going up sligthly, you see that we have seen steadily less major tropical hurricanes since 2005. So while a warmer, more humid climate will increase precipitation and cause a number of changes compared to prior decades, it seems the decline in temperature gradient between the arctic and tropic regions may have the effect to reduce tropical hurricane activity - or some other factor plays in here.
From the same NOAA data you will notice that since 1990, there has not been a single year, where the US January negative temp anomaly (48 states) has exceeded 1C, and that the warmest January was in 2006. Temperature anomalies are therefore moving to the positive side - consistent with a warming climate - but interannual temp swings or deviations from 1901-2000 average do not show any increase, but are reduced e.g. compared to the 1910-1940 period.