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Messages - Glen Koehler

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Arctic sea ice / Re: "Stupid" Questions :o
« on: June 14, 2019, 07:23:27 PM »
RE:  LeftyLarry
1.   .... "ice comes and goes naturally and man adjusts"
2.  ..."ice been slowly declining since the end of the ice age"   
3.  ...."could a volcanic eruption, bring enough cooling to regrow the lost ice and stop the long term patterns of continued loss"
4. "If all the ice melted and the oceans rose , wouldn’t there still be a huge net gain of habitable land overall?"

    Whether trolling or not, these are questions/assumption many people have, including the U.S. Secretary of State, who recently suggested that people will just move to accomodate a change climate, that climate has always changed, etc.
    What is missing in those perspectives is a sense of scale for time and impacts, along with some basic misunderstandings.

My take on 1-4.
    1.  As others here have noted here and elswhere, it's one thing for a nomadic society of let's say 7,000 humans to move their tents inland in response to millenial rates of change.  Quite another for 7 billion humans with massive infrastructure investments and needs to react to rates of change 10x to 100x faster, thus decadal changes as large as what happend across a 1,000 years in the past. 

     2.  Others here have commented here in more detail.  I'll just add that the "natural" trend has been a gradual cooling since the Holocene peak a few thousand years ago.  Gradual because that cooling was due primarily to natural, = very slow, shift in orbital cycle.  What humans are doing to atmosphere, starting with use of coal as energy source starting ca. 1750, and esp. since 1970 with global increase in fossil fuels, is orders of magnitude more intense and faster than even the most radical climate shifts that led to mass extinctions (90+% of species) in the geologic record.

    3.  Even another Tambora eruption (which caused the "Year without a summer" in New England in 1816) won't protect us from our radical heating of the Earth.  While some climate scientists say the temperature effect is discernible longer than the usually cited 'couple of years', it is temporary nonetheless.  A cooling caused by volcanic emissions into the stratosphere, or a synthetic version through geoengineering, also does nothing to reduce ocean acidification.  Geoengineering to reduce solar energy also introduces major risk of disrupting monsoon and other weather patterns.  "Let's try this, what could go wrong?"  Lots.

    4.  Moving from recently inundated coastlines to newly exposed land formerly under ice caps would bring with it economic and humanitarian destruction of unprecedented scale in the history of human civilization since 4000 B.C.E..  But in addition, just moving the crop belts north isn't going to work.  The temperature bands will move north, but the amount of solar radiation for photosynthesis isn't changing, and the glaciated soil types in central Canada, for example, are not the same as Iowa which used to have 10 feet of top soil in places.  It's going to be tough enough to feed 10 billion people in 2050.  Doing that with degraded ag productivity, which is the consensus projection for global average temperature beyond +1.5-2C (mixed results for lower temp. change) could be impossible. 
      And don't let anybody fool you with the "CO2 fertilization" smoke screen. Increasing CO2 can indeed increase plant growth under controlled conditions where everything else is supplied at optimum (water, fertility, temperature).  Raise CO2 to 450-500ppm in the real world and you won't get any plant growth benefit because those other inputs are not optimized.  Major world food crops are near their thermal maximum now.  Increased temperatures would/will take them over the top of the curve and onto the declining production side even if water supply wasn't an issue.  Moreover, studies find that for the plants that we eat, aka "crops", while they can be grown bigger under higher CO2 with those perfect conditions I talked about above, the density for key nutrients goes down, so a person would have to consume more to get the same amount of nutritional benefit.

    Bottom line - climate disruption is going to kill people.  Lots of them.  The brown and poor people will get hit first, but nobody will escape the consequences of altering the basic life support system of planet Earth.  And by the way, we can't go to Mars.  Think about how many people on Earth it would take to support a colony of a dozen people living inside canisters on Mars.

    So if you love your grandkids (and how could you not) then do everything you can to raise awareness and alarm because this really is a crisis.  It is an unnecessary and avoidable crisis, because we already have the technical capability to produce the energy we need without suicidal continuation of fossil fuel addiction.  The real issue is one of character, long-term wisdom vs. short sighted fear, political will, and mobilization.  Start by refusing to vote for anyone who puts the lives of you, your children, and your grandchildren in mortal danger.

   Sorry for long post.  But you asked and this is the most important issue of human existence.  We have to get this right.  Failure is not an option.

Arctic sea ice / Re: The 2019 melting season
« on: June 11, 2019, 02:03:51 AM »
     Just guessing, but i have to wonder if the CAB number is distorted by fractured mobile ice from peripheral seas getting pushed into the middle.  If so, then the higher CAB value is not necessarily an argument against new record low extent, area or volume this year.  In any case, it will be interesting to see status update after the heat forecast for Siberian coast over the next 10 days.  In other words, I think all bets are still on the table for 2019 melt season. 

     Again, just half-informed guessing, (but if the U.S. President can spew word salad without bothering to read, I should get a shot having at least read up on the topic  -- Don, if your listening I will pay for your subscription to the Arctic Sea Ice Forum). 

    What has me spooked about the Arctic sea ice this year in particular is that the "structural fundamentals" seem to falling apart - dramatic cumulative reduction of multi-year ice; apparent loss of the Beaufort Gyre as a nursery, and potentially it becoming a new killing zone; consistently mild (for the Arctic) winters for most of the years since 2004, and every year starting with 2014; apparently high ice mobility this year; suspicious indications that the polar cell is weakening and that weather patterns that bring warm air into the Arctic may be increasing etc.

   Thus, the threat is much broader and deeper than a temporarily warm forecast.  If I'm wrong about all or any of these, let me know.  I like to be an informed worrier. 

   (PS Slightly off topic, but the June 12-13 GFS shows potential GIS surface melt not far behind the epic July 11 and Aug. 6, 2012 blasts)

    I just read about yet another feedback mechanism I was not previously aware of:
      ' Freshly melted ice ... creates a layer of cold water that protects sea ice above from more melting.   "It isolates the ice from the hot devil water sitting at the bottom waiting to come up" Wagner explains.  Less sea ice means there will be less of that protective cold layer, leading to even more melting. '

     Which got me thinking it would be useful to have an inventory of all the significant reinforcing ("positive") and suppressive ("negative") feedbacks that affect Arctic sea ice.

    I did not find any forum title where this would fit, but this section seems to be the most closely related topic.  It could require its own thread, similar to the Glossary.

Here is the kind of list I have in mind:

Reinforcing feedbacks:
1. Melted ice creates cold layer that insulates remaining ice from warmer subsurface water.  Less ice to melt reduces this insulating layer.  Which leads to even less insulating cold layer water.

2. Less ice leaves darker ocean water with lower albedo, thus energy from solar radiation is absorbed into water instead of reflected.  Warmer water leads to less ice.

3.  Overall, fractured ice is more mobile and thus more susceptible to being exported via Fram Strait or Nares Strait.  There is chance of an ice bridge to block export via Nares Strait with fractured, reduced ice cover.  Increased export results in less multi-year thick ice, and more mobile young ice the next year.

4.  Fractured or thin sea ice floes have more surface area per unit volume and therefore melt at lower temperatures than thicker ice, or larger ice floes.  This leads to less surviving ice the summer to become thicker multi-year ice.

5.  Fractured vs. contiguous ice allows more wave action that interferes with freezing of ice and allows wave action to break ice into smaller pieces less resistant to melt.  Resulting in more fracturing of the remaining ice and even more wave action.

6.  Albedo reduction by replacing ice with dark water leads to warmer water and more energy in the Arctic Ocean system.  That in turn increases frequency, intensity, or both, of cyclones causing wave action that break up ice. Which reduces albedo even further.

7.  Weakening of the Polar Cell results in more frequent occurrence of Arctic Dipole, that increases export of ice out of the Arctic, which lowers Arctic sea ice, which leads to warm Arctic Ocean water, which leads to further weakening of the Polar Cell.  (whew, that's a long chain)

8.  Loss of ice cover weakens the polar cell which in turn allows more incursion of of warm moist air masses from the south into the Arctic, which leads to more weakening of the polar cell.

9.  Weakening of the polar cell allows more cyclonic systems to move into the Arctic.  Those cyclones disrupt the Arctic sea ice, and in doing so further weaken the polar cell.

10.  Younger, thinner ice has higher salt content and thus lower melt temperature.  Therefore it has less chance of surviving the summer melt to become more resistant, thicker multi-year ice.

11.  Reduced snow cover allows earlier spring warm up of Arctic land mass, which results in warmer air flowing onto the Arctic Ocean. This warms the system as a whole, leading to reduced snow cover and earlier snow loss the following year. 

12.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the fall and winter.  More extensive or thicker cloud cover in fall and winter reduces heat loss thus reduces winter refreezing.

13.  Earlier spring warm up of Arctic land mass, results in increased permafrost and land ice thaw, resulting in earlier and more melt water flowing from land into the Arctic Ocean. The meltwater warms the Arctic Ocean and reduces Arctic sea ice.  Which leads to more open water with lower albedo to absorb solar radiation in the summer, increasing summer heat content of the system  More open water allows this heat to escape to moderate winter air temperatures and earlier spring warm up.

14.  Reduction of Arctic sea ice allows increased flow of warmer Pacific or Atlantic water into the Arctic, leading to further decline of Arctic sea ice, leading to more Pacification and Atlantification of the Arctic Ocean.

Compensatory or Suppressive feedbacks:
1.  Ice cover insulates the Arctic Ocean in winter.  With less sea ice cover there is faster energy loss and winter cooling, and thus faster winter ice increase after a lower September minimum extent.

2.  Thin ice grows much faster than thick ice.  Thus faster winter ice increase compensates for thinner ice after a strong melt season. 

3.  More open ocean leads to higher humidity and more extensive or thicker cloud cover over the Arctic Ocean in the summer.  More extensive or thicker cloud cover in summer reflects more solar radiation and thus reduces summer ice melt.


     My wording is no doubt less than perfect for many of these.  Some may be just plain wrong.  Some I just made up!  Maybe I should just find a good book or review article with such a list.  Any suggestions?

   If you think a proposed feedback is incorrect or wrongly stated, it would helpful to have that noted.  But I'm not looking to start multiple debates about which feedbacks are most important. 

      I don't get a commission for each new proposed feedback, so there's no need to get heated.  The planet is hot enough as it is.  These are just suggested entries.  There must be suppressive feedbacks missing from the list.

   I just thought a list would be interesting because I keep finding out about feedbacks I had not previously been aware of. 

Arctic sea ice / Re: The 2019 melting season
« on: June 08, 2019, 09:50:11 PM »
Good explanation of the Arctic Dipole and its interaction with Arctic Sea Ice

Jeff Masters - Weather Underground - the early June Arctic forecast and prospects for summer

Arctic sea ice / Re: The 2019 melting season
« on: June 07, 2019, 04:42:40 AM »
Thanks pccp82. 
My bad.  The image I had in mind was August 6, 2012.

I guess at that point we were discussing the Great Arctic Cyclone of 2012, and I confused that with the great GIS melt day of July 11, 2012.

Looking at that same view for dates on either side of either event, or July-Aug dates in other years, gives some perspective for how out of bounds both events were.   For example the July 21, 2018 image seems to be typical for recent dates in July-August:     

Trying to save face, I went looking for the average 2meter max temp. forecast for Greenland over the next 3, 5 and 10 days, but those are now not showing anywhere near the extent of GIS surface melt shown in the 2012 images.  Update-as of June 9, GFS forecast on Climate Reanalyer shows majority of GIS above freezing on June 13, not too far behind extensive and record breaking surface melt events on July 11 and August 6, 2012.

    While the updated hourly forecasts have no shortage of positive 2M temp anomalies for Greenland over the next 10 days, the max temp hourly forecast also indicates that the area of GIS surface melt next week won't be anywhere close to the July 11 and August 6, 2012 images.  So either I just blew it with respect to Greenland surface melt coming next week, or the 10-day outlook changed.    ***My mistake in previous post was misunderstanding that the 10-day Greenland surface temp reading was not the average for a 10-day period, but the average of hourly values for the 10th day, i.e. a single day reading not a 10-day average.  As noted above, updated forecast shows that June 13 (which was the 10th day noted in original post) is forecast to have an extent of surface melt similar to record-setting events in 2012.

    That said, the current hourly forecasts still shows the high precipitable water, the persistent crazy high temp. anomalies stretching across long arc of northern Siberia, and for much of the forecast period, also on the North American side.  The forecast shows snow cover depth north of Greenland essentially gone by June 10 2019 (scale is cm).

vs. June 10 in 2018. 

It took until June 22, 2018 for snow depth image to match the June 10, 2019 forecast.  While that does not seem like a cataclysmic difference to my untrained eye, a 12 day earlier loss of snow cover with the sun at near maximum height, combined with many blue sky hours also in the forecast, does seem notable in terms of insolation.   

Enough covering my tracks.  What I definitely did get right and did not exaggerate was an Arctic weather expert ringing the alarm bell about the forecast as it appeared at that time, and the Arctic sea ice situation overall.  Vote climate.

Arctic sea ice / Re: The 2019 melting season
« on: June 07, 2019, 02:08:20 AM »
    A friend and colleague who is a PhD climate scientist, and whose work is regularly cited in this forum ... (but I'll leave his name out of it, even though Sean said it was OK to cite him... ooops)

    ....and who has watched Arctic weather for many years, brought the subject up at the end of a day-job phone conversation earlier this week.  He said it's hair raising, that he's never seen anything like what (as of Tue. June 4), was forecast for the next 10 days, esp. the latter part of that forecast as we head into mid-June.  One that I was not previously aware of was the amount of precipitable water in the air masses flowing into the Arctic.  e.g.

  And the story is not limited to the Arctic sea ice.

    One striking example as he walked me through a hall of horrors of forecast images was an image of the infamous ~97% Greenland surface-melt day (edit: days in July & August 2012.  The one that was so bizarre that NASA seriously thought the satellite sensor must have gone bad because such a reading was unprecedented and unfathomable.  (And which my friend on the phone said GFS foresaw at least a week in advance, just to defend the underloved GFS a bit.  BTW - GFS is getting the FV3 upgrade June 24!). 

     Then he took me to the 10-day 10th day Greenland surface temp image for this JUNE   And while not covering the almost the entire GIS as happened in the 2012 blasts, the 2019 forecast image was for a 10-day average, not a single day, and the 2019 image was for mid-June, not July or August.

    Another striking image was the projected very early 2019 timing for loss of ice/snow cover north of Greenland.

    While I'm a long time climate hawk and ASIB watcher, not being a climate scientist and being only a recent ASIF lurker with a post count even smaller then Trump's tiny little extremities (I'm talking about his hands, jeesh, get your mind out of the gutter!), it's been difficult for me to interpret the "contextual significance" for all the recent hubub about the 2019 melt season. 

     So for others of you watching the discussion from that perspective, the point of this post is that a PhD climate scientist with expertise and experience in Arctic weather (while acknowledging that forecasts can change, that June is not the whole summer, and that the Arctic is fickle) is having his own "Holy Cow" moments this week, to put it politely.  Stay tuned.  And vote climate. 

Arctic sea ice / Re: Basic questions about melting physics
« on: May 30, 2019, 03:28:47 PM »
     Simpler framing of the original question makes the answer easier to see.
Original mystery (to me at least) was why wasn't PIOMAS volume decreasing in sync  with loss of old think ice?

    My new dope-slap-forehead observation - winter maximums have declined, but not as much as summer minimums (maxima, minima for those of you who remember 7th grade Latin).  Thus it is clear that winter refreeze has increased along with declining summer minima.  Not enough to fully compensate for increased summer losses, but enough to reduce their impact on winter maxima.
   As helpfully pointed out by Oren and others, that is indeed the case.  As to why winter ice gain increases with declining summer minima, two mechanisms are
1) thinner ice is able to increase thickness faster, and
2) ice cover acts as an insulator, thus less insulation means faster cooling in the following fall/winter. 
     There may be other mechanisms in addition to 1 and 2 (changes in cloud cover or wind patterns?).  And within 1 and 2 there are more detailed explanations for how/why they work.

   So nothing new here in this post!  I just thought anybody who was also puzzled by the original question, lack of 1:1 correlation between dramatic loss of older, thick ice, and the more subtle (but consistent trend) of PIOMAS ice volumes would find a bit of catch up and summary useful. 

   Two particularly interesting and useful points that arose -
    a) thick ice does not necessarily mean old ice.  Thinner fractured ice floes are more susceptible to being transported by wind or currents into thicker piles.
   b) salinity differences account for why older ice is more resistant to melt; and younger, saltier ice is less resistant to melt (though not everybody seems to agree about the chemistry at the molecular level).

     NOAA's new FV3GFS replacement/upgrade for GFS scheduled to go live on June 24.  This is 3rd scheduled operational date, first delayed by shutdown, then they found a temperature bias issue which needed correction.  I think this time they will actually do it. 

     FV3GFS 1.0 not expected to provide better accuracy right away, but the new platform provides a better foundation for development.  Original plan call for extending hourly runs at 13km resolution from current 10 day limit out to 16 days.  (Current GFS runs at 35km resolution and 3-hour time steps for days 11-16).

   New model will make better use of the awesome new GOES East and West satellites.  (Think color TV vs B&W still pictures).

   A version 2.0 of FV3GFS planned for a year after 1.0 version.  2.0 will bring new physics package.  And about a year after that, timeline shows a possible resolution improvement down to 9km.  Improved ensemble forecast system scheduled for FY2020. No mention of seasonal forecasting until at least FY2023. 

   This all driven by playing catch-up with ECMWF that called Superstorm Sandy path change a day earlier than GFS.  Of ECMWF isn't standing still either.  This is the kind of arms race we need.

Arctic sea ice / Re: The 2019 melting season
« on: May 26, 2019, 11:00:55 PM »
     Bottom melting is a known driver but seems to get little monitoring.

    1)  In addition to temperature, cloud cover, insolation, wind, ice extent/area, ice thickness, ice age, ice condition, melt pond momentum, and land attachment, does the amount and temperature of Atlantic current inflow act as a driving factor for melt? 

    2)  Are there tracking and forecast maps/summaries for Atlantic inflow volume and temperature to use as predictors?  Known historical patterns or correlations with September minimum.
    3) Ditto Pacific inflow, but my understanding is that Atlantic inflow is a stronger influence.

    4)  Exploring my ignorance out to its edge, it seems like there might be a trend for cloudier Arctic summer weather with increased open water.   To the extent that there is skill, multi-month June-September Arctic weather outlook would be interesting.
PS #1088 JDAllen - interesting point about melt ponds not just changing albedo but also serving to conduct air temperature into ice.  Never heard that before but it makes sense.

Test question "What is causing Arctic Sea Ice loss" - 3 letter acronym.  Stumped me.


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