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Messages - Juan C. García

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1
Arctic sea ice / Re: Global sea ice area and extent data
« on: May 24, 2019, 11:17:48 AM »
Two more days and everything will be back to normal again.

Right?

2
Permafrost / Re: Permafrost general science thread
« on: May 23, 2019, 01:59:44 PM »
Widespread Permafrost Degradation Seen In High Arctic Terrain
https://phys.org/news/2019-05-widespread-permafrost-degradation-high-arctic.html

A McGill-led study published recently in Environmental Research Letters presents close to 30 years of aerial surveys and extensive ground mapping of the Eureka Sound Lowlands area of Ellesmere and Axel Heiberg Islands located at approximately 80 °N. The research focuses on a particular landform (known as a retrogressive thaw slump) that develops as the ice within the permafrost melts and the land slips down in a horseshoe-shaped feature. The presence of these landforms is well documented in the low Arctic.

... "Our study suggests that the warming climate in the high Arctic, and more specifically the increases in summer air temperatures that we have seen in recent years, are initiating widespread changes in the landscape," says Melissa Ward Jones, the study's lead author and a Ph.D. candidate in McGill's Department of Geography.



The research team noted that:

- There has been a widespread development of retrogressive thaw slumps in high Arctic polar deserts over a short period, particularly during the unusually warm summers of 2011, 2012 and 2015;

- That the absence of vegetation and layers of organic soil in these polar deserts make permafrost in the area particularly vulnerable to increases in summer air temperatures;

- Despite its relatively short duration, the thaw season (which lasts for just 3-6 weeks a year) initially drives the development of slumps and their later expansion in size, as their headwall retreats; and

- Over a period of a few years after the initiation of slumps, study results suggest various factors related to terrain (e.g. slope) become more important than air temperature in maintaining active slumps


Open Access: Melissa K Ward Jones et al, Rapid initialization of retrogressive thaw slumps in the Canadian high Arctic and their response to climate and terrain factors, Environmental Research Letters (2019)

4
Arctic sea ice / Re: The 2019 melting season
« on: May 22, 2019, 05:01:26 AM »
May 17-21.

5
Arctic sea ice / Re: The 2019 melting season
« on: May 22, 2019, 03:59:51 AM »
Quote
be cause: can only guestimate area that heads out of the basin but it is a lot
Right. Wind-driven ice motion has been extraordinary this freeze/melt season. By translocating thicker, older ice into zones that will melt out later in the summer, or exporting ice altogether out of the basin via the Fram, Nares and Svalbard-FJL chain plus blocking Kara Sea ice on the import side, wind-driven ice motion may challenge conventional bottom and top melt this year as the leading ice volume loss mechanism.

The first image below shows  on mid-basin Atlantic-side feature drift (boundary between old and new ice) over the the last 195 days using twenty-day contours.

A similar area of ice ahead of the front has been (or will be if wind patterns keeps up) irreversibly displaced out of the basin. This area can be measured, not adjusting for compression or extension, by lifting geo-referenced Ascat images onto Google Earth Pro for its ellipsoidal (WGS84) area and length calculations (2nd image shows the 7.109 million sq km polygon of relevant Arctic Ocean.

Wx predictions are the proverbial drunk looking for her car keys under the street lamp because the light is better there -- winds thousands of meters above the ice are easier to predict than the 0m winds, yet only the latter actually move the ice pack (by coupling to pressure ridges and floe edges rather than flat pan).

You can see this on any given day by comparing ice motion vectors observed by OSISAF/NSIDC to winds GFS or ECMWF are showing, before or after reanalysis (3rd image). Surface currents are negligible (or as oceanographer R Woodward notes, induced by ice keels) outside the intake funnels of the Nares and Fram and inconsistent Bering Strait flows to/from the Chukchi. Note the ice pack has a certain amount of mechanical rigidity, leading to cohesive motion despite a heterogeneous stress field.

The Arctic Ocean is seriously 'under-instrumented', meaning models have never had sufficient calibration or feedback guidance. On the rare instances an instrumented ship has been out there in May (eg N-ICE spring 2015), measurements departed markedly even from nearby land stations like Ny-Ålesund. However nobody ever fixed a weather model or reanalysis based on a basin instrument account.

Help is in sight (with a 2-3 year delay?): this Sept, AWI's Polarstern will drift for a full year on a thick Siberian-side floe (lol !) to collect "direct in-situ observations of the climate processes that couple the atmosphere, ocean, sea ice, bio-geochemistry and ecosystem ... to enhance understanding of the regional and global consequences of Arctic climate change and sea-ice loss and improve weather and climate predictions. https://www.mosaic-expedition.org

This won't be meagre point weather and ice properties because they are going out to a 50 km swath radius on both sides of the drift track. The 4th image shows a hypothetic drift trajectory. They'd have been home early this year whereas in 2017/18 the ship would hardly have moved in the hoped-for direction:

233 days of anti-transpolar drift 2017-2018.mp4
https://forum.arctic-sea-ice.net/index.php/topic,2278.msg155398.html#msg155398

The Oden made a remarkable observation of open water at the north pole on 25 Aug 18, photographing a walrus there, messing with a research sled. Ask yourself how much open water there had to be regionally for a walrus to swim to the NP on that date and when it last ate: the water is 4,087 m deep whereas the deepest walrus dive ever recorded is 500m.

This and a few little things like ice thickness went seriously under-reported (except by Jim Hunt and twitter). This has really got to change -- scientists chewing on their cud for years (buffing their journal articles) while leaving everyone else in the dark.

I had an identical experience trying to get even the most mundane CTD casts from the Polarstern when by great good fortune they were able to reach the Weddell Sea during that unprecedented reversal of the Fram in Feb 18 attributed to a sudden stratospheric warming. A cr*ppy article by another research group ensued who also couldn't get the data. Where is the public benefit in  hoarding?

6
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 21, 2019, 02:12:00 PM »
NSIDC NT sea ice extent and area in the Arctic Basin (where most of the last summer ice will be) continue to drop fast.

7
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 19, 2019, 05:47:08 AM »
May 18th, 2019:
     11,374,861 km2, a drop of -46,238 km2.
     2019 is 2nd lowest on record.

8
Arctic sea ice / Re: The 2019 melting season
« on: May 18, 2019, 12:01:27 PM »
There is max temperature in the last image.
A quibble...

I think I am right in saying that the GFS maximum (and minimum) temperature images are a bit deceiving, in that even if the forecast is 100% correct, there will not be a date/time when the image is a reality.

For the 5 day image shown, I think the image shows the maximum temperature for each element of the grid over the next 5 days. So one place might be at maximum today, another in 3 days time, and so on.  You can tell this from the image. Alaska cannot be at maximum temperature at the same time as Norway - if Alaska is basking in the late afternoon sun, Norway is freezing in the early early hours before dawn.

Thus the maximum image exaggerates the heat, the minimum image exaggerates the cold.

Mind you, it still looks like the Central Arctic sea ice is on the move and in serious grief..

9
Arctic sea ice / Re: The 2019 melting season
« on: May 17, 2019, 11:47:49 AM »
60 hour loop of the Beaufort. May 14 12Z  - May 17 0Z.
 (Requires a click)

Second attachment is the ECMWF forecast. The tight pressure gradient north of Alaska is progged to persist another 5 days or so, resulting in 20-30 knot easterly winds.

10
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 17, 2019, 09:23:59 AM »


At the moment still little reason to suppose sea ice loss will accelerate further.

So..just in the interest of keeping it fresh...what variables are you taking into consideration when you suggest that there is no reason to suppose sea ice loss will accelerate?

For clarification, I'm grateful for the effort that people like you put into providing the data that you do. Thank you!!

But I'm also coming from a perspective that we're heading for an inevitable BOE / climate apocalypse in coming decades and that most people here are just here to witness that and share the experience.

There's a balance of people who are seeing the potential for short-term demise and those like yourself who are saying...not yet.

Anyway ..I'm curious to know what variables you consider when there are differences of opinion. I sincerely want to learn.
My statement referred to current forecast period of around 10 days simply from looking at fairly low +ve temperature anomalies and current fairly strong extent loss. i think it is far too early to look at the end of season minimum with any confidence at all. Others disagree.

Thanks for the reply. As someone trying to learn, each piece helps. My inference is that you see atmospheric temperature as the dominant variable.

It would be interest to get some kind of sense of how people rank the various variables.

As a newbie, I would guess water temperature is at least up there with atmospheric temperature . Sunlight has been pointed out. The spin which brings ice to Fram seems important. Nares being open with a steady throughput. Wind. The thickness of the ice. The level of surface fracturing.

Thanks for your patience. I'm just trying to get oriented. Asking questions helps.

11
Consequences / Re: Places becoming less livable
« on: May 16, 2019, 10:04:06 PM »
The sargassum problem is way bigger than just Mexican beaches. It affects wide areas of the caribbean. I saw the problem first hand last year, and it was astonishing to see nature's capacity for disruption.

For anyone interested this website is a great resource for tracking sargassum blooms:

http://seas-forecast.com/

12
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 16, 2019, 06:31:54 AM »
Bimonthly BOE evaluation

May 15 extent was 11,568,100 km^2. With on average 121 days to go until the end of the melt season on September 13th, we now require a daily drop of -87,323 km^2 for a BOE to occur. (See Attachment 1).

There have been many days of below average melt, and several days of above average melt. Total extent loss thus far in May is -739,276 km^2. And total extent loss so far this season is -2,705,021 km^2. This has resulted in the current average daily drop of -42,266 km^2. If the month of May ended today, this would the 3rd fastest daily loss from maximum to the end of May (behind 2010 at a whopping -57,318 km^2 per day, and 2014 at -42,541 km^2 per day). (See Attachment 2).

Looking only at the month of May (so far), we have averaged -49,285 km^2 per day. This average daily drop places May 2019 as 8th out of 13 (2007-2019) in average daily May melt (See Attachment 3).
Although we still have 16 days to go this month, and many of the ASIF gods are becoming worried about the high pressure setup forecast by GFS.

No 2nd post for mid monthlies, don't have the data calculated and I am traveling so even this post was unexpected for me.

Edit: was tired and missed 2,000 km^2 so the averages will be slightly lower. My mistake.

13
Arctic sea ice / Re: The 2019 melting season
« on: May 15, 2019, 11:18:30 PM »
I have some analysis - nothing too spectacular - at the end of PIOMAS May 2019 that I've just posted on the ASIB. Two images below from that blog post, ECMWF weather forecast and Beaufort yesterday vs a week later in 2016:

14
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 15, 2019, 11:14:52 PM »
PIOMAS May 2019 is up on the ASIB. If there's a mid-month update form the PSC today or tomorrow, I'll append it to the blog post.

15
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: May 14, 2019, 08:52:40 PM »
@Tor - Thanks!  We will see.



  Consequently, he is hesitant to make any new ice-free projections.

He's hesitant to make any specific ice-free projections, but he does think that it will be sooner than 2030.

No, he never said that.  Only that it might.

Well, if you start from right here in the video - https://youtu.be/yoy4U7MGIdo?t=1103

Here's some of the dialogue -

Wiselaw:
"There are some publications now, peer-reviewed publications which are using the global climate and Earth system models and, uh, hand picked some of them for their better representation of the Arctic ice area and they provided the estimate of ice disappearance roughly between 2030 and 2040."

Guy:
"And what do you think about that?"

Wiselaw:
"I would still think that it might happen sooner than that but I would hesitate to provide a specific date basically because the system is so complex and so nonlinear."


¯\_(ツ)_/¯


17
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: May 12, 2019, 08:42:56 PM »
Airborne NASA Scientists Just Filmed Something Troubling In Greenland
https://mashable.com/article/greenland-melt-2019-climate-change/



Scientists aboard a NASA airplane swooped over some of Greenland's largest glaciers on Monday, spotting melted ice and raging rivers.

It's significant, because though it's not nearly summer, large blue ponds have already formed on the icy ground. NASA’s Operation IceBridge researchers observed this as part of their mission to watch for changes in Earth’s giant masses of polar ice. Greenland, in particular, has been melting at an accelerated rate for some two decades.

"Although the story of the summer of 2019 in Greenland hasn’t yet been written, it's starting on a worrying note," said Joe MacGregor, the project scientist for Operation IceBridge.

While such profound early season melting isn't unprecedented, typically these melt ponds form in late May to early June, explained MacGregor. This spring, there's one obvious culprit: really warm temperatures. Last week in Greenland — one of the coldest parts on Earth — temperatures measured in the upper 50s to low 60s Fahrenheit, he said.

MacGregor is on land in the U.S., but his IceBridge colleague, glaciologist Brooke Medley, captured footage of the early melt creating big pools of water, seen below.


https://twitter.com/DrBrookeMedley/status/1125873350448906240

https://twitter.com/i/videos/1125873350448906240

@NASA #IceBridge ✈ observed surface melt north of Jakobshavn ... While the blue water is breathtaking, the early onset of melt over Greenland is concerning for Earth ... "Concerning" - what a uselessly weak verb. Totally fails to convey the gravity of these images ... meltwater ponds also visible on Landsat/Sentinel/Modis pics...caused by record breaking warmth since end of April (Kangerlussuaq up to19deg C).


A mosaic from the CAMBOT instrument on #IceBridge shows a melt pond with surface rippling, as seen on Sunday's flight.



From Sunday's #IceBridge flight: Emerald green ponds weave around ice and debris near the terminus of Russell Glacier, which is showing signs of an early onset into the melt season

"The melt has the potential to accelerate," said MacGregor.

------------------------------------

Tsunami Signals to Measure Glacier Calving in Greenland
https://www.sciencedaily.com/releases/2019/05/190508093748.htm

Scientists have employed a new method utilizing tsunami signals to calculate the calving magnitude of an ocean-terminating glacier in northwestern Greenland, uncovering correlations between calving flux and environmental factors such as air temperature, ice speed, and ocean tides.

18
Arctic sea ice / Re: The 2019 melting season
« on: May 12, 2019, 02:09:02 AM »
Worldview aqua modis caa and nth greenland today.

 cheers Uniquorn .. I looked back to 11.05.2007 on Worldview and saw almost the same pattern of cracks . I was wondering if an active Nares could be more important than anyone has imagined ? It is as if the Arctic's strength .. the Canadian - Greenland - Pole triangle is compromised .. b.c.

19
Arctic sea ice / Re: The 2019 melting season
« on: May 11, 2019, 10:07:09 PM »
Mercator (model) salinity 0m and 34m indicating a surge of atlantic water around north greenland combined with returning atlantic water from the north. The surge may be temporary, the other isn't.

The CAA coast isn't looking too good either. https://go.nasa.gov/2DYOu2z
@b_l nice, but there are many repeat frames in that ani

20
Greenland and Arctic Circle / Re: The 'Very Big Chunk' poll
« on: May 11, 2019, 07:37:48 PM »
Latest Sentinel image. I have never seen the Lincoln look like this:

21
Greenland and Arctic Circle / Re: The 'Very Big Chunk' poll
« on: May 11, 2019, 07:20:02 PM »
I really want this plucky floe to save the Lincoln sea single handedly. It's only a flesh wound ;)
replaced image with today's aqua, terra, viirs(suomi/npp)
This method does appear to show tidal movement. By the way, does this rule out 'not!' or does it have to stay put for 24hrs ?
edit: added this morning's image to the animation. It's a shame it's so warm there today.

22
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 09, 2019, 06:57:03 PM »
NSIDC NT sea ice extent and area in the Arctic Basin (you know what I mean) are now both below anything previously on the 8th of May.

23
Arctic sea ice / Re: The 2019 melting season
« on: May 09, 2019, 02:38:30 PM »
Not much warmth in the pacific inflow as yet, just salinity. Atlantic water more dominant in the Laptev than last year (according to the model) Mercator salinity 0m, mar1-may7
That's basically where the Atlantic waters turn the corner after flowing along the Eastern continental shelf of the Nansen basin, heading back north. I wonder if there is a) shoaling causing deeper waters to rise and b) if that water is warmer than usual.
I don't think they rise to the surface. That area was the last to melt last year. The ess arm has been stretched and refractured all last freezing season. It's probably just thin ice.
salinity/ascat here: https://forum.arctic-sea-ice.net/index.php/topic,2417.msg193927.html#msg193927
bathymetry/ascat: https://forum.arctic-sea-ice.net/index.php/topic,2417.msg193927.html#msg193927
Perhaps it hasn't really been that cold on the pacific side last freezing season.
polarportal ice surface temperature, sep24-may8
edit - forgot scale

24
Arctic sea ice / Re: The 2019 melting season
« on: May 09, 2019, 03:08:03 AM »
Looking at Wipneus' chart of the ESS ice area since 2012, it seems cracking/fragmentation events with the resulting temporary loss of area are common, but that the first sustained area drop that did not refreeze happened in 2017, in mid-May.
Should the ESS continue losing area rather than refreeze, this year could be even earlier than 2017.

25
Consequences / Re: World of 2030
« on: May 09, 2019, 03:03:43 AM »
A fact is described as a statement that can be verified or proved to be true. Opinion is an expression of judgment or belief about something. Fact relies on observation or research while opinion is based on assumption. The fact is an objective reality whereas opinion is a subjective statement.


26
Permafrost / Re: Arctic Methane Release
« on: May 07, 2019, 11:15:16 PM »
This was mentioned in the Greenland thread.  As I thought about it, I wondered if there would be a positive feedback loop with the methane release:

Greenland melts causing less gravitational pull on the waters near Greenland, the sea level drops lower, which results in the warmer surface water being closer to the seabed, then seabed warms faster, which releases methane, causing Greenland to melt faster (and repeat!?!)

https://climate.nasa.gov/news/2626/evidence-of-sea-level-fingerprints/
A very good question. If the seabed becomes shallower even this alone could cause some methane release due to removal of water pressure, plus a shorter water column.
Some of the continental shelf could become completely exposed, depending on the bathymetry near Greenland. Again, methane implications.
I should point out that this is a very long process, and could play over centuries.

27
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: May 06, 2019, 03:31:55 PM »
The gravity effect seems reasonable to me.  Link to NASA video on sea level changes since 2002:

https://climate.nasa.gov/news/2626/evidence-of-sea-level-fingerprints/
 

28
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 05, 2019, 02:03:09 PM »
NSIDC NT sea ice extent and area in the Basin (Beaufort, Chukchi, ESS, Laptev and Cental Basin) continue to drop fast. Area is below anything before in the first days of May.

29
Arctic sea ice / Re: The 2019 melting season
« on: May 05, 2019, 07:50:55 AM »
April 29 - May 4.

30
Greenland and Arctic Circle / Re: What's new in Greenland?
« on: May 04, 2019, 06:28:40 PM »
I made some glacier size comparison charts featuring Greenland & Antarctic Glaciers. I hope it better visualizes how much ice is exposed to ocean water than a Bedrock map. The charts shows the dimensions of the glacier front. Where the x-axis is the glacier width and the y-axis is the glacier height.

https://cryospherecomputing.tk/Glacier-size

31
Arctic sea ice / Re: Latest PIOMAS update (May 2019)
« on: May 04, 2019, 02:39:12 PM »
Thickness map for 30th of April 2019, compared with previous years and the differences.

32
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: May 04, 2019, 02:19:03 PM »
The East Siberian Sea continues to los area at a rate of knots.
Now 3 weeks ahead of the 2010's average, and 6 weeks ahead of 2018.

The Beaufort also showing signs of joining in.

Getting quite late in the season for a total refreeze? Much depends on how long the above average temperatures and winds favourable for open water expansion last.

34
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: May 03, 2019, 08:24:11 PM »
DMI should declare 'open season' on the melting season tomorrow as their criteria for 5% or greater melt extent for three consecutive days is all but assured to be met.

They heard you  :)
https://www.dmi.dk/?id=1042 (in danish)
http://polarportal.dk/en/news/news/greenland-melt-season-officially-starts-almost-a-month-early/
(in english)

35
Arctic sea ice / Re: The 2019 melting season
« on: May 03, 2019, 06:33:37 AM »
<snippage>
Persistent northerlies has meant the pack is pushed against the north coast of island of Spizbergen - something that hasnt happened since July 2017.
It appears Fram export is ramping up in tandem with this.  Just the last few days it appears the ice has been accelerating through it.  The northerlies no doubt are contributing to this.

Velocities appear to be approaching 1-1.5KPH.  At current concentrations, that's upwards of 10,000KM2 a day of the thickest ice in the region past the point of no return.

36
Ken,

While I appreciate your perspective, it seems to be out of step with reality.

The first image below was recently tweeted by Greta Thunberg showing that pathways required to limit warming to 1.5C (see below). All realistic pathways rely on negative emissions, which will either require massive reforestation (which means limiting and reversing urban sprawl and other development), or carbon capture technology powered by non-emitting energy sources we currently do not have.

The second set of three images comes from Glen Peters, Research Director at the Centre for International Climate Research. It shows the required emissions reductions for 2C, or to meet the Paris agreement. It shows what is required by the rest of the world if India, China, the Euro zone and the US achieve emissions reductions consistent with Paris.

Caption: a) Global warming under 2 °C with a 75% probability, with negligible development of engineered sinks and land use change (LUC); (b) global warming under 2 °C with a 66% probability and negligible development in engineered sinks and LUC; and (c) global warming under 2 °C with a 75% probability, and with scalable development in engineered sinks and LUC.)

Please note three things, which Glen Peters also recognizes: 1) As far as we know, passing 2C of warming will make it very difficult to avoid catastrophic climate change; 2) The image assumes 2017 as a turnaround date. This did not happen (nor is it expected to happen this year), making the required reductions even more significant; 3) It is likely that the emissions pathways laid out are optimistic, since they rely on IPCC projections which have been proven to understate the risks; and it has recently been confirmed that emissions from the tar sands are up to 64% higher than reported (see https://www.cbc.ca/news/technology/oilsands-carbon-emissions-study-1.5106809?__vfz=medium%3Dsharebar). If this is the case in Canada we can expect that emissions are also higher than reported elsewhere in the world, meaning that we have already emitted more (and potentially much more) than assumed by these pathways.

Last month a "massive analysis" came out stating all of the above in a different way:

"The massive analysis shows that meeting the 2C target is exceptionally difficult in all but the most optimistic climate scenarios. One pathway is to immediately and aggressively pursue carbon-neutral energy production by 2030 and hope that the atmosphere's sensitivity to carbon emissions is relatively low, according to the study. If climate sensitivity is not low, the window to a tolerable future narrows and in some scenarios, may already be closed.

... If the climate sensitivity is greater than 3 Kelvin (median of assumed distribution), the pathway to a tolerable future is likely already closed."

Subsequent to this massive analysis, the preliminary results from the new generation of climate models -- which will inform the next IPCC report -- began to be released.

"Early results suggest ECS values from some of the new CMIP6 climate models are higher than previous estimates, with early numbers being reported between 2.8C and 5.8C. This compares with the previous coupled model intercomparison project (CMIP5), which reported values between 2.1C to 4.7C. The IPCC’s fifth assessment report (AR5) assessed ECS to be “likely” in the range 1.5C to 4.5C and “very unlikely” greater than 6C. (These terms are defined using the IPCC methodology.)"

https://www.carbonbrief.org/guest-post-why-results-from-the-next-generation-of-climate-models-matter

The median given by AR5 was 3C (or 3K). The difference with the new models is represented graphically below in the third image.

As we are now seeing the new models are giving a value of ECS ranging from 2.8C to 5.8C, with a median of 4.3C.

So what is to be gained by assuming the lower risk scenarios, when, should you be wrong -- as I would suggest the overwhelming amount of evidence now indicates -- we expose ourselves to a tremendous amount of risk?

This seems to me the underlying message of ASLR's posts.


37
Consequences / Re: World of 2030
« on: April 29, 2019, 02:12:10 PM »
My prediction for 2030 is that people that were predicting slow, easily adaptable climate change will pretend they never said such things. It is likely they tell everyone they have been warning us about the incoming doom for decades. Most of them will immediately forgive themselves for slowing down action against climate change.

Only a few of them will remember their part in making us unprepared and accept the responsibility.

38
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: April 29, 2019, 11:58:06 AM »
The (relatively) warm weather in Greenland is reflected in a further spike in the melt extent:


39
Arctic sea ice / Re: The 2019 melting season
« on: April 29, 2019, 10:41:56 AM »
something tells me we're in for a nasty drop from day 2-5

Looks like you were right, JAXA reported a 112K drop for the 28th.

Renewed signs of general movement from Chukchi to the Barents. This is what I fear the most, especially considering the forecasts for a dipole-like setup in the next few days. The longer the movement continues without change the thicker the ice that gets exported and lost.

I'll second that. The high pressure over the Beaufort just keeps going, and we're now entering May...

40
Arctic sea ice / Re: The 2019 melting season
« on: April 29, 2019, 10:04:09 AM »
April 23-28.

The Lena wakes up on time.
Renewed signs of general movement from Chukchi to the Barents. This is what I fear the most, especially considering the forecasts for a dipole-like setup in the next few days. The longer the movement continues without change the thicker the ice that gets exported and lost.

41
Consequences / Re: Hurricane Season 2019
« on: April 29, 2019, 09:51:58 AM »
Mozambique Situation 'Worse than Thought': UN Agency
https://www.bbc.com/news/world-africa-48087906

The situation in northern Mozambique is worse than thought, a UN spokesman says, days after Cyclone Kenneth ravaged the country.

The system struck the Africa nation on Thursday with winds of 220km/h (140mph) which flattened whole villages.

Around 700,000 people are now thought to be at risk in the area as torrential rains continue.

Pemba, regional capital of Cabo Delgado state, has experienced more than 2m (6.5ft) of rain and flooding.


"We are very worried because, according to the forecasts, heavy rain is expected for the next four days," Deborah Nguyen, UN World Food Programme spokeswoman, told AFP news agency.

"We expect the rainfall to be twice as much as that which accompanied Cyclone Idai," she added.

Landslides are a growing worry in the city's Mahate neighbourhood, regional Ocha authorities said, while in the Natite neighbourhood houses have started to collapse.

42
Consequences / Re: Hurricane Season 2019
« on: April 28, 2019, 03:21:36 AM »
After Cyclone Kenneth, Mozambique hit by rain and winds 
https://dw.com/en/after-cyclone-kenneth-mozambique-hit-by-rain-and-winds/a-48507946

Heavy rain and winds across northern Mozambique on Friday brought warnings from the UN of "massive flooding" to come in the next few days as Cyclone Kenneth moves slowly inland over northern Mozambique.

The UN World Food Programme (WFP) said it was possible 600 millimeters (almost 24 inches) of rain could fall over the next few days in some areas. This would be double the amount of rain that fell on the central city of Beira during the cyclone which hit in March.

The storm hit Mozambique just as crops including cotton, maize, soybeans and millet were about to be harvested.
It was the first storm to make landfall over the northern coast's Cabo Delgado province in 60 years.

43
As some has noted earlier in this thread, RCP2.6 is no longer attainable.
https://news.agu.org/press-release/new-studies-highlight-challenge-of-meeting-paris-agreement-climate-goals/
A short quote and snipping out the top image from the second study with Peters.
Quote
Stone, with the National Institute of Water and Atmospheric Research, said Peters’ study shows no one country can slip up in the goal to meet climate goals.

“It is hard to argue against their conclusion that we need to start seriously considering options such as the deployment of solar geoengineering, with all of the risks that entails, if the world is serious about achieving the Paris Agreement goals,” he said.

44
Policy and solutions / Re: Extinction Rebellion
« on: April 27, 2019, 07:29:01 AM »
George Harrison's 1981 album SOMEWHERE IN ENGLAND.

"We've got to save the world. Someone else may want to use it."


45
This study from 2018 indicates that the West Antarctic Ice sheet wont disintegrate if we can reduce emissions to the RCP 2.6 scenario.

https://www.the-cryosphere-discuss.net/tc-2018-220/tc-2018-220.pdf

Quote
Uncertainty quantification of the multi-centennial response of the
Antarctic Ice Sheet to climate change

Kevin Bulthuis, Maarten Arnst, Sainan Sun, and Frank Pattyn

Abstract. Ice loss from the Antarctic ice sheet (AIS) is expected to become the major contributor to sea-level rise in the next centuries. Projections of the AIS response to climate change based on numerical ice-sheet models remain challenging to establish due to the complexity of physical processes involved in ice-sheet dynamics, including instability mechanisms that can destabilise marine sectors with retrograde slopes. Moreover, uncertainties in ice-sheet models limit the ability to provide accurate sea-level rise 5 projections. Here, we apply probabilistic methods to a hybrid ice-sheet model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology and bedrock relaxation, on the continental response of the Antarctic ice sheet to climate change over the next millennium. We provide probabilistic projections of sea-level rise and grounding-line retreat and we carry out stochastic sensitivity analyses to determine the most influential sources of uncertainty. We find that all 10 sources of uncertainty, except perhaps the bedrock relaxation times, contribute to the uncertainty in the projections. We show that the sensitivity of the projections to uncertainties increases and the contribution of the uncertainty in sub-shelf melting to the uncertainty in the projections becomes more and more dominant as the scenario gets warmer. We show that the significance of the AIS contribution to sea-level rise is controlled by marine ice-sheet instability (MISI) in marine basins, with the biggest contribution stemming from the more vulnerable West Antarctic ice sheet. We find that, irrespectively of parametric 15 uncertainty, the strongly mitigated RCP 2.6 scenario prevents the collapse of theWest Antarctic ice sheet, that in both RCP 4.5 and RCP 6.0 scenarios the occurrence of MISI in marine basins is more sensitive to parametric uncertainty and that, almost irrespectively of parametric uncertainty, RCP 8.5 triggers the collapse of the West Antarctic ice sheet.

46
Greenland and Arctic Circle / Re: The Nares Strait thread
« on: April 26, 2019, 09:05:56 PM »
Hello all, thought I would introduce myself.  I've been following this thread with a great deal of curiosity since I found it about a month ago, in lieu of the great breakup of March 20th.  I'm the operator of the Dr. Neil Trivett Global Atmosphere Watch Observatory in Alert, NU, so I've been watching all of this ice movement first-hand.  It's been a very different winter this year with a lot of fog and precipitation thanks to all the open water immediately offshore.

Here's a view a little different from the satellite imagery you usually get to see, taken a moment ago from the top of our instrument tower at the lab.

- Kevin

47
Arctic sea ice / Re: The 2019 melting season
« on: April 26, 2019, 10:35:21 AM »
Combining 2 images - April 25th on the left, and April 21st on the right to take out cloud -  you can see the broken ice is joined together now. I looked back in the years, and don't see this any other year doing that at this time of year. 2010 comes close on May 4th. A cracked and fractured icesheet from Nares to Fram now.
Agreed. edit: I should add that it is still cold enough for refreeze in those fractures, but the drift is too fast to make much difference.
Worldview terra modis, north greenland, apr8-24. Contrast enhanced to show fractures. 7days/sec.
More about nares here https://forum.arctic-sea-ice.net/index.php/topic,176.msg196830.html#msg196830

48
Arctic sea ice / Re: The 2019 melting season
« on: April 26, 2019, 12:14:48 AM »
what interest me is your take on the game heat+wave-action against replenishing wind-driven
new ice flushed out into the barentz ?

I'm not sure yet. Maybe, as you say, big drops. Or expansion on the Atlantic side dampens drops on the Pacific side. Of course, the expansion on the Atlantic side isn't good for the ice in the longer term, because it melts out at those lower latitudes (but maybe not right away, because it's end of April).

If this weather or similar keeps up, it should be possible for 2019 to stay close to 2016 during May. Here's the JAXA SIE graph for May:

49
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: April 23, 2019, 11:41:36 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

Will 2019 stay as the lowest on record for the whole April?
Or will 2016 become the lowest on record on the following days?

If the GFS/Euro forecasts hold for the next 8 days, that extreme heat event is going to kill almost all Okhotsk and Bering sea ice. That's 400,000 km2 by itself, which would have us atleast 100k lower than 2016.

I say 2019 holds easy to the end of April. Worse case, we add to the lead over 2016.

50
Arctic sea ice / Re: The 2019 melting season
« on: April 23, 2019, 03:10:28 AM »
Blocking highs are not something new, but their intensity and persistence in increasing. The record Greenland melt years of 2010 and 2012 were associated with strong high pressure over Greenland. Those were also bad years for the Arctic sea ice.

The coming together over the Arctic ocean of the Alaskan block and the Greenland block is particularly bad for sea ice because it creates a dipole that imports heat from the Pacific and exports ice through the Fram Strait.

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