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bairgon

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1150 on: June 21, 2017, 08:50:36 AM »
Is this mud?  Is it from a stream or melting permafrost or what?
Second image zoomed out for reference

Looks like silty river flow to me - and appears to be the Amguema. See https://en.wikipedia.org/wiki/Amguema_River. Very similar to the Mackenzie delta, though on a smaller scale. See the gif below.

The Mackenzie delta melt has been impressive since then. See animation from 1st June below.

Shared Humanity

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1151 on: June 21, 2017, 01:07:37 PM »
Certainly looks like silt.

gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1152 on: June 21, 2017, 06:57:24 PM »
Anybody any ideas on what to do when NSIDC's record of arctic sea ice stops ?
This now seems inevitable sooner rather than later now we know the last remaining satellite on earth has been sent to the junkyard by Congress and no 18 up there is already operating beyond its design life.
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epiphyte

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1153 on: June 21, 2017, 07:29:41 PM »
When I look at Nullschool's depiction of the developing CAB cyclone, there's a large volume of precipitation in the forecast. In the areas where it is predicted the surface temp shows up as somewhere between -0.3 and +0.5 degrees. However, there's also a "1000 MB temp" graphic available - and for this system, at least, it consistently shows a core temp for the cyclone several degrees higher than the surface temp.

I've been interpreting the above as implying that the precip will mostly be falling as rain onto wet ice/snow... (and from what little I can tell of the actual effect on the surface this seems quite plausible)

But it just now occurred to me that the forecast SLP in the eye of the cyclone is only 970MB! So my stupid question of the day is...

 - What does the 1000MB temp mean when the SLP is less than 1000MB?

FredBear

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1154 on: June 21, 2017, 08:06:28 PM »
One thing that puzzles me each year is the colour of the ice in the Foxe Basin - it is always a more creamy white than the rest of the sea ice (due to algae/diatoms?) yet drifts about and melts out later than I expect. Any reasons known?

TerryM

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1155 on: June 21, 2017, 08:45:45 PM »
One thing that puzzles me each year is the colour of the ice in the Foxe Basin - it is always a more creamy white than the rest of the sea ice (due to algae/diatoms?) yet drifts about and melts out later than I expect. Any reasons known?


I've always suspected ongoing CH4 emissions under Foxe Basin, the Inuit referred to it as having "brown ice" IIRC. The large, recently created, (after permanent ice), pingo like structures under Hudson Bay indicate CH4 blowouts there & Foxe is close by, but further North.
No data that I know of - just a hunch.


Terry

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1156 on: June 21, 2017, 08:47:03 PM »
One thing that puzzles me each year is the colour of the ice in the Foxe Basin - it is always a more creamy white than the rest of the sea ice (due to algae/diatoms?) yet drifts about and melts out later than I expect. Any reasons known?
Yes that's a puzzler. My understanding it gets some of its ice from the north, but this isn't nearly enough to explain the constant whiteness (seemingly) of the basin. There could be a sonewhat closed circulation within it but still it looks odd. It's one of the few areas keeping the cold better than normal if you ask me. Why tthat would be, it's odd. Not of course very significant wrt whole arctic but still an odd place weatherwise up there. Maybe the somewhat brackish waters of Hudson play an influence?

JimboOmega

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1157 on: June 21, 2017, 09:14:35 PM »
People in the main thread are talking about cyclones dragging cold air into the arctic.

Where does that air come from? The arctic is the coldest part of the northern hemisphere already... right?

Tigertown

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1158 on: June 21, 2017, 09:15:19 PM »
When I look at Nullschool's depiction of the developing CAB cyclone, there's a large volume of precipitation in the forecast. In the areas where it is predicted the surface temp shows up as somewhere between -0.3 and +0.5 degrees. However, there's also a "1000 MB temp" graphic available - and for this system, at least, it consistently shows a core temp for the cyclone several degrees higher than the surface temp.

I've been interpreting the above as implying that the precip will mostly be falling as rain onto wet ice/snow... (and from what little I can tell of the actual effect on the surface this seems quite plausible)

But it just now occurred to me that the forecast SLP in the eye of the cyclone is only 970MB! So my stupid question of the day is...

 - What does the 1000MB temp mean when the SLP is less than 1000MB?
That is a really good question. A 3-D model of such a cyclone would probably help, if someone knows where to find it. Other than that, maybe they are referring to the altitude that 1000 mb would normally be found without a cyclone, that is around 111 meters, though rounded off on their about page. Speaking of, Earth NS has this page https://earth.nullschool.net/about.html which seems to indicate that they are simply using the term as an altitude, but there is an email address on the page for inquiries also.
"....and the appointed time came for God to bring to ruin those ruining the earth." Revelation 11:18.

JimboOmega

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1159 on: June 22, 2017, 12:18:54 AM »
When I look at Nullschool's depiction of the developing CAB cyclone, there's a large volume of precipitation in the forecast. In the areas where it is predicted the surface temp shows up as somewhere between -0.3 and +0.5 degrees. However, there's also a "1000 MB temp" graphic available - and for this system, at least, it consistently shows a core temp for the cyclone several degrees higher than the surface temp.

I've been interpreting the above as implying that the precip will mostly be falling as rain onto wet ice/snow... (and from what little I can tell of the actual effect on the surface this seems quite plausible)

But it just now occurred to me that the forecast SLP in the eye of the cyclone is only 970MB! So my stupid question of the day is...

 - What does the 1000MB temp mean when the SLP is less than 1000MB?
That is a really good question. A 3-D model of such a cyclone would probably help, if someone knows where to find it. Other than that, maybe they are referring to the altitude that 1000 mb would normally be found without a cyclone, that is around 111 meters, though rounded off on their about page. Speaking of, Earth NS has this page https://earth.nullschool.net/about.html which seems to indicate that they are simply using the term as an altitude, but there is an email address on the page for inquiries also.

I think they are probably referring to the altitude at which 1000mb would be found, assuming the atmosphere extended that low (which it does not, in this case). So if the cyclone was over the dead sea, then 1000mb might indeed occur at some point in the atmosphere (even for a cyclone with a 970mb pressure at sea level), and they would expect it to have such a temperature.

georged

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1160 on: June 22, 2017, 08:40:00 AM »
People in the main thread are talking about cyclones dragging cold air into the arctic.

Where does that air come from? The arctic is the coldest part of the northern hemisphere already... right?

Generally the air above Greenland is colder than the arctic at this time of year, as I understand it.

Unmex Chingon

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1161 on: June 22, 2017, 03:17:46 PM »
Stupid question thread:  Are cars the biggest co2 problem?  And is the best solution = electric cars like the tesla?

Pmt111500

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1162 on: June 22, 2017, 03:30:27 PM »
Straight away a partial answer would be that the best solution would be walkable/bicyclable commutes and shopping trips. As the produce still needs to move then some electric van + electrified train is hard to beat. Then use Linux on difficult mode to do communication with people... But K' electric cars could be part of the system...

The most difficult human system to convert to solely use renewable energy would likely be farming/forestry, for the distances, but it cannot be the biggest problem i think as we need food and wood for construction...

DoomInTheUK

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1163 on: June 22, 2017, 03:33:28 PM »
Stupid question thread:  Are cars the biggest co2 problem?  And is the best solution = electric cars like the tesla?

Cars a large problem, but not the biggest. Electrical generation takes that spot.

https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions

Pmt111500

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1164 on: June 22, 2017, 06:19:31 PM »
Stupid question thread:  Are cars the biggest co2 problem?  And is the best solution = electric cars like the tesla?

Cars a large problem, but not the biggest. Electrical generation takes that spot.

https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
Yep, and that's an issue that is quite large, though the link is for US numbers. Situation is a bit different elsewhere, but the situation in US underlines the issue pretty neatly.

RoxTheGeologist

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1165 on: June 22, 2017, 09:38:28 PM »

California Fuel transport and production of fuel produces almost 50% of the GHG (the refineries consume a lot of energy to make the fuel) something like 50% of the industrial source is from them. See below:

https://www.arb.ca.gov/cc/inventory/data/data.htm

Power is only 19%

Power is rapidly becoming renewable, extensive solar arrays are being built. There are a number of big sources, and if you produce more than 25000 ton per year you are obliged to offset in the cap and trade carbon auctions. Basically anybody with a decent sized burner.

Kate

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1166 on: June 23, 2017, 02:21:46 AM »
So I updated my browser and now I can't find the page with all the data about the Arctic...had the graphs, anomalies, greenland melt etc...can't for the life of me find it again...would appreciate help :)

slow wing

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1167 on: June 23, 2017, 03:07:13 AM »
Kate, was it ASI graphs?

It's actually linked at the top of this page, immediately below the graphic, but the link isn't underlined so it isn't obvious.

wili

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1168 on: June 23, 2017, 03:47:02 AM »
Doom, your data is from 2015. I believe since then transportation has surpassed electric production for contributions to GW. Others can find the links to support if they wish. Too tired to do so now myself. But maybe I'm mis-remembering?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Kate

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1169 on: June 23, 2017, 07:30:45 AM »
Kate, was it ASI graphs?

It's actually linked at the top of this page, immediately below the graphic, but the link isn't underlined so it isn't obvious.

 :-[ yep....thank you

DoomInTheUK

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1170 on: June 23, 2017, 09:09:46 AM »
Doom, your data is from 2015. I believe since then transportation has surpassed electric production for contributions to GW. Others can find the links to support if they wish. Too tired to do so now myself. But maybe I'm mis-remembering?

Wili - you might be thinking of a regional or national case. But Electricity generation has been growing worldwide far quicker than transport build up. Think of India and China.

Here's a handy site that lets you track the data by various regions.
http://www.tsp-data-portal.org/Breakdown-of-GHG-Emissions-by-Sector-and-Gas#tspQvChart

wili

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1171 on: June 23, 2017, 09:09:28 PM »
DITUK, yeah, it might have been US data. But we in the US think we are the world anyways, right??  ;D ::) 8) :o
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1172 on: June 25, 2017, 03:19:09 PM »
GREENLAND MELTING : NSIDC and DMI
I look at two sites on Greenland melting:-
http://nsidc.org/greenland-today/,
and
http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/

The two graphs of melting were similar in May, but now show entirely different assessments. I have read the notes on what the data is and how it is collected and analysed, and cannot see any reason for such a profound difference to emerge.
I have recently been relying on the Denmark Meteorological Institute site as there is a lot more insight on it. But is this wise? Anybody any idea on what is going on? Je suis confus, embrouillé, désorienté.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1173 on: July 03, 2017, 05:24:31 PM »
Is there an easy way to move a posting from the the thread on which it does not belong to the thread to which it does belong ?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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Tigertown

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1174 on: July 03, 2017, 06:38:53 PM »
Open a second window(depending on what you are using, of course) and go to the thread you want the comment to appear, and enter the reply button. Go back to the thread that the comment is currently in and hit the quote button but don't post it yet. Copy and paste the whole thing to the new thread in the new window and post it. Go back and delete the new(quoted) and old posts in the thread that you don't want it to be in.

There may be an easier way, but that works for me.
"....and the appointed time came for God to bring to ruin those ruining the earth." Revelation 11:18.

Tor Bejnar

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1175 on: July 05, 2017, 03:29:48 PM »
This must be a stupid question, as it received no response  :o
...
Are there delta maps showing how much ice melted (or moved away) between the end-of-April (or May) time period and area, extent or volume minimum?
Areas that melt out go from X meters to zero (where X is usually 2 m or less), most CAB ice (for example) goes from X meters to Y meters.  Greenland Sea ice goes from X to Y, but the relationship between X and Y has little to do with melting. 

There are maps showing MYI that have to track each bit over several years as winds and currents move them about, and A-Team put an interesting movie showing where some ice 'features' were last autumn and where they are today (and tracked their movements). 

A first approximation of my desired map would simply show a subtraction of mid or late September thickness from "May" (one from mid-April and one from May 30?) thickness.

Ultimately, I'd like to see maps (from different years) showing how thick ice is at minimum compared with its 'recent' thickest (typically April [for southern ice] to late May [for CAB ice]).  Three layers of the map would show
  • current ice extent and thickness,
  • how thick this ice was at maximum (April to June, depending on where this ice was at the time) (possibly just a background layer) and
  • how much melted (or sublimated or got eaten by polar bears or just spread out - this layer would extend over ice-free areas).
[Alas, I do not have the technology to do any of this.]
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1176 on: July 05, 2017, 04:11:49 PM »
Tor, I believe this question is OT. It belongs in the Smart Questions thread instead.
I would put it in simpler terms though - what is the typical thickness lost during the melting season, depending on the location of the ice (as it moves).

Tor Bejnar

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1177 on: July 05, 2017, 04:24:08 PM »
Tor, I believe this question is OT...
I guess I just can't win ::)

Yes, a simpler response would be to have a map outlining the several Arctic regions with a single thickness number (in meters) in each that represents the typical thickness loss for that region, perhaps with a map for each year (or decade).  These maps might be overlain on minimum (or average minimum) extent map.
« Last Edit: July 05, 2017, 04:31:50 PM by Tor Bejnar »
Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

RealityCheck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1178 on: July 15, 2017, 10:11:13 AM »
Re various posts about CO2 emissions: in some EU countries Renewable electricity is getting high penetration e.g. Ireland, Germany, Denmark, UK (still EU for now 😉). France dominated by nuclear i.e. Low CO2 intensity. The EU targets for emissions reduction are most likely to be met in power sector.

Transport is more problematic but progress is being made, e.g. EVs, HEVs, PHEVs, fuel cells, electric trains (and of course all EVs then rely on the power sector). HGVs will likely need biogas, fuel cells or some combination to reduce emissions.

But it is space heating where the biggest challenges lie, e.g. In Ireland where targets are being missed. Energy system modelling for least-cost solutions to 2050 and with CO2 emissions constrained to zero show electrification of as many systems as possible, e.g. Incl heat pumps for heating and cooling, are the way to go.

All of which fails to address agriculture, especially meat production. So in Ireland, we could in theory meet all our Energy needs from domestic Renewable energy sources and get to zero emissions. But we'd have to shoot every cow in the country and say bye-bye to our meat and dairy industries. Hobson's choice..
Sic transit gloria mundi

Shared Humanity

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1179 on: July 15, 2017, 04:52:11 PM »
Re various posts about CO2 emissions: in some EU countries Renewable electricity is getting high penetration e.g. Ireland, Germany, Denmark, UK (still EU for now 😉). France dominated by nuclear i.e. Low CO2 intensity. The EU targets for emissions reduction are most likely to be met in power sector.

Transport is more problematic but progress is being made, e.g. EVs, HEVs, PHEVs, fuel cells, electric trains (and of course all EVs then rely on the power sector). HGVs will likely need biogas, fuel cells or some combination to reduce emissions.

But it is space heating where the biggest challenges lie, e.g. In Ireland where targets are being missed. Energy system modelling for least-cost solutions to 2050 and with CO2 emissions constrained to zero show electrification of as many systems as possible, e.g. Incl heat pumps for heating and cooling, are the way to go.

All of which fails to address agriculture, especially meat production. So in Ireland, we could in theory meet all our Energy needs from domestic Renewable energy sources and get to zero emissions. But we'd have to shoot every cow in the country and say bye-bye to our meat and dairy industries. Hobson's choice..

Where's the question? Just a reality check.  ;)

RealityCheck

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1180 on: July 17, 2017, 12:14:41 AM »

Where's the question? Just a reality check.  ;)

Upstream in the thread... 'Re CO2 emissions'... only my post dates from before I figured out how to quote from previous posts! (And assuming this thread can also be used for answers to the questions posted, of course!)

Anyhoo, thanks for the name check 👍

And to keep it 'honest', here's a brand new question as a follow up to my previous post:  will seaweed diet supplements save the Irish cows? (Cf today's Irish Times) 😉
Sic transit gloria mundi

DavidR

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1181 on: July 17, 2017, 10:25:20 AM »
And to keep it 'honest', here's a brand new question as a follow up to my previous post:  will seaweed diet supplements save the Irish cows? (Cf today's Irish Times) 😉

According to  Australian research a small amount  of seaweed removes 99% of the methane.
http://www.abc.net.au/news/2016-10-19/environmental-concerns-cows-eating-seaweed/7946630

However I think the purpose of this thread is for questions about Sea Ice not random queries.
Toto, I've a feeling we're not in Kansas anymore

Neven

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1182 on: July 18, 2017, 02:46:32 PM »
From the Melting Season thread:

Given that <15% SIE represents an Ice Free Arctic, can anyone tell me what the actual figure would relate to 15% and how much was year 2012 greater than this figure.
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oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1183 on: July 18, 2017, 03:07:53 PM »
From the Melting Season thread:

Given that <15% SIE represents an Ice Free Arctic, can anyone tell me what the actual figure would relate to 15% and how much was year 2012 greater than this figure.
Jontenoy, The 15% criterion is used to determine whether a given grid cell has ice extent or not. It is not used on an arctic-wide basis. So for the NSIDC grid, take a 25x25km box, 625 km2 total, if ice area in that box is less than 93.75 km2 then that specific box is counted as "ice free".
The usual definition of "ice free arctic" is "less than 1 million km2 of ice extent". 2012 came in at 3.18 million km2 for the daily record low, still way above the criterion.
« Last Edit: July 18, 2017, 03:59:10 PM by oren »

Peter Ellis

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1184 on: July 18, 2017, 04:34:37 PM »
Mind you, by an ironic conincidence, "less than 1 million km2 of ice extent"  is almost exactly 15% of the average 1990s summer minimum...

magnamentis

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1185 on: July 18, 2017, 06:07:16 PM »
Mind you, by an ironic conincidence, "less than 1 million km2 of ice extent"  is almost exactly 15% of the average 1990s summer minimum...

nice find and in addition to that, i said that before, once we indeed will have reached sub-one-million km2 nobody will talk about ice-free arctic anymore because there will simply be too much clearly visible ice left to use that term at that time. it will sound non-credible and alarmist would the media talk about ice-free while everyone could see lot's of ice on sat-images.

this currently widely spread interpretation has IMO been made up by people who cannot wait till it happens and hence bended the rules/terms to their liking.

1 mio km2 is definitely NOT ice-free, no matter what anyone tries to tell us.

EDIT: the term alarmist as well has a negative touch which is not justified, i believe that nothing is wrong to be alarmed and the alarms should even be much louder and wider spread. we need more alarms not less.

Neven

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1186 on: July 18, 2017, 07:09:19 PM »
Mind you, by an ironic conincidence, "less than 1 million km2 of ice extent"  is almost exactly 15% of the average 1990s summer minimum...

Ha, I was wondering about that. Thanks, Peter.

this currently widely spread interpretation has IMO been made up by people who cannot wait till it happens and hence bended the rules/terms to their liking.

1 mio km2 is definitely NOT ice-free, no matter what anyone tries to tell us.

I like to say 'ice-free for all practical purposes', after hearing Walt Meier putting it like that once.
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magnamentis

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1187 on: July 18, 2017, 08:33:25 PM »
@neven

:)

Flocke

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1188 on: July 22, 2017, 10:02:33 PM »
I'm looking for sources about earth's outgoing radiation spectrum, especially its change over time, presumably measured by satellite.
Considering its importance for greenhouse effect and AGW, there should be something on this forum, but I'm unable to find it.

ktonine

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1189 on: July 23, 2017, 05:53:48 AM »
I'm looking for sources about earth's outgoing radiation spectrum, especially its change over time, presumably measured by satellite.
Considering its importance for greenhouse effect and AGW, there should be something on this forum, but I'm unable to find it.

Total Solar Irradiance (TSI) is measured by several different groups.  As you can see from this SORCE historical reconstruction graph it varies by and average of < 0.7% minima to maxima over a solar cycle.



Home Page of the SOlar Radiation and Climate Experiment (SORCE)

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1190 on: July 23, 2017, 07:22:28 AM »
Ktonine, I believe the question was about Top of Atmosphere outgoing "black body" radiation

sidd

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1191 on: July 23, 2017, 07:50:38 AM »
for top of atmosphere fluxes

https://ceres.larc.nasa.gov/products.php?product=EBAF-TOA

note this caveat: "The CERES absolute instrument calibration currently does not have zero net balance and must be adjusted to balance the Earth's energy budget."

from one of the steps in the processing, noted at:

https://ceres.larc.nasa.gov/science_information.php?page=EBAFbalance#Eanalysis

In practice they constrain to ocean heat content increase as outlined in a 2005 Hansen paper.

they also have surface fluxes

sidd
« Last Edit: July 23, 2017, 08:02:30 AM by sidd »

Cid_Yama

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1192 on: July 23, 2017, 06:10:40 PM »
The net positive imbalance is small, 2% for SW and 1% LW.   
"For my part, whatever anguish of spirit it may cost, I am willing to know the whole truth; to know the worst and provide for it." - Patrick Henry

Laurent

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1193 on: July 25, 2017, 09:20:28 AM »
Does someone know why there is such a huge difference between the NOAA value of CO2e (489 ppm) (I know "reality" is near 520 or more if we calculate on 10 years basis) and the RCP8.5 scenario which is at ~412 ppm (https://en.wikipedia.org/wiki/Representative_Concentration_Pathways#/media/File:All_forcing_agents_CO2_equivalent_concentration.png) ?
« Last Edit: July 25, 2017, 12:16:56 PM by Laurent »

Ned W

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1194 on: July 25, 2017, 02:53:16 PM »
Mind you, by an ironic conincidence, "less than 1 million km2 of ice extent"  is almost exactly 15% of the average 1990s summer minimum...

Ha, I was wondering about that. Thanks, Peter. [...]

I like to say 'ice-free for all practical purposes', after hearing Walt Meier putting it like that once.

Someone has almost certainly already done this, but I don't know where, so I re-invented this wheel...

Here's a map showing what 1.0 million, 0.5 million, and 0.1 million km2 of ice extent could look like.  It's based on the grid cells with the maximum concentration in NSIDC September maps for the years 2008-2016.  My assumption is that ice will last longest in grid cells where Sept concentration is consistently the highest over the past decade.



If someone knows of a better version of this analysis here or elsewhere, please let me know!

Looking at the map, I'd say that 1 million km2 is actually a bit high for an "ice-free" threshold, personally.   

Peter Ellis

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1195 on: July 25, 2017, 03:16:08 PM »
... whereas it's also clear that even with 2 million km^2 you could end up in a situation with essentially unimpeded navigation from Svalbard straight over to the Bering strait. For shipping purposes, the Arctic Ocean will be effectively ice free long before we reach 1 million km^2.

greatdying2

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1196 on: July 25, 2017, 03:40:17 PM »
I have the feeling that by the time we get to such a small amount of remaining ice it may not stay nicely in one sector, and thus perhaps such questions may become moot.
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

oren

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1197 on: July 25, 2017, 06:53:09 PM »
Great map Ned. Reaching 1 million will not be easy. The actual melting season around the pole is just 3.5 months (~June 1st to Sep 15th). Ice mobility, waves, cyclones, season lengthening, all contribute to more melt. But it could take a decade to get there.
In terms of effects on climate, 1 million is much closer to ice free than to the previous ice/climate regime, so I think it's a good proxy.

gerontocrat

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1198 on: July 25, 2017, 08:01:28 PM »
Volume is reducing at a significantly higher rate than extent. One year extent must collapse. But when !!??**
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Ned W

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Re: "Smart" and "Stupid" Questions - Feel Free To Ask
« Reply #1199 on: July 25, 2017, 09:00:33 PM »
Volume is reducing at a significantly higher rate than extent. One year extent must collapse. But when !!??**
Yes, they have to reach zero at the same time, but there is more than one way that could happen:

* Extent could speed up to match volume
* Volume could slow down to match extent
* They could meet in the middle