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Messages - RoxTheGeologist

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101
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 09:24:53 PM »
@jdallen, Yeah definitely. Bottom melt gradually ramping-up , all that mess over Beaufort ESS and even Laptev has time to melt out. August + 3 weeks ahead, and bottom melt doesn’t stop until end of october for the warmest ocean areas.
BTW water warmed by radiation can mix with water beneath the ice. A slow process enhanced with movement. Why people think now it’s like oil on water? In the Beaufort certainly the salinity differences are relatively small.
And even part of Chukchi water can mix while in the shelf before sinking. We see those fingers that the currents form causing eddies engulfing half the warm water and half the pack. After mixing, which takes time in those structures , density stratification is less prone to happen and water temperature beneath the ice must increase.
I don’t believe that the fast edge retreats we observe in late years is not directly enhanced by warm currents from Pacific.

It's been well observed that the ice edge tracks bathymetry. The Barents continental slope often delimits the edge of the sea ice between the Barents Sea and the Arctic. This season the ice  pretty much tracks the continental slope of the Canadian Basin, except in the most southerly regions, the Beaufort. The reason is that the typically saline ocean waters cool and sink as they meet the ice edge, and that water can only sink when it reaches the continental slope.

Water temperature beneath the ice in the basins does increase at depth, but it doesn't mix with surface waters. Ice melts from the edges for a good reason. If the central pack is to melt, it isn't going to be from mixing with warm water from adjacent seas unless the ice gets spread out and deeper waters are mixed by a GAC. The Atlantic water under the Nansen basin already contains enough heat to melt all the ice. The pack will melt because it's thin and from the weather, insolation and air that is extra warm and wet because the peripheral seas have little ice.

Ice melts from the bottom, because the salinity means that it can melt at lower temperatures. if the surface of the ice is at 0°C and the base -1.8°C, any heat input into the system will melt the base at equilibrium, and not the surface. It's a balance between the conductivity of the ice, it's thickness, and how much energy is being put into the surface.

102
Arctic sea ice / Re: The 2019 melting season
« on: July 26, 2019, 05:52:01 PM »
Likely that both are.
Well i wouldn't say "likely" (also, no scorning, remember? :) ) , - but "possible" both are, yes. Which is why i used "at least" in the post you quoted, you see.

But which way? I mean, if you say it's not 2m+ CAB average and not ~1.2...1.4m CAB average, then what is your idea? Somewhere in-between, or <1m? Intresting!
Thin in some places, fat in others.

For a second I thought you were describing me.

103
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 25, 2019, 06:14:14 PM »

NSIDC - daily numbers place 2019 at 29/40 years

104
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 25, 2019, 09:09:36 AM »
In the meantime, this graph is up-to-date

That's a big gap considering the insolation the ice and water is about to absorb.

105
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 09:08:13 AM »
...
Completely different issue than SST. I saw that Rox referred to SST and thought she made a mistake which I did not correct.
...

Completely OT, but I'm surprisingly happy you determined my gender. It's almost as accurate as your analysis. Perhaps Rox = Rocks?

106
Arctic sea ice / Re: The 2019 melting season
« on: July 25, 2019, 01:51:03 AM »
The dipole has arrived. But it does not come with a lot of heat.

The SST's are very warm around the edges, but in no rush to invade the CAB.

2019 leads in some categories, but area losses are skipping, suggesting lost momentum.

The wind remains impressive, but mostly cold and pointed away from Fram. Some compaction, some dispersion, some export. Nothing record breaking.

The ice is in crap condition, but it won't disappear w/o good reason. Especially from the CAB.
 
I'm rooting for a record and anything else that might occur in the short term that will jolt the world ioward the necessary urgent response to AGW.

Second place doesn't make headlines. That where it looks like we're headed.

SSTs in the ice pack are buffered at 0°C or thereabouts by melting ice. You don't see the SST increase until all the ice is melted. You can't tell how much ice is melting by looking at SSTs until all the ice is gone.

107
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 24, 2019, 06:54:07 PM »
Here's a more informative way to look at the central Arctic - a sea surface height map. There are strong SSH gradients across the central Arctic indicating strong flow of water and ice. This year the transpolar drift has been strong and has run right through the central Arctic. The areas in the central Arctic basin with high SSH store fresh water and the areas with low SSH are dominated by cold salty water.

FOW - When you say store, wouldn't the density difference in the water column mean that the freshwater flows from high to low areas? I assume (probably incorrectly) that the elevated SSH topography is dynamic, that the pool of freshwater is continually replenished (say, though river input) and mixes and disperses unless there is some external force (such as the BG) that creates a physical force to maintain the hydrostatic imbalance.


108
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 24, 2019, 06:45:12 PM »

For NSIDC the current extent would place 2019 as 33/40 years at the minimum, with roughly 7 weeks still to go in the melt season.

109
Arctic sea ice / Re: The 2019 melting season
« on: July 23, 2019, 06:00:51 PM »
This looks like the Great Arctic Anticyclone with strong winds and waves and clear skies. The sun still be high in the sky. I expect singnificant ice drop in any metrics.

High in the sky ? Under the anticyclone centre area (at 85N) the sun elevation angle will vary between 15 and 25 degrees.

Ok I know the sun does not set but from elevation angle POV, this is something similar to a January 10th afternoon in Boston, Mass.

the insolation is about the same as 30°N  right now. Are you saying that sea ice wouldn't melt under the Floridian Sun?

The only thing saving the ice from soaking up all those Watts is that it's still pretty white over a lot of the CAB, perhaps reflecting 60%. With that amount of sunshine it will darken quickly and as the ice thins the water under the ice absorbs more and more energy. The open ocean is going to soak up 90%.




110
Arctic sea ice / Re: The 2019 melting season
« on: July 22, 2019, 09:43:09 PM »
The thing I find remarkable about the upcoming weather (climate reanalyzer) is that there is some snow forecast, but it is going to be over the largely open water on the Siberian side of the Arctic. Precipitation over the central basin is low or predicted to be rain. I think that is the other reason why cyclones slow down melt, other than clouds; fresh, high albedo snow. !0 day cumulative precipitation below:

111
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 22, 2019, 06:57:08 PM »
I am not the big sea ice interpreter, but I find it interesting that Foxe Basin is ahead of Hudson Bay when it comes to melting of sea ice? That it very unusual I think?

I remember someone commenting very early in the season that the ice in Hudson Bay was much thicker than normal and would take a long time to melt out this year.

The Foxe basin was really hot early in the year. The snow on Baffin Island cleared very early. Lots of nice clear sky and high temperatures. From what I can tell (on worldview) the melt lakes to the east of the Barnes ice cap have melted out earlier than ever. I bet it's going to be a record loss of ice from that ice cap this year.

112
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 22, 2019, 06:50:31 PM »
The earths outgoing energy (Wm2) on average is 239, so when the incoming radiation drops below that, you'd expect temperatures to drop and eventually for ice to form.
https://en.wikipedia.org/wiki/Earth's_energy_budget
That is way to oversimplistic. The 239 Wm² of outgoing radiation is on average for the whole earth the whole year. But low latitude emit much more, than high latitudes on average, because it simply is warmer. When it is warmer, the outgoing radiation also increases, and vice versa. Then the 239 Wm² cover all from clouds to the surface. Then a lot of heat is transported through convection of air as well as through ocean currents and a lot of heat is buffered by the oceans, which will warm in summer and release that heat back in winter.

If ice would form anywhere simply because the average insolation on the ground would drop below 240 Watt/m², you would have a frozen Atlantic ocean down to 40° North, so the UK or New York woud see sea ice, which obviously isn't true.

Insolation in the Arctic even at the pole is till mid August still higher, than it is in winter e.g. in Los Angeles (33°N) or in North Carolina (35°N), where it is pretty warm even in winter.

Currently the insolation in the Arctic even at the pole is higher than on the Equator. So IMO a week of high pressure with a lot of sun will not be a good thing for the ice and I suppose that it would lead to massive melt in many areas. Additionaly, depending on the location of the high pressure system, that could also lead to a lot of ice being exported through Fram strait or just pushed out around Franz Josef Land into warmer Atlantic waters where it would melt out.

IMO the worst thing that could happen would be, that we would see 2 weeks with a lot of sunshine and insolation (while we are still near the insolation peak), which would thin the ice a lot more, and then a heavy storm in the second half of August which would slash that remaining ice.


Here's the OLR for July, close to 225 - I did simplify to make the point that the incoming radiation is much higher than outgoing, so clear sky in July has a positive energy balance. It seems that the July OLR is pretty close to the earths average :).

http://cimss.ssec.wisc.edu/wxwise/homerbe.html



113
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 22, 2019, 12:18:20 AM »
It has been stated in the melting thread that there's a possibility of a huge high pressure ridge forming over the Arctic Ocean, and that if it happens it will be very bad for the ice.

But would a huge high pressure ridge be bad for ice retention, and why? Just because insolation is still high for a few more weeks? But wouldn't it also bring an end to the winds? Wouldn't big storms be worse?
BTW the same question you asked in the MST came to me the moment i was reading all the exited posts that, if it were mid june to mid july, were true, but people get used to keywords and key-events, often forgetting that the high season for a specific pattern is over or at least reduced and almost over.

Exactly.

I can't help but continuing to mull over the 2012 GAC, which exactly coincided with that year's 2D curves (extent, area) beginning to diverge from basically tied for lowest to way lower. I have read the objections about the GAC not being the main cause, but remain skeptical. It seems plausible to me that the worst thing for the ice this time of year (or at least in a couple weeks), now that the pack is fully mobile with plenty of warm water and air nearby, would be storms*. Yes, this is simplistic thinking and I'm no meteorologist, but on the other hand the "high pressure is bad" trope is no more sophisticated. Which is why I asked.

* Given a sufficient setup, which we seem to have this year as in 2012.



The earths outgoing energy (Wm2) on average is 239, so when the incoming radiation drops below that, you'd expect temperatures to drop and eventually for ice to form.
https://en.wikipedia.org/wiki/Earth's_energy_budget

It looks like the north pole drops below that sometime in late august. If you have less reflection from clouds in July it means that the ice and oceans are absorbing extra energy through insolation then they are losing. More energy = more ice melted.

In late July the energy absorbed is still as high as 60°N and almost as high as 30°N. That's pretty nice and toasty.

114
Arctic sea ice / Re: The 2019 melting season
« on: July 18, 2019, 07:53:14 PM »
The Coriolis effect tends to make the water flowing into the Arctic, from both the Atlantic and Bering strait, turn right. The warm water in the Bering strait goes into the Alaskan Coastal Current that flows eastwards on the north slope and may also go into eddies on the Chukchi shelf. In the fall the water may sink below fresher surface water forming the "summer water layer". This melting season heat stored from last year may be melting ice that has pushed from the CAA into the Beaufort sea.

You can see the mixing up of the summer water layer heat in recent buoy profiles from the Beaufort sea. That heat is helping to melt the thick multi-year ice imported from the CAA.

The extraordinarily warm water that we see now along the Alaskan coast will not directly affect the ice in the central Arctic but the heat will have indirect effects this year and next year. The continuing build up of heat in the Beaufort sea is leading to "Pacification" of the Alaskan side of the Arctic ocean and is playing a major role in multi-year sea ice decline.

http://psc.apl.washington.edu/HLD/Bstrait/BeringStraitSeasonalInterannualChange2017.html

Abstract 

Year-round in situ Bering Strait mooring data (1990-2015) document a long-term increase (~0.01Sv/yr whole record, ~0.02Sv since 2000) in the annual mean transport of Pacific waters into the Arctic.  Between 2002 and present (2015), all annual mean transports (except 2005 and 2012) are greater than the previously accepted climatology (~0.8Sv).  The record-length maximum (2014: 1.2�0.1Sv) is 70% higher record-length minimum (2001: 0.7�0.1Sv), corresponding to a ~1/4year reduction in the flushing time of the Chukchi Sea (to ~4.5months from ~7.5months).  The transport increase results from stronger northward flows (not fewer southward flow events); the velocity distribution's annual mode ranges from <25cm/s to >40cm/s, a 60% increase in speed and a 150% increase in kinetic energy, a metric which scales with the flow's impacts on bottom suspension, mixing and erosion. 


The Chuckchi sea's sea ice loss and resulting warmth may have profound effects, where the warm sea is warming the Beaufort gyres halocline, potentially slowing sea ice growth. We should worry if the Chukchi is above 13°C

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6114986/


The doubling of BG halocline heat content over the past three decades appears attributable to a warming of the source waters that ventilate the layer, where this warming is due to sea ice losses in the Chukchi Sea that leave the surface ocean more exposed to incoming solar radiation in summer. The effects of an efficient local ice-albedo feedback are thus not confined to the surface ocean/sea ice heat budget but, in addition, lead to increased heat accumulation in the ocean interior that has consequences far beyond the summer season. Strong stratification and weak mechanical mixing in the BG halocline ensure that significant summertime heat remains in the halocline through the winter.

With continued sea ice losses in the Chukchi Sea, additional heat may continue to be archived in the warm halocline. This underscores the far-reaching implications of changes to the dynamical ice-ocean system in the Chukchi Sea region. However, there is a limit to this: Once the source waters for the halocline become warm enough that their buoyancy is affected, ventilation can be shut off. Efficient summertime subduction relies on the lateral surface front in the NCS region between warm, salty water that is denser to the south and cooler, fresher water that is less dense to the north. For longer-duration solar warming (that is, longer-duration ice-free conditions in the region), SSTs on the south side of the front may become warm enough (around 13°C, under the assumption of a 1.5-month ice-free period dominated by solar absorption) that the lateral density gradient is eliminated [see (24)]. It remains to be seen how continued sea ice losses will fundamentally change the water column structure and dynamics of the Arctic halocline. In the coming years, however, excess BG halocline heat will give rise to enhanced upward heat fluxes year-round, creating compound effects on the system by slowing winter sea ice growth.


115
Science / Re: 2019 CO2 emissions
« on: July 17, 2019, 06:23:46 PM »

Also, there is a lot methane trap in coal deposits and released during coal mining.  That isn't taken into account in the above discussion.
There are installations in urban locations in the UK that are still collecting methane emitted from coalmines closed down 30 years ago. About the only places you can still see a sign"National Coal Board".

I guess in the USA and elsewhere the old coal mines just burp the stuff into the sky.

or they burn....

https://en.wikipedia.org/wiki/Centralia_mine_fire

116
Arctic sea ice / Re: The 2019 melting season
« on: July 16, 2019, 05:57:56 PM »
Unless you are looking at good detailed nautical charts you have no idea how deep specific small areas of a sea floor are. Shoals and banks as well as rock outcrops can be a few feet below the surface of an otherwise deeper area of ocean. I have not seen on-line anything on ocean depth that gets down to a scale that would detail such small navigational hazards for the arctic, though I suspect they exist if I were to search hard enough to find them.

I guess Google Earth Ocean floor doesn't exist yet? ::) I found this map that's very detailed, but maybe not detailed enough? On this map I am seeing a few little islands, so you're probably right that this could be an island that doesn't rise above the ocean surface. I'm posting the link, because the image is quite large in size.

https://nik.bot.nu/o3129683.jpg

I'm trying to reply to Rod, but I keep getting this message.
The following error or errors occurred while posting this message:
The message body was left empty.

So what am I doing wrong?

I'll post my reply to Rod here...

Thanks Rod. And no, I've already made Neven mad this weekend when I was posting while drunk, so I'm gonna try not to repeat that.  ;) I need an app that blocks me from posting while drunk...  :-[  :-X Sorry about that post Neven!

Water is opaque to radio waves, the only way to accurately map the oceans is with sonar, and there hasn't been much of that in the Arctic. That's why other planets are better mapped than the earth.

117
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 15, 2019, 05:46:12 PM »
Depth matters for when methane is released. The greater the depth, the less CH4 reaches the surface, especially if release is slow in little bubbles.

Of course, with brisk seeps in relatively shallow waters, we can expect the whole water column to become saturated with dissolved methane, at which point the released methane does reach the surface.

And each molecule of dissolved methane will, by biological processes, consume two molecules of oxygen.  Oxygen is a scarce commodity in the oceans.  Methane release anywhere in the oceans can exacerbate ocean hypoxia.  What happens when the cold, oxygenated waters that leave the arctic at depth (to replenish oxygen in the whole Atlantic ocean) cease being oxygenated?

Look at the black sea stratification and euxinic bottom waters.

Ocean anoixia is thought to have been responsible for mass extinctions in the oceans in the Paleozic and Meoszoic such as the early Toarcian


https://www.sciencedirect.com/science/article/pii/S0031018211005694

Its a very good reason NOT to do oceanic iron fertilization. For it to work the carbon either has to be dissolved into the ocean (promoting acidification) or it has to fall to the sea floor, and the latter only happens if you run out ox oxygen; causing mass death of sea creatures.



119
I think this illustrates the wide gulf between what is required to limit emissions and what is actually likely to happen:

North America Midstream Infrastructure through 2035 (June 2018)

https://www.ingaa.org/File.aspx?id=34658

"Natural gas exports are on the cusp of growing significantly, both to Mexico and as LNG to markets around the globe. Further, low gas prices have fostered growth in the power generation market as coal and nuclear plants continue to be retired across the U.S. This trend seems irreversible considering regulations that encourage clean power and the way in which gas complements renewables. Regardless of policies, the relatively low gas price environment generally discourages additional investment to upgrade or further limit emissions from coal plants, especially considering the threat of federal carbon control that still looms on the horizon.
The scenarios in this study project significant growth in oil and gas production and markets that stimulate such growth. U.S. and Canadian oil production increases to over 19 million barrels per day by 2035. Natural gas production growth is even more pronounced, increasing from roughly 91 billion cubic feet per day in 2017 to 130 billion cubic feet per day by 2035. NGL production will track gas production over time."

120

So I still argue that we're much more likely to limit the growth in temperatures to 2C or less than to see the 5 to 8C increase AbruptSLR is forecasting.


Well, we will have an answer soon, but the way that fossil fuel extraction has been increasing in 2019 coupled with the lack of clear government direction in the largest polluters.  Extraction is accelerating.

https://www.eia.gov/todayinenergy/detail.php?id=39332

I don't see any substantive change in emissions policy until 2021, and then you have had an extra trillion dollars or more of infrastructure built out. I would expect the ppm CO2 and fossil fuel usage to continue to INCREASE. We might see stronger policy start having an effect by 2025, as long as the democrats can stay in power. Gas and petroleum companies will NOT give up market dominance for power generation and transportation without incredibly strong policy. The market will simply no drive this. I know, I work in biofuels. Oil companies here are giving up $500m of credits so they don't have to blend biodiesel. They have lots of assets in the ground, and they will be making damn sure they get used to make the money out of them. There is enormous capped gas production capability in the US, the price will drop as pipelines are built out.

The best hope we have is for a severe global recession.

121

There is no such thing as a completely accurate model. Models are only as good as the tests they are subjected to.

We have observations that allow us to hindcast models to test them, to make sure they match the data that we have. That data is changing as our observations of the earth improve. Once we have a model that seems to be able to hindcast data then we can try to predict the future.

One problem with hindcasting is that it's easy to tweak the inputs to match the outcomes. However, if you make changes to the model that aren't back up by good theory, then it's basically data fitting the model. I haven't worked in climate modelling, but I would suspect that it's an easy trap to fall into as there are so many poorly defined parameters.

122

Coal is on the way out, as this report from three NGOs explains:


Unfortunately this isn't the case. 2018 was the forth highest year of coal production, and China restarted work on the 'cancelled' coal power plants. China is going to increase coal usage by 25%.

https://www.bbc.com/news/science-environment-45640706



And as the following scientific paper published in Nature this January indicates, the current fossil fuel infrastructure does not yet commit us to more than 1.5 C warming.


There is a boom of LNG infrastructure with 1.3 Trillion dollars in production.
http://www.xinhuanet.com/english/2019-07/02/c_138192647.htm


"Exceeding 1.5 °C occurs in only 9% of ensemble members under a zero emissions commitment if emissions cease at the end of 2018. Even if current fossil fuel infrastructure is retired at end of its lifetime and not replaced, it is possible to limit warming to 1.5 °C"

Neither of their scenarios relate to the real world, both from the increase in LNG and coal production and the record breaking production of shale oil in the US.


By Robert F. ServiceJul. 11, 2019 , 1:40 PM

Local commitments to switch to 100% renewables are also propelling the rush toward grid-scale batteries. By Jacobson's count, 54 countries and eight U.S. states have required a transition to 100% renewable electricity. In 2010, California passed a mandate that the state's utilities install electricity storage equivalent to 2% of their peak electricity demand by 2024.


Natural gas has being taking over a lot of the US capacity, its going to be a good long while before renewable energy replaces it. This is new infrastructure.

"EIA expects the share of U.S. total utility-scale electricity generation from natural gas-fired power plants will rise from 35% in 2018 to 38% in 2019 and then decline slightly in 2020. EIA forecasts that the share of U.S. generation from coal will average 24% in 2019 and 23% in 2020, down from 27% in 2018. The forecast nuclear share of U.S. generation falls from 20% in 2019 to 19% in 2020, reflecting the retirement of reactors at five nuclear plants in 2019 and 2020. Hydropower averages a 7% share of total U.S. generation in the forecast for 2019 and 2020, similar to 2018. Wind, solar, and other nonhydropower renewables together provided 10% of U.S. total utility-scale generation in 2018. EIA expects they will provide 11% in 2019 and 13% in 2020."

Global emissions will continue to grow as more infrastructure is built out. 2018 had the highest ever emissions from energy related sources, the easy fix for emissions targets. That doesn't include the increase in petroleum usage in transportation and the increased pace of devastation of rain forest.

from the IEA https://www.iea.org/geco/emissions/

"Global energy-related CO2 emissions grew 1.7% in 2018 to reach a historic high of 33.1 Gt CO2. It was the highest rate of growth since 2013, and 70% higher than the average increase since 2010. Last year's growth of 560 Mt was equivalent to the total emissions from international aviation"

and see

https://www.carbonbrief.org/unep-limiting-warming-to-1-5c-requires-fivefold-increase-in-climate-commitments

"Coal consumption grew by 1.4% in 2018, the fastest growth since 2013. This reverses a three-year period where coal either grew very little or actually declined, though global coal use still remains below its 2013 peak (see below for more)."

"Natural gas represented the single largest contributor to global energy-use growth in 2018, increasing by 5.3% compared to 2017. It alone was responsible for 40% of the increase in total energy use."

"Oil consumption grew by 1.5% in 2018, with China and the US contributing around 85% of the growth in oil use. This growth was primarily concentrated in the transportation sector, reflecting increased vehicle ownership and miles driven."

With the current governments in the US and Russia, Brazil. India isn't stopping production of coal plant infrastructure, 1.5°C is simply a pipe dream. We have to be cutting emissions, not increasing them, and renewable has simply no chance of keeping up the need for energy over the next decade, let alone starting to replace it.





123

And the discovery of an extra 0.1°C already in the oceans makes it even less likely

124
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 07, 2019, 07:56:11 PM »
Most of these melt ponds are partially covered by floating ice.  I've read that some melt ponds do not freeze solid during the winter (which surprised me), but it explains the phenomenon demonstrated here, floating ice on melt ponds on glacial ice.  As a melt pond gets deeper and wider with today's warm temperatures, the floating ice will sever its connection to the shore, and even if 'thick', won't reach the shore of the larger pond.  A possibility is for a melt pond to drain after the surface freezes in the winter, leaving a cave, so that when re-filled, the pond will lift the 'lid' as described just above.

Most of the melt ponds in that image have floating ice. Would suggest that melt ponds not freezing solid is a common occurrence. I remember being surprised by this as well.

A deep pool with the ice around the pool at 0°C. It can only lose energy from the top surface. Give that a nice cover of insulating snow. It does make sense when you think about it, but it is still really surprising. Also it would be terrifying to walk across an area of snow covered melt ponds!

125
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 05, 2019, 07:50:32 PM »
That's very interesting, Oren. I've looked at those videos before, but not specifically in order to see melt ponds draining. Perhaps most melt ponds do drain by floes breaking. On the other hand:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JC011994

Later in the melt season, pathways for water to pass between the ice surface and ocean become relatively unrestricted, first through the formation of large drainage holes, and later through the onset of permeability through the ice matrix [Polashenski et al., 2012]. After large levels of permeability are established, pond coverage is controlled by the fraction of the ice surface situated below sea level [Polashenski et al., 2012]. The timing of the transitions in pond evolution on first year ice is therefore heavily dependent on the particulars of ice permeability.

Maybe it's partly a question of semantics. One person's "large drainage hole" is another person's "floe breaking up"?

For the sake of argument....

If it's safe to assume that the ice is relatively homogeneous over an area (same freezing conditions, exposed to the same weather), and that the thermal state of the ice is therefore fairly consistent. then what happens to the warm water in a meltpond when it first drains?. The hydrostatic pressure should make the ice lift up as the melt water flows underneath the ice, presumably lowering the salinity of and warming the ice/water contact over a large area.  The ice also has to rise up by the average depth of the meltpond. The area where the melt water flows is controlled by the underwater topography of the ice. It's likely to flow along existing areas of thin ice (high spots). I'm assuming that it's less dense than the seawater below.

The surrounding melt ponds may drain because 1) the ice domes and the water in the ponds flows away 2) the warmer melt water flows along existing thin spots in the ice and provides the extra thermal push that causes any connected ponds to drain. 3) the flexure of the ice is taken up at weak spots by brittle failure, causing other weak spots to open and drain.

All three mechanism would seem to be capable of causing a cascade of melt ponds in an area to drain almost simultaneously.





126
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 05, 2019, 07:24:39 PM »
Clearly, the Japanese were celebrating the 4th of July.

Snark, aside days without reports are so common that conspiracy theories lack credence (without solid evidence).

I usually go for the cock-up theory over the conspiracy theory;. Entropy over organisation..

127
Arctic sea ice / Re: The 2019 melting season
« on: July 05, 2019, 07:16:46 PM »
Yes, that heat in Alaska will affect the ice because the southerly winds will blow over open water that's already absurdly warm for the Arctic before it reaches the ice. The warm air blowing off Alaska will still be pretty warm when it hits the ice because it is passing over water that's anomalously warm. The ice edge will be pushed back.

That's a great way to transfer heat from the warm water to the cold ice. Evaporation followed by condensation on the ice.

128
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 04, 2019, 06:45:48 PM »

...Lots of good stuff...


Thanks Ben, that all makes sense, I was thinking of a static flow with melt water draining into the ice and refreezing. I was trying to make sense of what we see from distance, white-blue-white-grey-black. The initial assumption that I made that the ice cant drain until the water below the ice is above freezing point of is probably not such a good starting point, A crack in the ice allowing a large pool to drain and overwhelm the ability of the colder ocean to freeze the melt.

It could also explain why wide swathes all seem to turn white at the same time. Would a flood of melt pool water form a cascading effect, warming the base of the ice of a large area, and helping all the adjacent ponds to drain, and rapidly spreading over a day or so? Or is the ice fairly homogeneous over a wide region, so maybe 10000km2 will all reach the conditions to drain simultaneously?


129
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 03, 2019, 11:08:14 PM »
Oh yeah, typo lol. I didn't double check :)

130
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 03, 2019, 10:48:34 PM »
Okay. Melt ponds. dumb questions?

I'm also very interested in the answers to these questions.

I would go for a 'yes' for 2) and 3).

The others are above my pay grade. I don't even understand 4).

question 4....

My idea is that it might go something like this:

We see blue melt ponds, and I think that implies that the ice and water below is still cold enough to freeze the base of the freshwater pond to stop it draining. Once all the ice heats up to 0°C, then the pond can drain due to density and we don't see blue anymore. If that ice is still pretty white, then it's probably fairly thick and has to be warmed and thinned and finally melted. That process seems to take about 3-4 weeks (just observing).






131
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 03, 2019, 07:54:51 PM »
Okay. Melt ponds. dumb questions?

Can melt ponds drain if the ocean at the ice/water contact is below the freezing point of freshwater (Say -0.5°C). If the ponds can't drain (because the water freezes) then, when ponds do drain, does it imply:

1) That the whole column of ice is at 0°C (warmed through by freezing freshwater)
2) That the ice itself is sitting on water at 0°C, or close to it.
3) Some bottom melt HAS to occur before a melt pond can drain, to warm and reduce the salinity of the ocean that the ice is sitting in.
4) Ice supporting melt ponds has to be thick enough and cold enough to support the pond, and therefore there will be a delay of a few weeks after the blue of the melt ponds disappears before ice melts out.
5)after the melt pond has drained all additional heat is going into melt rather than warming up the ice.

132
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 03, 2019, 07:43:36 PM »
Why does the ocean appear black in MODIS images?

Ocean reflects very little light, even at low angles. It's albedo is 0.06. It's black because of this.

It loses heat by emitting long wave radiation, evaporation and through contact with air. None of which we can see.

If you observe from a very low angle, from a boat, then the color is down to refracted and reflected light. 

133
Greenland and Arctic Circle / Re: Greenland 2019 Melt Season
« on: July 03, 2019, 07:06:12 PM »
sin(30 degrees) = 1/2 is one i use a lot

perhaps we need a thread called quick math trix

sidd

SOOO far off topic. Sorry.

Read Fenyman's autobiography; he had a math race with a guy with an abacus and he uses a number of tricks to win. I believe it's at a time before calculators existed!

My favorite impressive math trick is 1/7ths; 0.142857 recurring.  They are blindingly easy to remember and the reaction to quoting fractions to 10 decimal places in your head is entertaining. My grandpa was a bank manager, and could add up columns of numbers blindingly quickly, far faster than I could type them into a adding machine. He was my role model :)

0.142857... (2x7, 4x7, 8x7 +1)
0.285714...
0.428571...
0.571428...
0.714285...
0.851428...

Its the same sequence, starting from each of the numbers, and the sequence of numbers is trivial to remember.

134
Arctic sea ice / Re: "Stupid" Questions :o
« on: July 02, 2019, 09:33:57 PM »
Is there any reason that arctic sea ice loss should be linear?

I would expect it not to be given that there are feedbacks within the system (i.e. loss of albedo), but I'm wondering if there are arguments for why it should behave linearly?

Thanks

What is the linear relationship you are referring to?
 

135
Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 07:58:51 PM »
I'm more confused than ever - I had thought this season, and from what I've read from the experts, that this year was certainly shaping up to be roughly in the top 5...but after looking at some of the overlays and comparisons it seems as though the pack is not as small (perhaps compact is a better word for it), as I had originally thought. I guess I will wait a bit and see how the melting unfolds the fist half of this month before assuming anything. I think that if the anomalously warm water continues to inundate the basin from the Bering Straight, bottom melt will be quite vigorous.

Extent and area have very poor correlation with the final minimum at this time of the year. You can see just looking at the graphs at how close all the years are during June and July. It's not going to be until August when we might see that all this worrying heat that's being applied to the ice finally melt it out. Think of warming a pan of ice from the base. When will the extent at the top finally disappear? Has enough heat been added to melt the whole thing out, or will there be a thin skin of ice left over the top? Nobody really knows until the whole complex system has had a chance to respond.

136
Arctic sea ice / Re: The 2019 melting season
« on: July 02, 2019, 07:00:21 PM »
Hello, can you look at
https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2019-06-29-T00%3A00%3A00Z&z=3&v=-835137.1514222269,-920779.3466764247,-507457.1514222269,-748875.3466764247&ab=on&as=2019-06-28T00%3A00%3A00Z&ae=2019-07-01T00%3A00%3A00Z&av=3&al=true

it's part of CAA. It was the bluest fast ice I could see. The ponds must have been deep there. And a few days ago it started to be infected by some growing white thing (run animation). Guess it's not much freezing, at around 0-7deg C, and it started from shores and older cracks. Is it pond draining before it disappear maybe then?

When a melt pond forms, water would try to drain through cracks in the ice. When the water below  is cold, the water coming from above would freeze at the bottom of the ice. The melt pond is now sealed, meltwater can accumulate on top.

When the water below the ice is warm though, the sealing effecct will stop. Now the water can drain through the ice freely. I think this is what's going on here.

I'm not sure this is totally correct. The water in the meltpond will seep into cracks in the underlying ice and freeze there as has apparently been confirmed in direct observation. And this will happen even with strong bottom melt ongoing as well, i.e. this freezing is not caused by the underlying sea temperatures, but the internal temperature of the ice. But at some point the structural integrity of the ice is not strong enough, or the internal temperature is not low enough, and the cracks stay open and once the water starts flowing, I guess the cracks will widen very quickly, leading to very rapid loss of surface water.

I suspect its the temperature, even if the ice 'opens' initially the underlying seawater starts the melt season at -1.8°C.; or close to it, depending on the salinity. It doesn't take much refreezing fresh water to warm the ice to > -1.8°C throughout it's thickness. Perhaps we see melt ponds disappear when the ice starts to float on much fresher water (bottom melt, draining melt ponds), so there isn't the available energy sink to refreeze the base of the melt pond. Once the base of the ice/surrounding water is 0°C then the water may drain away.

Rainfall doesn't melt a lot of ice on it's own. 1/83 per °C. 1 m of rain at 4°C only melts 5cm of ice. I think the fact that it isn't falling as high albedo insulating snow is far more important.

137
...

On a slightly more cheerful note i am going to embroider my urn with this:
due to recent more accurate estimates of SSTs that the IPCC SR15's carbon budget to stay below a 1.5C GMSTA will be spent 3 to 5 years sooner that previously assumed by consensus climate scientists.  However, if climate sensitivity is higher than consensus climate scientists assume, then we may have already spent all of our carbon budget and then some.


So thanks!

It is not wise for consensus scientists who calculate Carbon Budgets that underestimate the proven effectiveness of the fossil fuel industry to undermine global climate talks:

Title: "The Fossil Fuel Industry Is Quietly Undermining Global Climate Talks"

https://www.bloomberg.com/news/articles/2019-06-24/the-fossil-fuel-industry-is-quietly-undermining-global-climate-talks

Extract: "Fossil fuel industry giants such as ExxonMobil and Royal Dutch Shell are maintaining an outsized presence at global climate discussions, working to undermine scientific consensus and slow policy progress, according to findings released Wednesday by an environmental monitoring organization.

The Climate Investigations Center (CIC) report claims that fossil fuel trade associations have sent more than 6,400 delegates to climate talks since 1995, including delegates from Shell, BP and ExxonMobil.

“The legacy of fossil fuel corporate impact on the Unfccc process and the IPCC is both invisible and impossible to forget,” said CIC Director Kert Davies in a statement. “Fossil fuel interests have tried from the very beginning to undermine and infiltrate this difficult global agreement to make sure that it failed or faltered at each step. As they win, the planet loses.”"

This has been my experience on a tiny scale. I'm part of the trade association for diesel replacement fuels, and we have a huge budget of $140,000 to spend on marketing. In contrast I was at a posh charity even a month or so ago (filled with the great and the good?) and chevron donated $100,000, just like that; And it's a tiny fraction of the money they spend in California on lobbying. They have unlimited resources. They understand the constituency of every Assembly member, and who there main contributors are. They can make or break a members re-election chances, ensuring who gets voted in tows the party line. I have enormous respect for their ability to bend the legislature to their will. Now that they appear to be winning ground with the unions (refinery workers, oil field workers, etc) it's going to be an uphill struggle just to keep our current legislation in place.


138
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: July 01, 2019, 07:46:27 PM »
After a hard slog through this thread, I decided to pour myself a stiff drink. Dropped a couple of ice cubes in and damn if they did not sink to the bottom of my glass.  ;)

Your drink needs a higher alcohol content.

139
Arctic sea ice / Re: The 2019 melting season
« on: June 27, 2019, 04:39:16 PM »
The GAC welled up heat stored in layers below the Arctic ocean's surface to melt large quantities of ice. Of course, it takes heat to melt ice. Yes, melting ice is a highly endothermic process. The comment you referred to was incorrect and should be disregarded.

Water is a very unusual liquid, it's extraordinarily strongly hydrogen bonded. It's a liquid at room temperature whereas most other compounds with a similar atomic weight are gaseous. When it freezes it forms covalent bonds, and it expands, and hence it's density goes down. Forming those bonds releases energy. When you break those bonds, you have to add energy. The same applies to the transition from liquid to gas, but this time you have to break all the hydrogen bonds that keep it as a  liquid, and that requires much more energy than the transition from solid to liquid.

I'd recommend reading the wiki on water and ice. There are whole journals dedicated to the research of water. Its fascinating stuff....well, I assume, to the other nerds on this forum....


140
Arctic sea ice / Re: The 2019 melting season
« on: June 25, 2019, 07:25:01 PM »
Not a mind reader, but Klondike fits the bill of denier troll. Some give him the benefit of the doubt. Just that he consistently puts himself in the same position.

Best to just ignore him.

You can deny the data all you like, that will not change the results.  There are multiple others here that would agree with me that real story unfolds in the second half of the season.  This is when albedo changes, due to water and clouds have the greatest influence. 

 https://www.the-cryosphere.net/12/3373/2018/tc-12-3373-2018.pdf

If you are stilling unaccepting, check out the data for yourself:  2007 had very low start of the season melt, while 2016 was very high.  Yet both finished with similar minima.  2010 started out with very high early season melt, but tapered off in the second half, bottoming out quite similar to last year, which had a slow start to the melt season. 

http://nsidc.org/arcticseaicenews/

You are right, the ice follow very consistent melt throughout the season, and early ice loss correlates very poorly with the final minima. Using early season extent to divine the end total is difficult at best, a fools errand at the worst.

What matters, in the end, is the amount of energy that gets transferred to the ice throughout the season, a combination of sunlight, warm wet winds, lack of snow cover, and, of course, a good mix with a GAC. This season has been remarkable for heat the ice pack has been exposed to. The results wont be seen until July and August but that doesn't mean its wrong to predict that it will be a bad melt season from what has been observed. Remember that the solar maximum is now, and not in the third week of July, the weather conditions around the solstice are critical for the amount of heat the ice receives.


141
Arctic sea ice / Re: The 2019 melting season
« on: June 25, 2019, 06:28:19 PM »
Hmm.. This might be a stupid question, but in the cool years do we get a lot of snow? I can't think of anything better for ice preservation than a nice, cool reflective insulating blanket. Cold core cyclones dropping snow on the ice must be very good for preservation.

Warm dry air doesn't transfer much heat to the ice, lower specific heat capacity, much lower density. Warm wet air, in bright sunshine, with water condensing on the ice, I can't think of anything better for melt. The situation we have now, with southerly winds blowing over Siberia, land temperatures of 20°C, vaporizing moisture and then condensing it onto the ice must be the worst possible situation. Not so much a hair dryer, but an effective heat pump transferring heat poleward. A swamp cooler for the land, with the Arctic ice being the recipient of the heat.

142
Arctic sea ice / Re: The 2019 melting season
« on: June 22, 2019, 10:59:01 PM »

143
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 20, 2019, 06:11:47 PM »
Re: ruin my economy

There are huge economic opportunities in transition to non fossil carbon energy. Unfortunately the benefits of that transition will accrue to people and entities who are not the current oligarchs of fossil fuel.

Trillions are at stake. Trillions pay for a lot of lies.

In reality the transition will benefit everybody other than those currently benefitting from fossil fuel use. That of course, is not to be tolerated, or so sayeth the barons of fossil.

sidd

This isn't necessarily true. Oil companies in California added sequestration into the LCFS. They can offset their required carbon credits by sequestering carbon.  That's good news for both the economy and for the environment. It's better than most policies, like a carbon tax, that don't actually tie the carbon produced to the carbon put back in the ground using life cycle analysis.

It allows much broader use of petroleum, so fuels like Jet, that are extraordinarily hard to replace, can still be in use. it also allows the LCFS to set lower and lower bench marks for the carbon index of fuels that I can now see getting to close to 0 rather than the current 92. Without sequestration, getting below 80 is an absolute bitch.

It WILL benefit the oil companies. They will get a premium for both taking the carbon out and putting the carbon back into the ground. Who will pay? Consumers, of course, we have to pay for the environmental cost of using petroleum, it will be more expensive, and it's uses will be more specialized, as it should be.

144
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 11:18:49 PM »
Note that condensation of water releases a huge amount of latent heat, enough to melt 7x its mass of ice. Its the difference between 334 J/g and 2230 J/g. In context the heat capacity for water is 4.186 J/g°C.


145
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 19, 2019, 08:47:20 PM »

Monoculture tree planing, especially in grasslands, has been shown to be carbon negative.

We also have to be careful, as the rise in methane recently has been attributed (partially) to increased rot that increase non-linearly with temperature and linearly with precipitation. Any solutions that involve land use change have to be verified to ensure carbon reduction.

Perhaps the best solution is to harvest dead trees, thereby reducing fire risk, burn them for power, and inject the CO2 produced into old petroleum formations.

146
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 06:56:57 PM »

I'm not sure about that, the same thought crossed my mind for the main part of the Arctic as i replied to your post. It's interesting that there is salinity changes where the Arctic is still 'white', though it is apparently wet. Maybe its where we are getting thaw-freeze, any surface melt penetrating into the ice and then refreezing, effectively 'warming' the core of the ice. If it refreezes at 0°C then it can presumably warm the base of the ice enough to melt, and lower the salinity of the seawater. Ideally we would have temperature monitoring through the ice to see when this change happens, but the salinity of the seawater may be a good proxy.


The river input is pretty much consistent year to year and I read that it contributes about 50% of the freshwater (sorry, I can't recall the reference).

For instance the Omolon Delta is one of the inputs into the ESS:

147
Arctic sea ice / Re: The 2019 melting season
« on: June 19, 2019, 06:35:43 PM »

The top layer of the Arctic Ocean freshens through the summer from input from the rivers and from melting ice. First year ice can be as high as 7 psu (practical salinity unit), but it's still much less saline than seawater.

148
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 16, 2019, 07:29:00 PM »
Thanks for the answers gentleman.
I still don’t know if I am a denier or not.
I believe in Anthropomorphic global warming but I still am not sure that the dire results described here by some are close to happening or will ever happen and if I’m wrong about that and the worst case scenario is the correct one, I’m still not sure we can stop it.  I  do know for certain that treaties designed to hurt the US economy while allowing the rest of the world , especially our economic competitors to continue polluting , certainly isn’t the answer.
I will keep lurking and keep asking questions.
I’m on the Board of two charities and active Politically , supporting various different politicians and causes and this often comes up.
I want to know more.

Perhaps geologists are the most worried about climate change. We are well aware that there is enough water trapped in the ice caps to change sea-level by 100's of meters. A small 6m increase similar to the last time the earth was this hot is no big shakes to a geologist, but would be devastating to the 53% of the earths population that live close to coasts. We are pushing the world very quickly towards that state.

The US has perhaps the least to gain from climate change. Much of the Mississippi valley will flood, coastlines will be inundated. 40% of the US population lives in coastal counties. Southern states will be come too hot, farming output will decline. Northern countries stand the most to gain from climate change; Russia will gain the most. If you want to know where Trump's climate policy is coming from I suspect you have to look to Moscow.



149
Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: June 11, 2019, 11:04:04 PM »
Mercator model, salinity 0m vs. 30m for the month of May.

Note that Mercator uses differing scales at different depths. Very annoying.

150
I voted for bin Jun 6-10.

Well that certainly wasn't very haphazard of you. Please could you be a little more random in your guesses? Otherwise I'll be asking Neven to change you name to something more suitable. e.g. "NotVeryHapHazard".

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