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Donald

A novice question here: as the polar ice cover is lost, there will of course be greater evaporation from the Arctic Ocean. Since some of that water will eventually make its way to the Atlantic or Pacific, won't that tend to increase the salinity of the Arctic, particularly at the surface? Is this effect significant enough to worry about? Or is it only a long term effect?

Thanks, by the way, for a great site.

Steve C

Donald,

Reasonable question. Like most here, I'm just a semi-intelligent, semi-educated amateur. I think the short answer to your question is "yes, but..."

Surface evaporation in the arctic will tend to raise surface salinity, sure. Of course, warmer arctic and pacific waters evaporate more, and for every cubic meter of cold air leaving the arctic with moisture, a cubic meter of air enters, typically with more moisture.

Still, air leaving the arctic didn't have as much moisture when it was all ice-covered. So you might expect changes of the past few years to yield a net decrease in moisture accumulation (and precipitation) in the arctic.

EXCEPT that, as ice has retreated, Atlantic and Pacific have also warmed, yielding more water vapor to the air that enters the arctic (presumably). And thus a net increase of more fresh water to be laid on top of the sea waters.

But really, net deposit of more fresh waster is surely overwhelmed by increases in mixing in the arctic. Water temps, counter-intuitively, go UP as you go down in depth, to a max at around 200 meters. Mixing is powerfully enhanced by waters being open (or covered by broken-up ice) instead of vast solid sheets of ice.

We've seen some temp/salinity profiles discussed here that show some impressive examples of mixing and/or eddies that can occur right down to that 200 m depth.

The paradoxical increase in temp with depth is only possible to maintain because of salinity also increasing with depth. If the salinity gets mixed up, not only do warm waters get mixed at the time/place of mixing events, the breakdown of the salinity gradient allows that warmth to keep convecting up to the surface waters and ice.

This enhanced mixing, with breakdown of salinity gradient, is the prime reason why I expect ice re-growth to be anemic this winter, and spring melt to be enhanced. And this is a powerful feedback for sea ice destruction, a mechanism that could still happen if there were zero net increase in heat accumulation in the arctic.

As it happens, though, sea ice destruction and accumulation of heat in the arctic are mutually-enhancing positive feedback mechanisms.

Timothy Chase

Chris, I am glad that I have been able to return the favor. I have enjoyed your insights a great deal and those of others over the past few weeks. I also like to think that you can reward people by engaging with them, acknowledging their insights, extending them, and further illuminating a given subject. I only wish that I had more to contribute. But this isn't exactly my area of expertise, which I suppose is part of the reason why it interests me.

wayne

William

"as the polar ice cover is lost, there will of course be greater evaporation from the Arctic Ocean. Since some of that water will eventually make its way to the Atlantic or Pacific, won't that tend to increase the salinity of the Arctic, particularly at the surface? "

Mostly not. Often people forget the air is dry in the Polar regions. Current surface temperatures are nowhere near evaporative in nature in the Arctic ocean, Admitting that it warms say +20 C, somewhat like where storms really form, the sun is not as high or non existent for a large chunk of the year, making it still substantially not high on the evaporation scale. However leads among pack ice releases a lot of moisture because of a large water to air temperature difference, Something like 40 degrees during winter as opposed to 10 during the peak of summer.

Chris Biscan

AMSU channel 5 temps are now running near record levels without a NINO.

Chris Reynolds

Donald,

I have to agree with Wayne, although Wayne seemed to call you William. Temperatures aren't so high that it will be a substantial effect when compared to ice loss over the summer. As we approach a seasonally sea ice free state we come to a situation where ice growth over the winter produces ice of the order of 2m thick, this translates to 2m thick of very fresh water mixing into the ocean. Will evaporation remove substantially more fresh water than that? I can't put numbers on it, but I doubt it. That's a lot of evaporation.

Put it this way. In the Arctic would a tub of water 2m deep evaporate dry over the summer?

I've just been looking for references that address evaporation. During the 1950s it was of the order of mm/month. Screen and Simmonds give increases of atmospheric humidity of up to around 0.3g/kg from June Oct between 1989 and 2008. I must admit I can't convert this into evaporation, it doesn't seem to be a trivial matter. But I really don't think evaporation will exceed the freshwater addition from melt of sea ice.

Timothy,
Thanks for the compliment, I always read your comments over here and at RC, whether or not I'm following the matter at hand - I consider you to be someone I can learn from.

Chris Reynolds

This paper is probably better. Figure 9 shows precipitation over watersheds. Of the order of several mm/day over summer. At best evaporation might match freshwater dumping from ice melt.

Kris

Wayne wrote:

nowhere near evaporative in nature

Sorry to say, but to put it (all to) mildly that's not true at all.

There is always evaporation everywhere.

To put to you a blatant example, the Dry Valleys at Antarctica.

Why are the Dry Valleys dry?

The Dry Valleys are dry due to winds coming from 3000 m high nearby mountains.

When going over the top of the mountains the air loses a big percentage of it's humidity.

Then, when descending from the summits the air is so dry it sucks away all of the humidity in the valleys. An accidental cover of snow gets sublimated there in no time. At temperatures between -20 till -70 °C.
And the reverse (= deposition) happens when winds coming from the valleys climb up to the summits

There is always sublimation, evaporation, condensing, precipitation and deposition nearly everywhere in the World. Except perhaps that specific desert in South-Chili of which I don't recall the name for now.

Do have some courses in physics. It would well be worth the while.

Alan Clark

Collincr, I share your disbelief at what people believe who should know better. A few years ago there was a confrontation between Richard Dawkins and a young-Earth creationist who claimed that evolution contradicts the second law of thermodynamics. He was a professor of thermodynamics!

http://en.wikipedia.org/wiki/Andrew_McIntosh_%28professor%29

Donald

Steve, Tim, Chris, Wayne --

Thanks. That was very helpful. I probably will have followup questions later.

For now, I just have an observation that the surface ice has for quite some time acted as a wall (or in 3D like a floor) between two different environments, atmosphere and ocean, and kept the two from interacting with each other except in a very damped way. Now that the wall is being removed, the various models that have been created to explain the special character of the polar environment seem to be losing some of their predictive value, and models generally applicable to atmosphere and ocean in more temperate climates might come to provide some value.

Twemoran

Kris

Your final sentence degrades your post in my eyes. One of the things I appreciate here is the sense of mutual respect between posters. I doubt that I'm alone.

None of us are experts in all of the myriad subjects raised here and it's nice to have a place where speculations aren't met with distain, but rather with helpful suggestions to get us back on the right track.

Thanks
Terry

Timothy Chase

Wayne and Kris,

For what it is worth, the partial pressure of water vapor increases roughly as an exponential function of temperature, even for below 0°C, increasing roughly ~8% for every 1°C, doubling for every 10°C. At 0°C it is 4.6 mmHg, at 10°C it is 9.2 mmHg, at 20°C it is 17.5 mmHg, at 30°C it is 31.8 mmHg, etc. This would mean that at -40°C it would be roughly 1/64 what it is at 20°C, although if I remember correctly, around -20°C it begins to deviate quite substantially from an exponential function, dropping off at lower temperatures more rapidly than a pure exponential function would suggest.

Timothy Chase

Alan Clark wrote:

Collincr, I share your disbelief at what people believe who should know better. A few years ago there was a confrontation between Richard Dawkins and a young-Earth creationist who claimed that evolution contradicts the second law of thermodynamics. He was a professor of thermodynamics!

[Wikipedia: Andrew McIntosh]

I thought that name sounded familiar. Back in 2006-7 I was with the British Centre for Science Education, and McIntosh was/is one of the Young Earth Creationists trying to push creationism into the British educational system. There is more on him at the BCSE, and if you follow the links, a great deal more on other key individuals and organizations in the UK that are trying to push creationism into the schools. You might think that Great Britain wouldn't have a problem with this sort of thing, but there has been a religious revival of sorts in the past couple decades, and a number of wealthy individuals, including US citizen and dominionist Howard Ahmanson who largely funded the Discovery Institute here in the US, have been funding it. In some ways things are tougher in Britain as it has no tradition of the Separation of State and Church.

Timothy Chase

Something I wrote up at the British Centre for Science Education that might be relevant in some ways here...

A conspiracy of silence

wayne

Donald Me bad...

Kris this is what I wrote:

"Current surface temperatures are nowhere near evaporative in nature in the Arctic ocean, Admitting that it warms say +20 C, somewhat like where storms really form,"

Me think its clear enough that I meant that oceans with +20 C give far more evaporation than oceans at 0 C...

Read carefully before passing judgement!

wayne

Timothy, there is so little water vapour suspended in air below -20 C. Since the Arctic is largely at -20 C and colder for a great deal period of the year the air is dry, very dry, so there is a great deal of sublimation especially when temperatures approach 0 in the spring time. Most great Arctic precipitations come from Northwards cyclones originating either in the Pacific or Atlantic. Especially when the cryosphere is frozen at its peak, about March. The idea that the Arctic ocean will replenish Greenland greater ice calving of late by a wide open Arctic ocean is flawed, unless the Arctic ocean sea surface gets much warmer the calving will exceed replenishment.

LRC

I remember an interview I saw one time with a scientist (sorry I can not remember his name), he made a comment that has really stuck with me.
"The difference between a Masters degree and a PhD is not the degree of knowledge, it is that a masters thinks he knows all the answers and a PhD understands that he knows nothing."
He went on to say that to any true scientist even the laws of physics can not be treated as though they are 100% certain. All that can be said that as far as we can test them they always have held true.
That is a point that most non scientist do not understand about the field of science. Does that mean that you then throw all of science or any of science out. No (try your luck at surviving a 1000 ft free fall drop), in fact throwing any science out is dangerous, unless proven beyond doubt does not work, because almost every common formula used by science today did not start out that way. It was worked on and refined. Here we have a 2 fold problem 1) we are dealing with a chaotic system with almost infinite variables, 2) it is non repeatable.

FrankD

Just to expand Kris' point slightly, as the dry air descends from the mountain / plateau it also increases in pressure and warms, thus making the relative humidity even lower. In this specific geographic condition, the katabatic or foehn (similar but different) winds are remarkably dessicating.

This condition does not apply to the Arctic Ocean of course, except perhaps a few points around Greenland.

Timothy Chase

FrankD wrote:

Just to expand Kris' point slightly, as the dry air descends from the mountain / plateau it also increases in pressure and warms, thus making the relative humidity even lower.
So as moist air rises up over the mountain the decrease in temperature, resulting in a rise in relative humidity, as the humidity of saturation against which relative humidity is measured is a near exponential function of temperature. Consequently, the rising air loses moisture through precipitation, much like when maritime air rolls in over the Olympics or Cascades, or as moist equatorial air rises in the tropics as part of the Hadley cell circulation, then subsides in the subtropics, with relative humidity falling with the rise in temperature as the air descends to the surface, giving rise to deserts. And of course in the subtropical deserts the drying out that results reduces moist air convection, raising temperatures near the surface higher, and likewise raising the lapse rate (that is, the rate at which temperature falls with increasing altitude) from the 6.5°C/km average to roughly 9.8°C/km. This becomes more of an issue during heat waves, resulting in positive feedback that makes the heat waves more severe, and will become more of an issue in the United States as the dry subtropics move poleward with the expansion of the Hadley cells under climate change.

wayne

Nice points FrankD and Timothy, but the question was about evaporation in the Arctic, and rather how severe it is with all this open sea water. The Dry Valley argument has nothing to do with this, I don't know why it was injected, its a complete distraction, descending air happens everywhere on Earth.

But Timothy raised correctly partial pressure 4.6 at 0 C and 17.5 mmHg at 20 C... A factor of 5 times less water vapour contained in air. There is no greater evaporation than compared to the South in the Arctic since sea water temperature ranges from-2 to +4 C with air just above varying from -45 to 10 C. None as strong as further South. Here we have it at this moment and for quite a while extremely low snow cover in the Arctic. Again conflicting evidence of important warming twinned with very little snow on the ground. The answer to Donald's question remains the same, until it gets quite warmer in the Arctic evaporation rates will be low. But there is something else, the new wide open Arctic Ocean during summer means that there is a new system in place as to compared with a mere 10 years ago. More sea ice is created than ever before at Arctic refreeze, this has some important salinity issues.

Chris Reynolds

Wayne,

The answer to Donald's question remains the same, until it gets quite warmer in the Arctic evaporation rates will be low. But there is something else, the new wide open Arctic Ocean during summer means that there is a new system in place as to compared with a mere 10 years ago. More sea ice is created than ever before at Arctic refreeze, this has some important salinity issues.

This sums up the situation very neatly. Emphasising that the resultant impacts, within the Arctic land/ocean region, and at lower latitiudes, will vary seasonally.

None of this is simple. Anyone with a single idea, be it atmospheric/oceanic/land in origin is seeing but part of the picture.

But it's all describing the feel of different parts of the same elephant.

Donald

Let me try my question a different way. Consider an area comprised of the Arctic Ocean plus the watershed of all rivers that flow into it. As the ice and snow cover diminishes over the years, will there be a net inflow or outflow of moisture from this area due to evaporation and precipitation? If there is a net outflow, won't this be matched by a net migration of ocean water, primarily from the Atlantic, which would add to the aggregate salinity of the Arctic?

It seems to me that the earlier answers that dealt with freezing and melting do not really address the salinity issue, since it only affects the local mixing of salt and surface water.

Thanks, Donald.

PS My given name is William Donald, but I go by Don, except on my driver's license. So Wayne, your mistake was really pretty funny, to me anyway.

Jim Williams

Donald, the salinity question is rather complicated. The freezing creates pulses of cold salty water which tend to sink and destratify the top water. The melting then creates a fresh water lens which tends to stratify the water. The increased river run-off tends to add to the fresh water lens, and the increased open water available to wind driven convection tends to mix and reduce the salt water lens.

Predicting future Arctic salinity is, to say the least, extremely challenging.

I think the wind will win.

wayne

Don, glad I was funny!

Today this net influx already happens in the form of daily tides from the Atlantic along with other currents. Tides are really under discussed and are really important. The question of salinity is difficult as Jim as written. Stratification should get annulled by winds, and this may delay the refreeze. Also the lack of multi-year ice permitting a huge melt should change all processes because the first year ice which melts is saltier than the old multi-year ice, in this case the saltier Arctic Ocean sea may have started. And its rather smart to have thought of net North Atlantic inflow especially if there is no ice., but we are not there yet, natural feedbacks also include more fresh water rain on the increase in the Arctic. The balance needs to be studied further, but a further reduction of the ice pack during summer may serve the cause of a more open Arctic ocean for a longer period of time.

JanEek

Norway is the leading country when it comes to technology for developing and operating oil and gas fields offshore. No wonder when you take the harsh weather conditions into account and how close we are to the Arctic.

BUT, we are also one of the biggest producer and exporter of fish. Our ocean is one of the most fertile biotope for fish. Before we found oil, our greatest asset was fish. Fish is still a major part of our export. We sell fish to 153 countries worldwide.

One of the richest area for the fisheries is the Barents Sea, but it is also the most vulnerable biotope. It is way up North, in the Arctic.

So, what do we do? We drill for oil and gas in an area with the harshest climate imaginable and with one of the most important source for fishing.

What is this government thinking ? Statoil, the biggest oil/gas company in Norway, has found several very promising oil/gas fields much further south, so we have more than enough produce. AND, we are probably the richest country in the world. The so called oil fund is approaching 4000 billion NOK, and we are around 4.500 people in this country. You do the math……………

So, WHY are we taking the risk of destroying huge parts of the Arctic, including our own fisheries, by developing oil/gas fields in the Barents Sea? ONE large oil spill will be an utter disaster in that area, and because it is so far north, it may take 30, 40 or maybe 60 years to reestablish the biotope to normality. As a fisherman said some years ago: “We can eat fish but not oil”. Simple but true. We must not forget that pumping oil/gas will come to an end one day, but we will always have the fish, and we will be dependent on that simple fact. So, why destroy the most sustainable source of income for our country?

The responsibility for this destructive policy lies wholly in our government. The government consist of three parties: The biggest, the Social Democrats (Arbeiderpartiet), and two very small parties; the Socialist Party (SV) and Senterpartiet, earlier called The Farmers Party. Both SV and Senterpartiet are very conscious and focused on the environment. It was therefore quite a shock when the minister for Petroleum and Energy, Ola Borten Moe from Senterpartiet (!!) stated that we (Norway), will drill for oil and gas up to the North Pole.

What one minister say may not be that important. My main concern is the policy of this government. Drilling after oil and gas in the Arctic is utter madness.

idunno

A new Arctic state...

China declares an interest not in the (Russian patrolled) Northern Sea Route, nor in the (US patrolled) North West Passage, but in the new "Central Arctic Shipping Route"...

http://www.chinadaily.com.cn/sunday/2012-09/30/content_15793745.htm

...which they anticipate to be running straight through the North Pole by 2020. Though the outer lanes, to the North of Svarlsbard, Severnaya Zemlya and the other Russian isalnds, are already open this year...

http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=09&fd=29&fy=1996&sm=09&sd=29&sy=2012

Jim Williams

Idunno, what about the minor issue of the Bering Straight?

Jimboomega

I still think the big question is not about passages being open, or how the arctic itself is changing, but how this impacts the weather in the mid-latitudes, which I still have not seen any good discussion of.

Well, that is not entirely true, I've seen plenty of talk about how a warmer arctic means a weaker polar vortex, stronger jet streams, etc. But specifically how the spectacular melting of the ice has an impact.

I think we are right to look at things like evaporation, salinity, sea level pressures, etc.

One thing I do wonder is if we reach the point where we melt substantially all the ice, will we continue on to a warmer, and more moisture-producing arctic? Just because all the ice is melted, it does not meant that heat stops accumulating.

Ultimately my concern is that a wet arctic really does change patterns in terms of adding more moisture to the air, and that has a variety of teleconecctions. Especially this time of year, when the sun has set, and the air wants to cool rapidly. If the ocean is a much larger source of heat than it was before, what then?

Also looking at some graphs it looks like the "usual" rapid refreeze is getting underway. It's too early to tell decisively, but the gap between 2012 and 2007 is already closing.

Espen

Jimbo,

"Also looking at some graphs it looks like the "usual" rapid refreeze is getting underway. It's too early to tell decisively, but the gap between 2012 and 2007 is already closing."

No, the melt (IJIS) from low September 24 2007 and to date September 30th, is about 40 % lower in 2012 than 2007, I know we counting a few days, but it is an indicator, and it is even from a much lower level!

LRC

Not being an expert at anything, I do have my suspicions. The Atlantic hurricane season could be replaced with longer lasting systems as you will not have the temp differences and the right combinations of other systems. What you will probably start seeing as long lasting more violent cyclones in the Arctic because there you will get all the great conditions for that. What I would find interesting is how that will start effecting ocean currents through there. Now as for the Pacific, That could be interesting as to what happens there, because the cold waters coming off the Antarctic ice sheets will change things up there also.
The big issues with weather from a climate perceptive is that you can give the broad strokes of what to expect world wide, but it is much more difficult to point out what will happen on a more local area although they are starting to get a better handle on that also.

Espen

LRC,

Be careful to use the word "Climate" it is a very sensitive word, it is far better to use "Weather" then we are all "happy"!

dorlomin

http://www.youtube.com/watch?v=VDBO6NSJwK0&feature=g-all-u

LRC

We would need a different word then because weather and climate are not the same thing and I was trying to use them in the context of how they are defined in this forum.

Apocalypse4Real

OT - As the result of the lower ice cover, and higher SST's, I am quite interested in atmospheric methane levels this fall/winter and potential impact on warming.

The Giovanni and IASI methane maps for September 21-30, 2012 are posted. The IASI maps data changed from measuring a range of 970-600 mb to 600 mb in August, 2012.

AIRS/Giovanni:

https://sites.google.com/site/apocalypse4realmethane2012/home/2012-vs-2011-airs-ch4-359-hpa

IASI:

https://sites.google.com/site/apocalypse4realmethane2012/home/iasi-2012-vs-2011-iasi-ch4-970-600-mb

Kevin McKinney

Speaking of 'cool yet depressing,' Kate over at Climatesight has an excellent post. In one modeled scenario in the paper she describes:

The ocean kept absorbing carbon, but in some scenarios the carbon source of the land outweighed the carbon sink of the ocean. That is, even without human emissions, the land was emitting more CO2 than the ocean could soak up. Concentrations kept climbing indefinitely, even if human emissions suddenly dropped to zero. This is the part of the paper that made me want to hide under my desk.

If you're up for more (and it gets worse) you can find it here:

http://climatesight.org/2012/10/02/permafrost-projections/

cyntinadiana

Nice post

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