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Are we starting to cool: the case for the last three months


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ET, if it [loss of polar ice] weren't a warming effect then perhaps you can explain why periods of low polar ice are taken, in the historical record, to equate to periods of warmth globally?

I'm quite sure that warming of the globe does result in reduced Arctic sea ice because such warming induces warmer waters flowing into the Arctic circle via the Gulf Stream. However such warming has always gone into reverse sooner or later without any runaway feedback loop such as we often hear speculation about. My curiosity is as to whether the process could be at least partly self limiting if warmer exposed water at or around the north pole increases the rate of overall cooling of the globe and causes the warming process to slow down, cease or even reverse.

Your assessment of flux seems to be making some pretty large assumptions. Yes, there is a net flus from equator to the poles, but much energy is lost en route, hence the thermal gradient is fairly steady polewards: it doesn't suddenly drop off a cliff. The fact remains, more reradiated energy is retained (by the atmosphere) if the oceans are ice free, and in addition less inbound energy is reflected. Any reradiated energy is at a shorter wave length than inbound solar energy. This is the whole point of the debate re GHGs: they absorb energy at shorter wave-lengths. Hence, losing ice starts to have a positive feedback NOT a negative one.

Generally, the larger the temperature difference between the water and the air above it the more heat and water vapour transfers to the atmosphere and then into space. In the arctic, even in summer, the inflowing water from the Gulf Stream is warmer than the air above it. The larger the ice free area the more heat and water vapour will pass into the atmosphere. Ice cover reduces that process.

If you go Google for a few minutes you'll be able to find all the pictures showing typical annual flux. If I remember correctly the energy budget is actually constant the world over: the main driver of surface variation is angle of attack. The J/m2 at the equator is obviously different to the J/m2 at the poles.

The advection of warm water from the south must also be a driver. My point is that in the arctic circle it could well be a stronger contributor to the local heat budget than incoming solar radiation even in summer. In contrast the incoming solar radiation would be the main driver in equatorial latitudes.

Your argument re heat released by the open water would stack up IF all the energy was lost to space. It isn't. In any case, more inbound energy is also absorbed. This is why there is a strong argument for a positive feedback mechanism around polar ice loss.

It doesn't need to be ALL the energy. Just more than would be lost from the reduced albedo. There do not seem to be any definitive figures either way, just an assumption that omits the warm water/cold air aspect.

Not sure the evaporation of water at the poles will be significant in NH snowfall this winter. By far the biggest driver of humidity is evaporation from warm waters, not only are evaporation rates higher, the air - being warmer - can hold far more moisture. The cause of any increase in snow in the NH (and I'm not sure there actually is any more than normal overall) will likely be lower temperatures rather than increased humidity per sé.

There's evidence on line that this years areal snowfall is much increased and there are many reports of deeper than normal mountain snows on all the northern continents.

The warmer waters in the arctic would ,of course, increase northern hemisphere humidity from the evaporative process you mention. Overall cooling of the atmosphere globally from other causes can increase snowfall as well but it does seem more than a coincidence that enhanced snowfall is coming so soon after such a large reduction in total sea ice cover. Especially since there is a 'consensus' that the globe is actually warming from other causes.

Snow on larger areas for longer would increase albedo elsewhere and thus offset the loss of albedo on arctic ice free waters if there is a link between the two. Indeed the arctic being small in relation to the continental areas around it the loss of albedo overall from an enhanced snowfall effect is likely to be greater than the lost albedo from the extra ice free area.

Wavelength of the radiated energy is the vital point.

The vital point is whether, in the arctic, the heat loss to space from exposed water via the atmosphere is greater or smaller than the heat that would have been lost from the albedo effect if that water had been ice covered. The wavelength of the radiated energy simply assists with the calculation but as far as I am aware there is no calculation that takes into account the global cooling effect of warm water advected into the arctic circle.

If you can refer me to such a calculation that may resolve the issue.

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My edit function not working so please note the following correction.

Snow on larger areas for longer would increase albedo elsewhere and thus offset the loss of albedo on arctic ice free waters if there is a link between the two. Indeed the arctic being small in relation to the continental areas around it the loss of ( this was a typo, should have said 'increase of') albedo overall from an enhanced snowfall effect is likely to be greater than the lost albedo from the extra ice free area.

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Posted
  • Location: Steeton, W Yorks, 270m ASL
  • Location: Steeton, W Yorks, 270m ASL
My edit function not working so please note the following correction.

Snow on larger areas for longer would increase albedo elsewhere and thus offset the loss of albedo on arctic ice free waters if there is a link between the two. Indeed the arctic being small in relation to the continental areas around it the loss of ( this was a typo, should have said 'increase of') albedo overall from an enhanced snowfall effect is likely to be greater than the lost albedo from the extra ice free area.

I doubt that last point. Firstly the arctic area is actually fairly large: it's just the normal hemispheric projection of the view of the earth that makes it seem small. Viewed from above the pole the area of ice is massive, and far greater in effect than any ephemeral covering on continental interiors.

...My curiosity is as to whether the process could be at least partly self limiting if warmer exposed water at or around the north pole increases the rate of overall cooling of the globe and causes the warming process to slow down, cease or even reverse.

...

I think you need to think about this some more. For the waters arriving at the Arctic still to be very warm, and given that they do not travel poleward in some vacuum flask like insulated bubble, they would have had to have started very warm. Even if your science is correct as regards the effect at the pole, the investment in energy required to make that context possible is so massive as to suggest that other areas of the earth's surface would need to be very warm indeed.

You're also correct about the flux from surface to air depending on relative difference of energy, however the onwwards flux to space relies on a complex set of interactions, arguments about which lie at the heart of the AGW debate.

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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

It may be possible to argue in the antarctic that increased surface melting without much reduction in extent could possibly have a cooling effect. Here albedo would not significantly reduced but more cold meltwater would go into the sea. This assumes that the ice is just thining and would off course be a limited affect.It is not an argument I think I would want to justify.

Equally you could argue that by the cie melting over the arctic you are more likely to see cloud cover there. You could argue that a semi permanent low level cloud cover could negate any albedo loss due to the ice melt. Again I don't think I would want to justify this arguement not least because I really don't have the number s that would be involved.

A possibility may be that lower levels tend to warm with a result that stratospheric levels cool even further. This would change winter weather patterns (stronger jetstream) with winter cold being locked into the arctic region only. The effects are likely to be somewhat unpredictable.

A distinct possibility is that the deep water sinking points will be disturbed. The artic currently provides calm cool areas where water can sink to the bottom. Remove or disturb those areas and you cause problems for the ocean circulation. This could cut off the feed of warm water and cause the arctic to cool down.

In reality there are so many possibilities and feedbacks that we have to rely on climate models to give some sort of clue.

Arctic circulation chanegs direction

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http://www.wetterzentrale.de/pics/Rtavn125.html

If you look at the above link it can easily be seen how strong is the effect of relatively warm water flowing into the Arctic Ocean. Even now, as we approach the coldest waters of the northern year it is normal for much of the area within the Arctic Circle to remain free of ice with heat being lost to the very cold atmosphere from water that is above freezing.

Even in summer it is the inflow of warm water that transfers equatorial heat to the pole where it transfers via the atmosphere into space.

Nowhere can I find a comparison between the effect of a reduced albedo from summer ice melt set against the additional heat loss from more open water.

The flow of warmth into the Arctic waters from the south is just the same as a bald man not wearing a hat in winter. The Gulf Stream is analogous to his bloodstream.

I do not say that there is necessarily an overall cooling effect from reduced ice cover, just that there might be and that we do not have the evidence to assume either way. However a great deal seems to be predicated on reduced ice cover resulting in a net warming.

I would like to know the truth either way since it is possible that such a process renders

current alarms partly or wholly unnecessary if the global temperature balance is regulated by phases of more or less Arctic ice over time with the reduction in amount being self limiting.

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