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I’m not even sure it works that way anymore. What we’ve seen in the Arctic is that if a pulse of warm water enters the Arctic and melts ice, the effect of having open water to allow cooling by convection, evaporation, and radiation (without the insulating value of ice) is to rapidly reject the excess heat to space. Cooling by radiation on ice can cause the surface of the ice to get much colder, which reduces its radiation rate at T^4, but the ice prevents the cool surface from being re-warmed at a sufficient rate from the water below. Cold water will radiate at a constant level with an emissivity near 1, and the cold water will sink to be replaced by a nearly infinite supply of warmer water just below that. Waves will even increase this radiating surface area. So the radiative (and other) cooling rate of water is much faster than that of ice.
In winter, obviously, there is no solar input at all so the energy removal rate of open water is still much faster than that of ice. The presence of ice is an indicator that there is insufficient warm water underneath to prevent ice formation, in other words, the heat has already been ejected to space by the faster radiative process of open water. In summer, albedo certainly also plays a role, but I haven’t done the math on at what point the cooling capacity difference of open water balances the SWR difference of albedo. Might be a fun exercise though.
It seems that in the Arctic, if you want to remove heat, you open the ocean to do it, and when the process is finished, it will close again. I suspect the sign is wrong on the “polar amplification” effect of albedo since it is outweighed by the cooling effect of open water.
Saying that another way, I think the excess ice in Antarctica is actually preventing warmth from reaching space. It will stay that way until enough heat accumulates under the ice by mixing from other ocean areas to make it open and radiate / convect / evaporate better. The excess ice is a result of overshoot of the previous state of more open water and more effective cooling. Now that the excess heat has been removed, more freezing is a natural result until more warmth can be transported there.
Classic negative feedback…
Michael D Smith-
I agree with you. A while ago I looked at solar insolation by month at 70N latitude using NREL’s solar energy database, versus radiative losses from open water at 0 C.
Open water at 273 K radiates 315 W/m^2.
Average TSI at 71.3N latitude(north coast of Alaska), from NREL-
Jan- 0
Feb- 13 W/m^2
March- 67 W/m^2
April- 154 W/m^2
May- 196 W/m^2
June- 204 W/m^2
July- 188 W/m^2
Aug- 108 W/m^2
Sept- 54 W/m^2
Oct- 21 W/m^2
Nov- 0
Dec- 0
These numbers are even smaller as you approach the N pole.
Downwelling radiation in the Arctic is around 140 W/m^2. Excess downwelling radiation from anthropogenic CO2 accumulated over the last century is 2 W/m^2. As you can easily calculate, the net heat balance with no sun is a loss of 173 W/m^2. The only months that have sufficient sun to prevent re-freeze are May, June and July. Convection dramatically increases the heat loss, and wind-driven spray makes it even larger.
Open ocean in the Arctic winter can’t help but freeze.
Open ocean in the Arctic at the September minimum provides negative albedo feedback.
I agree, Michael! Such negative feedbacks tend to stabilize temperatures, reducing the effect of other forcings, such as GHGs.
There are two scenarios: nighttime and daytime (plus dusk & dawn, when the sun is on the horizon)..
At night, reduced albedo (darker water) allows more longwave radiation to escape from the surface, because albedo is bidirectional: high albedo holds heat in as effectively as it keeps heat out. (That’s why your space blanket is silvered, and why aluminum heatsinks are often black-anodized.)
However, that’s less important than the fact that open water allows more heat to escape from the surface through evaporative and convective cooling.
So sea ice extent is clearly a negative (stabilizing) feedback mechanism when the sun isn’t out. A layer of ice warms the ocean at night, by reducing heat loss, thereby helping to stabilize the oceans’s temperature:
cold air & water -> more sea ice -> more retained heat -> warmer water
When it’s dark, additional sea ice helps the oceans to retain heat that would otherwise have been lost to evaporative cooling, and reduced sea ice increases heat loss through evaporative cooling.
In the daytime, the situation is more complicated, because if the sun is high enough in the sky, ice may have the opposite effect, cooling the water (positive feedback) by reflecting sunlight which would otherwise have been absorbed.
But the net flow of heat in the Arctic is upward (from ocean to air), not downward. The primary source of warmth in the Arctic is not sunlight, it is ocean currents, which exchange frigid Arctic water for less-chilly water from lower latitudes. So my intuition suggests that sea ice is probably a negative feedback mechanism even during during daytime at extreme latitudes, because evaporative and convective cooling probably exceed radiative heat absorption. My guess is that increased heat losses from open water more than compensate for increased heat absorption from reduced albedo.
If you want to analyze the effect of sea ice on total planetary albedo, to see if there are trends which could affect hypothetical “albedo feedback” on sunlight, you need to take into account the latitude and time of year. (Note that since Southern Ocean ice is at less extreme latitudes than Arctic Ocean ice, sunlight hits it at more direct (less acute) angles, so there’s more light per unit area, and less is reflected. That makes Southern Ocean ice more likely than than Arctic ice to be a net positive (amplifying) feedback mechanism during the daytime.)
If you want to know whether a sea ice trend is causing warming or cooling of the oceans, you need to take those things into account, and you need to get a handle on the relative rates of energy transfer, up and down, under ice-covered and ice-free conditions.
It’s not going to be easy to calculate all that correctly, but it should be straightforward to make measurements that settle the question.
One could easily get a good handle on whether sea ice albedo is a net positive or negative feedback mechanism, simply by comparing temperature profiles for water beneath the ice vs. water w/o ice cover, under otherwise similar conditions. If the water averages warmer under the ice, then my speculation is correct, and sea ice acts as a negative feedback mechanism, even in the Arctic summertime. Unfortunately, I can’t find anyone who knows whether that study has been done. I’ve asked that question on both skeptical and alarmist climate blogs, and nobody seems to know.
Aside #1: Contrary to common misconception (e.g., I’ve heard NPR’s Richard Harris say it), sea ice does not reach it’s maximum at the solstice “in the dark of winter.” Sea ice maximums occur approximately at the equinoxes, so the maximums are as important to albedo as the minimums. More important, really, since the maximums last longer: sea ice peaks are “broader” than the minimums, in both hemispheres.
Aside #2: When the sun is low on the horizon, so that sunlight strikes the ice or water at very acute angles of incidence, not much sunlight is available to be absorbed, and even open water is fairly reflective.
Aside #3: If you want to know whether a sea ice trend is causing warming or cooling of the whole planet (rather than just the oceans), it is even more challenging, because additional evaporation from more open water can cause additional cloud cover, increasing albedo at altitude, and additional lake-effect/sea-effect snowfall on land, downwind.
Correction:
I had assumed that, because ice has much higher albedo than liquid water in the visible spectrum, the same was true at longer wavelengths. But I was wrong.
In the IR, both ice and seawater are quite close to blackbodies; ice has slightly lower emissivity than open seawater. For long microwave frequencies, ice has (surprisingly!) much higher emissivity than liquid seawater, which is how passive microwave satellite radiometers can tell the difference between seawater and sea ice. OTOH, ice is generally colder than liquid seawater, which reduces radiation emitted.
The bottom line is I don’t know whether ice cover increases or decreases radiative heat loss. I had assumed that it decreases it, but that might not be correct.
As I stated above, however, the effect of ice cover on radiative heat loss is less important than the effect of ice cover on evaporative and convective cooling, and on agitation of the water. As any competent engineer can tell you, convective (and, when applicable, evaporative) cooling are much more important than radiative cooling under most circumstances.
Ice cover greatly reduces evaporation of the water, reducing the rate at which the water loses heat to the atmosphere. That is a strong negative feedback mechanism. Cold liquid water evaporates much faster than frozen water sublimates even without agitation. Add wave action, and the difference increases.
Additionally, by calming the water, ice cover reduces the transport of energy from beneath the surface up to the surface boundary, which reduces cooling of the ocean, which is another negative feedback mechanism.
Note that these negative (stabilizing) feedback mechanisms operate all the time. Positive (amplifying) albedo feedback operates only half of the time (during daylight).
I think it depends very much on where you measure. If you put a surface temperature measurement station on any piece of land near the Arctic ocean then when the ice is thick, and the sky is clear, and the surface temperature drops due to radiation then any wind will make this low temperature show up at your nearby measurement station. The water beneath may be insulated and relatively warm, but there are very few measurement stations under the Arctic ocean so no one is taking note of that effect.
This of course calls into question what the meaning of a “global average” temperature is, and the answer in practical terms is no meaning at all, but even if it did have a meaning, we are not measuring in even remotely enough places, nor over sufficient time, nor with sufficient consistency to actually construct such an average.
I wish I could give credit where it is due, but a wise man once said that the average global temperature is as useful as a globally averaged phone number.
867-5309
Jenny, is that you . . ?
Preaching to the choir here, but even IF we did have the ability to define and measure an “average” temperature today…. where are the corresponding records from the last 100 years? There is nothing.
Hi Steven,
Pretty interesting that a website titled “skeptical science” bans comments and users who disagree with the agenda. A few years back Cook wrote an article claiming to disprove Joanne Nova’s “Skeptic’s Guide” handbook. I emailed Nova about it, she responded to Cook and Nuccitelli on her website – proving them wrong on every single point. That was almost three/four years ago and they have yet to respond to Nova. Yet, they claim they have the answer to everything global warming related.
I think you put it best a few years ago:
On that website up is down and down is up.
Also, just out of curiosity, do you think human activity has any significant impact on climate (I.e. Temps). In other words, where do you stand on this subject?
I think that human activity (data tampering) at GISS/NOAA/CRU is responsible for most of the reported warming over the past century.
Responses like this are why I love this website.
Mann-made global warming
That’s great ! Classic :o)
It is astounding that this big dirtball survived 4.5 billion years without Man.
Thou shalt not question the Words gushing from AGWer’s mouths, for it is The Truth, even when they offer contradictory Truth later. Deleted Truth is still The Truth, but thou are simply too stupid to see it as so.
Michael D. Smith, I agree with your synopsis. To me the arctic appears to be the planet’s heat dump, precisely as you describe it. Probably the movement of Antarctica to its present position, not allowing seawater near the south pole, keeps earth from being a snowball by preventing a second heat dump.
Cut the poor lad some slack. There are numbers involved here and the requirement to understand bigger and smaller.
Nuttercelli has a long way to go yet to understand such exceptionally complex aspects of number theory.
Wait until he realizes he can count past ten just by taking off his socks . . . That will be a big day for the young lad.
“When ice melts in the arctic more sunlight is absorbed by the ocean.”
And we know that the earth is primarily heated by sunlight that hits the polar regions.
“Essentially Arctic sea ice is more important for the earth’s energy balance because when it increasingly melts, more sunlight is absorbed….blah, blah, blah”
It’s the part of this glib mindless jabbering that says “Arctic sea ice ….when it increasingly melts”, increasingly melts no less! Then what? Refreeze to increasingly melt again? Or does this, oh so important, ice magically put heat at the bottom of the oceans?
Put up a gate
Across Fram Strait
and bottle up that gyre
Arctic ice will build so fast
they’ll ask, “who damped the fire?”
🙂
Prat of the year. Impressive.
http://thepointman.wordpress.com/2013/12/20/climate-prat-of-2013-we-have-a-winnah/
I am baffled by the notion that Arctic water can absorb solar energy at all. Since the angle of the incident solar energy is much less than the Brewster angle for the air/sea water interface, the energy simply bounces off the sea surface (total reflection). That’s why the Arctic ocean looks black.
Simple physics ignored by the ignorant
Good point, but where is the mirror- smooth surface where this would apply?
Only reflected photons make it to the observer’s eye, so total reflection would make the water look white, not black. And obviously if no light were absorbed by Arctic waters there would be no phytoplankton up there, so no food chain, no fish, no whales.
The scientists are right.
Sun is peak in Antarctica with record sea ice near 60S. Record amounts of SW reflection, cooling the planet. SkS are not real scientists, and they are wrong.
1. Water is not totally reflective to light when the incident angle is less than the Brewster angle, nor even nearly so. See the graph in fig. 2 in <a href="“>Cogley (1979); even with the sun at an elevation of just 10° above the horizon, the albedo is less than 40%.
2. The sun can be as high as 46.8° above the horizon at the Arctic Circle.
3. Ocean water is rarely flat, so “the” angle of incidence of the light is really just an average, and the angle of incidence of any particular photon can be anything from zero to 90°.
John wrote, “Simple physics ignored by the ignorant.”
Be careful about throwing stones.
If the sea ice is making a big recovery from a record low, so what? The net amount of global land ice is decreasing. We know this because there’s no other way to explain why ocean levels are rising year by year. That extra water can only come from melting glaciers and ice sheets. This is exactly what you’d expect if the planet as a whole is warming.
Global sea ice area is second highest on record for the date.
Sea level has been rising for the past 20,000 years regardless of whether the temperature has been rising or falling . Sea level rises during interglacials and falls during ice ages.
You can’t infer warming or cooling from small changes in sea level. Does the ice in your glass only melt if the temperature is rising?
So if net global glacial/ice sheet melt is not being caused by rising temperatures, what could be causing it?
Chris, 65% of tide gauges either show no sea level rise or show sea levels falling…
That’s not quite right, Latitude. About 3/4 of the GLOSS-LTT gauges that NOAA has analyzed are showing at least a little increase in sea level. But the rate hasn’t accelerated at most of them in at least 80 years.
This new paper says 65%….
http://pluto.mscc.huji.ac.il/~msdfels/wpapers/Tide%20gauge%20location.pdf
I haven’t read that paper, but I suspect it means decelerating, not falling. Decelerating means rising at a decreased rate or falling at an increased rate. In most cases it means rising at a decreased rate.
I like to put it this way: Take an ice cube from the freezer and set it on the counter. Soon, it begins to melt. If you now move it to the refrigerator, does the melting stop? Diminishing ice doesn’t depend on rising temperature. The world could have been cooling for 80 years or more (and probably has been) yet any ice accumulation that is out of equilibrium will continue to melt.
Let’s take some of that Greenland ice- melt and pump it over to replenish the Ogallala Aquifer which is being rapidly depleted to water the corn to make the ethanol necessary to save the planet.
That’s true, Chris. But sea level is rising no faster now than it was 80 years ago, which was before mankind had much effect on GHG levels. So you can’t attribute the current rate of sea level rise to human GHG emissions, and curbing human GHG emissions can’t be expected to slow sea level rise.
Nice argumentum ad ignorantiam, Chris.
AHHH, but Nutty forgets what the reactivation of the Bipolar seesaw means. From a peer-reviewed paper from last year.
This means we are already in the descent curve into the next glaciation therefore the ‘Science’ says BURN MORE COAL! :>)
Does anyone here have email addresses for most of the SKepticalScience “team?” I’ve managed to find only a few of them.
Sikse