Arctic Amplification?

Discussions of the Arctic often include references to “Polar Amplification,” defined thusly by climate scientists (wikipedia):

“Polar amplification refers to the observation that any change in the net radiation balance (for example greenhouse intensification) tends to produce a larger change in temperature near the poles than the planetary average.”

NSIDC adds in the notion of positive feedbacks and concern over “tipping points.”

“Scientists have already seen evidence that positive feedbacks are occurring in the Arctic. They call this Arctic amplification. Predicting the Arctic climate is difficult. Some of the changes in the Arctic could also have negative feedback effects, or effects that reduce the amount of warming. For example, if warm temperatures make the Arctic growing season longer, more plants can survive and take up more carbon from the air. However, most evidence suggests that the positive feedback effects outweigh the negative effects. A recent report by NOAA concluded that Arctic climate is unlikely to return to previous conditions.”

No doubt there is an amplification effect seen in Arctic air temperatures.  This graph by Bob Tisdale presents the evidence:

So what is going on?

Basics of Air Parcels in the Arctic

To begin with, let’s consider the characteristics of the air parcels presenting this effect.

The central region of the Arctic is very dry. Why? Firstly because the water is frozen and releases very little water vapour into the atmosphere. And secondly because (according to the laws of physics) cold air can retain very little moisture.

Greenland has the only veritable polar ice cap in the Arctic, meaning that the climate is even harsher (10°C colder) than at the North Pole, except along the coast and in the southern part of the landmass where the Atlantic has a warming effect. The marked stability of Greenland’s climate is due to a layer of very cold air just above ground level, air that is always heavier than the upper layers of the troposphere. The result of this is a strong, gravity-driven air flow down the slopes (i.e. catabatic winds), generating gusts that can reach 200 kph at ground level.

Arctic temperatures

Temps

Degrees C

Pole

Canada
Chesterfield
Inlet

Coast of
Alaska
Central
Greenland
Spitsbergen

Central
Siberia

Winter
Average -36 -33 -16 -47 -12 -44
January
Absolute -50 NA NA -64 -46 -68
Minimum
Summer
Average 0 4 8 -11 7 16
July
Absolute 13 NA NA NA 21 37
Maximum

http://www.jeanlouisetienne.com/en/images/encyclo/imprimer/11.htm

The heating characteristics of an air parcel

Now consider that raising the temperature of dry air requires 1kJ/kg per degree C. But moist air requires 3 times as much energy, depending upon the air temperature and the saturation amount.

From the Engineering Toolbox:

Enthalpy is the measure of the total thermal energy in air (often called specific heat capacity.)

Energy content is expressed as energy per unit weight of air (Btu/lbair, J/kgair).

Air with the same amount of energy may either be drier hotter air (higher sensible heat) or cooler moister air (higher latent heat).

Moist air is a mixture of dry air and water vapor. In atmospheric air water vapor content varies from 0 to 3% by mass. The enthalpy of moist and humid air includes:
The enthalpy of the dry air – the sensible heat – and
The enthalpy of the evaporated water – the latent heat

Specific Enthalpy of Dry Air – Sensible Heat
Assuming constant pressure conditions the specific enthalpy of dry air can be expressed as:
ha = cpa where
cpa = specific heat capacity of air at constant pressure (kJ/kgC, kWs/kgK, Btu/lbF)
t = air temperature (C)

For air temperature between -100C and 100C the specific heat capacity can be set to
cpa = 1.006 (kJ/kgC)

Enthalpy of Moist Air

The enthalpy of humid air at 25C with specific moisture content x = 0.0203 kg/kg (saturation), can be calculated as:
h = (1.006 kJ/kgC) (25C) + (0.0203 kg/kg) [(1.84 kJ/kgC) (25C) + (2501 kJ/kg)]
= (25.15 kJ/kg) + [(0.93 kJ/kg) + (50.77 kJ/kg)]
= 76.9 (kJ/kg)

http://www.engineeringtoolbox.com/enthalpy-moist-air-d_683.html

The same calculation for moist air at 20C gives a heat capacity of 58.2, so the 5C increase requires 18.7 kj/kg for moist air vs. 5.0 kj/kg for dry air, or a ratio of 1:3.7.  Similar ratios apply at all air temperatures above 0C.  Subzero air, like that in the Arctic most of the year, shows little difference in heat content between dry or saturated, since cold air doesn’t hold much water vapor.

Conclusion:

So there is a physical explanation for why the Arctic air temperatures should warm more than the Northern Hemisphere generally. The same amount of thermal energy applied to the cold, dry air in the Arctic has 3 times the effect on temperatures than when applied to warm, moist tropical air. Not surprisingly, the observed amplified Arctic warming has been about twice the average rate of warming estimated over all latitudes of the hemisphere.

And also, when the trend is cooling the Arctic also amplifies the drop in temperatures. This further demonstrates that polar amplification is a feature of the air itself, and operates independently of CO2 radiative qualities or possible feedbacks from ice or snow extent.

Footnote:

This discussion of enthalpy blends into a point that Roger Pielke Sr. was making years ago.  Moist and dry air at the same temperature has considerably different heat content, as demonstrated above.  And since temperature is being used as a proxy for changes in heat content of the air, to average them while ignoring humidity gives misleading results, especially in places like the Arctic desert.  Dr. Norman page contends that sea surface temperatures are a much better indicator of changes in heat in the global climate, since they are directly reporting enthalpy.

Alpine Amplifier

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Seeing the Arctic Melt without Warmist Glasses

In my Arctic Ice Watch reports I have been tracking progress toward September minimum with graphs like these (data from MASIE):

masie day 230

Doing this after a 3-week break, I was struck by the chart looking a lot like the scoring summary of a tight basketball game, only upside down.

Then AndyG55 commented on my recent summary by linking to this chart from Ed Hoskins:

As the above diagram shows, the temperature balance was pretty close for 7000 years, until the cooling accelerated over the last 3000 years.

My light bulb was in seeing that the summer melt is actually the enormous effort by the ocean to recover water trapped as sea ice in the Arctic. The ice extent varies greatly over the centuries and we know from artifacts that it has been both greater and smaller than presently.  In this time of global warming alarmism, some of us watching the melt season find ourselves hoping for the ice to gain extent, simply to take away that basis for claiming the end is nigh.

Let’s be clear. In this contest between the ice and ocean, we humans should be rooting for the ocean, and so would plants and animals if they knew what was going on. None of us want another ice age, so it is a good thing that the ocean has been gaining on the sea ice extent in the last 150 years.

Once again warmists have got it backwards. The Arctic is a canary all right: The more ice there is in September, the closer we are to the next ice age. Open water in the Arctic is a good thing for the ocean and for the planet.

So taking off the warmist glasses, we should be cheering as the water extent grows and the ice retreats. We don’t wish for a record low because that would drive the alarmists into a frenzy.  Anything around 5M km2 for September would signify nothing unusual is happening, so scary things must be found elsewhere.

Maybe the chart should look like this to emphasize the positives of more water, less ice.

Arctic Water Recovery day 230

Conclusion:
I am not so naive to think that this perspective has much chance against the warmist PR juggernaut. Already the lessening of Antarctic sea ice this year is trumpeted as proof of CO2 warming, and not a celebration of fresh water added to the ocean.

The largest ice cap in the Eurasian Arctic – Austfonna in Svalbard – is 150 miles long with a thousand waterfalls in the summer.

But as Erasmus (1466-1536) said:
In the kingdom of the blind, the one-eyed man is king.

And this one also applies:

Men, it has been well said, think in herds; it will be seen that they go mad in herds, while they only recover their senses slowly, and one by one.
Charles Mackay. Extraordinary Popular Delusions and the Madness of Crowds (1841)

Iceland vs. Greenland, and all that

Why is it that Greenland is mostly ice and Iceland is mostly green?

Many explanations have been offered, usually along the lines of deception: Iceland was so called to discourage others from emigrating, and OTOH Greenland was named to attract others to resettle from Iceland. It seems that after a Viking internal power struggle, the loser and his followers could be banished to leave on a ship to find another land, or die at sea. Thus did Leif Ericsson venture from Iceland to Greenland to found a colony, and later to reach Vinland in today’s Newfoundland.

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Leif Ericsson memorial in front of Reykjavik cathedral.

But it may not be deception at all. When you are off the southeastern coast of Iceland, where the Vikings probably approached, and the sun breaks through for a time, you may be treated to this sight:

Iceland Glacier

Iceland Glacier August 5, 2015 sailing southeast of Iceland.

It happens that the Icelandic glacier sits prominently there, and so, it is land alright, but covered with ice. Of course, later on, they discovered the much more liveable western and southern parts and settled there, but maybe the original name stuck.

Meanwhile in Greenland, I was looking for the icecap and was told by our Inuit guide at Paamiut that you have to sail far up the right fjords to see the ice. Even though 90% of Greenland is ice-covered, that is not what you see from the shore.

Near Nuuk Greenland August 31, 2015

Near Nuuk Greenland August 31, 2015

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