Guest Post by Willis Eschenbach
In my continuing wanderings through the regions cryospherical, I find more side roads than main highways. In my last two posts here and here, I discussed the curious inverse relationship between temperature and ice accumulation rates in Greenland and Antarctica.
Wanting to understand the changes in the polar oceans that occur when the sea ice forms, I got to wondering about the albedo changes between sea ice and water. Obviously, ice reflects more sunshine than water does … but how much more does it reflect? It is important because the more the ice melts, the less solar energy is reflected, the warmer the ocean becomes, and this melts even more ice, and so on. This is a positive feedback called the “ice-albedo” feedback, which will tend to increase a given warming. Naturally, the size of this ice-albedo feedback is of interest.
To start with, I looked at the relationship between the “clear sky” albedo and the ice coverage. The clear sky albedo is the albedo measured by the CERES satellite at the top of the atmosphere when there are no clouds in the sky, so it is an estimate of the albedo of the surface itself. Figure 1 shows the relationship between the two variables, for all 1° latitude by 1° longitude gridcells which have ice during some part of the year.
Figure 1. Ice coverage as a percentage of gridcell area (horizontal axis) versus clear sky albedo (vertical axis). The data is composed of the 12 monthly averages for each gridcell. There are 11,646 gridcells (1°x1°) which contain sea ice at some point during the year, meaning that the total number of data points N is 139,752.
It is clear that as the ice coverage increases, so does the albedo. And there is a fairly steep relationship, going from a polar ocean albedo of about 25% with no ice to an albedo of about 55% with complete ice coverage. This is an albedo change of about 30%.
However, that’s just the surface albedo. Of more interest is the “all sky” albedo, which includes the clouds. In Figure 2, I have added the all sky data in blue to the clear sky data shown in Figure 1.
Figure 2. Ice coverage as a percentage of gridcell (horizontal axis) versus both clear (red) and all sky (blue) albedo (vertical axis). The data is composed of the 12 monthly averages for each gridcell. There are 11,646 gridcells (1°x1°) which contain sea ice at some point during the year, meaning that the total number of data points N is 139,752.
The most obvious change is that the slope of the all-sky data (blue) is much less than that of the clear-sky data (red). Rather than a 30% albedo change from no ice to full ice, in the real world there is only about an 18% albedo change from no ice to full ice.
I was surprised to find that the clouds are brighter (greater albedo) than the ice itself. At all different amounts of ice coverage, including 100%, the albedo with clouds is greater than the surface albedo of just the ice itself. (I haven’t thought through all of the ramifications of this finding, I’m just pointing it out.)
However, this still doesn’t tell us just how much extra energy is reflected by the ice. The problem is that in each hemisphere the ice is at its largest extent when there is the least sunlight and vice versa. So what I did was to actually calculate the amount reflected based on the relationship given by the black line in Figure 2, which shows that the change in the albedo is equal to 0.18 times the change in the ice coverage. I calculated for each gridcell just how much difference that ice-based albedo change makes given the variations in the incoming sunlight. This will not be exactly accurate, but is certainly close enough for a first-cut analysis, and is shown in Figure 3 below.
Figure 3. Monthly averages of the total solar reflection from the entire globe (black) and the amount of the reflection that results from the existence of sea ice.
Here we finally have what I started out to find. This shows that on average, sea ice is only responsible for 1.1% of the total solar reflection. This is the result of what I mentioned above, that when there is a lot of ice there is little sun, and vice versa.
Finally, remember that the blue line is the full effect of the existence of sea ice. Let us assume that we get say a 10% reduction in sea ice. This will have 1/10 the effect of the full change, or about a tenth of a percent of the total reflections.
As a result, I’ve gotta say that on a global level at least, even a 10% change in the amount of sea ice makes very little difference to the total reflections. It only makes the total global reflections vary by a tenth of a percent. Now conveniently, total global reflections are about 100 W/m2, so that means that averaged over the planet, if all the sea ice disappeared it would only make a difference of 1 W/m2 in the global reflections … and this means that a 10% change in sea ice amounts to a globally averaged change of 0.1 W/m2
And this, of course, means that the effect of the ice-albedo feedback is vanishingly small globally. It is certainly possible that it makes some larger difference in the immediate neighborhood of the ice, but in terms of a global effect, it is what I call a third-order variable.
Ranking the variables is my own system for trying to understand what is important in a system. I divide variables in a system into first, second, and third order variables. A first-order variable can change the output measurement by greater than 10%. If for example we’re talking about solar reflections, the clouds are obviously a first-order variable.
A second-order variable can change the output by between 1% and 10%. Regarding solar reflections, an example of a second-order variable is snow cover.
Finally, we have third-order variables, which are those that make a change of less than 1% in the output measurement. That is why I said that variations in sea ice reflections are a third order variable. And typically, third-order variables can be ignored in all but the most accurate analyses … and generally we can’t do analyses anywhere near that accurate in climate science.
Anyhow, that’s what I found out about the size of the ice-albedo feedback … it is a third-order variable, so small that it disappears in the noise.
Jupiter burning in the midnight sky, ah, dear friends, another springtime is upon us here, it is good to still be on the upper side of the grass.
My best wishes to all,
w.
My Usual Request: Misunderstandings destroy communication. If you disagree with me or anyone, please quote the exact words you disagree with, so we can all understand the precise nature of your objection. I can defend my own words. I cannot defend someone else’s interpretation of some unidentified words of mine.
My Other Request: If you think that e.g. I’m using the wrong method or the wrong dataset, please educate me and others by demonstrating the proper use of the right method or the right dataset. Simply claiming I’m wrong doesn’t advance the discussion.
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Look – he believes in green house gas theory.
He thinks Angry Bird is a real mathematician
He thinks Rowboat Hansen is a real astrophysicist and programmer
He thinks Phil Jones’ admission he fabricated data with others for over a decade means nothing.
It’s these contrarians who pretend starting argument is scientific discourse when what it is, is trolling. Turning scientific discourse into a game of ”who can act most obtuse and arrogantly ignorant.”
I remember the day the man who released the ClimateGate emails left them and told Mosher stuff it. I looked back at what Mosher had been saying and thought to myself – these fake statisticians are everywhere among these science cons. He’s no different than any of the rest of them.
H. Gutierrez April 3, 2016 at 12:37 am
Look – H. Gutierrez thinks he is above polite requests to quote what he is talking about, and as a result, we have no idea who the “He” is that he is abusing.
Epic fail. Look, folks, I put the following at the end of the post for a reason:
H. Gutierrez, in part the reason is to keep people like yourself from making fools of themselves by spraying spittle around the room while everyone points and laughs at the guy screaming at some unknown unidentified person …
w.
Confessing you’re too stupid to follow a conversation,
then launching engaged, mental illness level, ranting skreed about it,
is something no scientific mind would do.
You don’t have the right to tell people how to communicate. No matter who the f**** you wish you were/hope to become before you die.
It’s particularly ignorant of you to try it when the entire history of mankind has been people fighting, to have other people, not tell them how they have permission, to talk.
You’re something out of another era when because you’re ” __________ ” you can tell people what and how they are to communicate to other people. Whoever you think you are, you need to get it through your head that – the typical real scientific mind doesn’t pay attention to wheedling grammar grannies.
They say what they say, and whoever they say it to, can understand it or not. I wouldn’t ask you for permission to say anything. Who are you? Precisely who are you to tell a stranger you never met that – his previous methodology of speaking isn’t good enough any more, that person answers to you. ?
You’re some kook is who you are, and you’re going to find out if you keep up that kind of behavior, how little people think of that sort of arrogance. We invented the net to STOP your kind of speech control.
Only the insecure join the free exchange of ideas on the modern internet, and believe they have the right to describe how others are to communicate. It’s the mark of the terminal level control freak type intellect.
Adults don’t try to take possession of other adults’ speech that way; the sociologically disordered do.
what seems the most interesting to me in this data is the two clear groups in figure 1. It would be informative to know why there are two groups with notably difference albedo. One of which seems to match the all-sky albedo.
Willis – I’ll ask again, you write that the change in reflection is only 1.1%, but how much would a 3C change in global temperature equate to in percent?
The answer, as I wrote above, is 1%. You should acknowledge that only small changes are required to have significant impacts.
…A 3C increase to 16C would be a 19% increase, NOT 1% !!
Temperature is a measure of the energy in the system and you can only express a % of it by using the absolute Temperature scale, therefore a 3ºC increase is a 1% increase (in T and energy).
Relevant to the Earth’s energy balance is that the loss depends on T^4, so a 3ºC increase represents a 4% increase in radiation heat transfer.
oneillsinwisconsin April 3, 2016 at 3:10 am
While a change of 1% in say global temperature could have large effects, a change of 1% in the amount of rain would make very little difference. You should acknowledge that small changes may indeed mean nothing.
w.
Willis – your post does not discuss a 1% change in precipitation. It does discuss a 1% change in albedo. Albedo is intimately entwined with energy absorption and emission. Now, why I would be asked to admit to some proposition that I never made, but you are (still) unwilling to admit the simple truth that a 3C change in global temperature is a 1% change – a smaller percentage than the 1.1% you ascribe to sea ice reflection – is an interesting subject on its own. It’s part of why I typically avoid this place – rarely a straight answer or correction to errors or ill-conceived ideas. For the record: small changes in unrelated variables or those variables with low sensitivity coefficients have little to no impact on systemic changes. Albedo is not – in the context of the earth’s energy budget – unrelated, nor does it have a small sensitivity coefficient.
You might also wish to inform Marco that you can’t use Celcius to calculate percent changes in temperature. Obviously he’s not willing to listen or learn from me.
oneillsinwisconsin April 4, 2016 at 4:14 pm
Oneill – my post also does not discuss a 1% change in temperature. So why are you rabbiting on about temperature?
3°C is indeed a change of about 1% in global surface temperature … so what? And far from being unwilling to admit that, I’ve made that very point many times when discussing the unusual stability of the global surface temperature. However, my post is about albedo, not temperature. The size of the changes in ice coverage implies a tiny albedo change, nothing like 1%.
Lastly, albedo by itself is a meaningless number. What counts is albedo times incident radiation, which is small in the polar regions.
Not on my posts. I give straight answers and correct my errors. My straight answer is that your claim about a 1% change in temperature has as much to do with albedo as does my claim about a 1% change in precipitation.
“For the record”???
OK, for the record, global ice area since 1974 has varied by ± 5%. This converts to a change in solar reflections of ± 0.05 W/m2 on a global basis. Your attempt to claim that this is somehow important by comparing it to temperature is meaningless. It is freaking five hundredths of a watt per square metre … on what planet is that significant?
Thanks for the offer, but I’ll pass. It’s not my job to correct everyone on the intarwebs, particularly the recalcitrant.
However, you might profitably consider why your attempt to put him on the correct path failed … while it may only be his recalcitrance, it also may not be unrelated to your generally abrasive approach.
My best wishes to you,
w.
Thanks Willis
Allways nice to look at the figures and relations. When searching for anything climate related you get a lot words and very few facts and figures. Like “warming of the globe will melt the ice”.
No one tells that in most of Greenland and Antarctica you need at least 10K warming to start melting any ice at all.
I see this study about energy reflection talking about Greenland and Antarctica.
Greenland being lower in latitude gets more sunlight than Antarctica. There are places in Antarctica that get no sunlight at all or a good couple months so you can’t account for reflection of ice or snow where no light is present. How many W/M^2 of energy is lost in the total darkness of the poles during each pole’s winter months? Over the span of time in this study, what angle of sunlight is being calculated and how much loss of energy in sunlight base on the thickness of atmosphere the light energy has to travel through to get to the clouds and sea ice? Then there is rough water compared to calm that is going to affect the rate of freezing or the rate of overall water temperature drop.
I just don’t see any environmental study like this to be simple at all. There are just so many variables that are in constant flux like the sun angle and spinning earth. I know this study is just one element of light energy and maybe there isn’t space to write a book on all the variables your dealing with to keep this understandable to a layman.
I’m a product engineer that does get involved in testing and have to take in account all variables that could cause failures and get accurate results.
First Willis thank you for your work, and thanks to the reviewers posing proactive comments. My bottom line on all of this is that the science is far from settled and instead of trading carbon offsets we should be investing more in climate research. My very first impulse in response to CAGW many years ago was how of the multitude of factors that influence climate can one molecule be used to define the whole system.
Heaping on to the ice vs snow commentary. Sea ice I’ve seen has been all over the map, ranging from nearly blue in color to white. Once there is a snow pack on top it feeds itself. With a large pack, wind scouring becomes less of a factor, additional accumulation becomes easier, and, the snow compresses at the snow-ice interface, adding to the ice thickness. Ah, NOTHING is ever simple.