From the University of Copenhagen – something interesting, but not really surprising. It does make me wonder though about dust and carbon soot related to Earth’s own polar ice cap. – Anthony
On Mars’s poles there are ice caps of ice and dust with layers that reflect to past climate variations on Mars. Researchers from the Niels Bohr Institute have related the layers in the ice cap on Mars’s north pole to variations in solar insolation on Mars, thus established the first dated climate history for Mars, where ice and dust accumulation has been driven by variations in insolation.
The results are published in the scientific journal, Icarus.
The ice caps on Mars’s poles are kilometres thick and composed of ice and dust. There are layers in the ice caps, which can be seen in cliffs and valley slopes and we have known about these layers for decades, since the first satellite images came back from Mars. The layers are believed to reflect past climate on Mars, in the same way that the Earth’s climate history can be read by analysing ice cores from the ice caps on Greenland and Antarctica.
Solar insolation on Mars has varied dramatically over time, mainly due to large variations in the tilt of Mars’s rotational axis (obliquity) and this led to dramatic climate variations on Mars. For years people have tried to link the solar insolation and layer formation by looking for signs of periodic sequences in the visible layers, which can be seen in the upper 500 meters. Periodic signals might be traceable back to known variations in the solar insolation on Mars, but so far it has been unclear whether one could find a correlation between variations in insolation and the layers.
Correlation between ice, dust and sun
“Here we have gone in a completely different direction. We have developed a model for how the layers are built up based on fundamental physical processes and it demonstrates a correlation between ice and dust accumulation and solar insolation, explains Christine Hvidberg, a researcher in ice physics at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
She explains that in the model the layer formation is driven by insolation and the dust rich layers can be formed by two processes: 1: Increased evaporation of ice during the summer at high obliquity (when the rotational axis tilts down) and 2: Variations in dust accumulation as a result of variations in the axial tilt. The model is simple, but physically possible and it can be used to examine the relationship between climate variability and layer formation.
The researchers established a framework for the model that could explain the layer formation so that it was consistent with the observations. By comparing the layer distribution in the model with precise measurements of the layer structure from high resolution satellite images of the ice cap on Mars’s north pole, they have discovered that the model is able to reproduce the complex sequences in the layers.
Climate history over 1 million years
“The model dates the upper 500 meters of the northern ice cap on Mars, equivalent to approximately 1 million years and an average accumulation rate of ice and dust of 0.55 mm per year. It links the individual layers to the maxima in solar insolation and thereby establishes a dated climate history of the north pole of Mars over 1 million years,” says Christine Hvidberg.
Even though the model is only based on a comparison with the visible layers in the upper 500 meters, preliminary studies indicate that the entire thickness and internal structure of the ice cap can be explained by the model and can thus explain how ice and dust accumulation on Mars’s north pole has been driven by variations in solar insolation for millions of years.
Article in Icarus
http://dx.doi.org/10.1016/j.icarus.2012.08.009
h/t to cui bono
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Mark and two Cats says:
September 6, 2012 at 9:12 pm
“solar insolation” is a pleonasm.
No, it is not. E.g. the solar insolation at the North Pole in the Winter is nil
Leif Svalgaard said:
September 6, 2012 at 9:17 pm
Mark and two Cats says:
September 6, 2012 at 9:12 pm
“solar insolation” is a pleonasm.
No, it is not. E.g. the solar insolation at the North Pole in the Winter is nil
——————————————-
Solar insolation, wherever it is, and whatever its intensity – even if as hot as a burning fire, is always a pleonasm.
“Solar insolation, wherever it is, and whatever its intensity – even if as hot as a burning fire, is always a pleonasm.”
Nonsense, solar insolation varies, the less exact term “solar intensity” could be used, and if we accept that “solar” and “intensity” don’t have the same meaning, how the heck can it be a pleonasm?
Mark and two Cats says:
September 6, 2012 at 9:30 pm
Solar insolation, wherever it is, and whatever its intensity – even if as hot as a burning fire, is always a pleonasm.
No, ‘solar’ can be used with many other things, e.g. solar mass, and insolation need not come the sun, e.g. on the Moon there is significant insolation from the sun and the earth. When humans colonize a planet around another star, they will talk about insolation from that star.
JustMEinT Musings says:
September 6, 2012 at 3:55 pm
Now the big question is how do we tax it? with the second queston being who do we tax?
Tax all foreigners living abroad.
Andrew W says:
September 6, 2012 at 9:46 pm
Nonsense, solar insolation varies, the less exact term “solar intensity” could be used,
Andrew, solar insolation is the correct term, and while that at some time long ago was used only about radiation received from the sun [hence the sol] it should now be used in a wider sense. If [and when] we begin to care about climate on other bodies, e.g. Saturn’s moons, the radiation from the planet is large enough compared to that from the sun that it will make sense to specify where the radiation is coming from, at which time ‘pleonasm’ doesn’t apply. Splitting of hairs [with attended ad-homs] must yield to practical and useful distinctions.
We now have a million year record of solar insolation on Mars. Can we compute Martian axial tilt and precession with a high degree of accuracy? And, once we adjust for that, is there any significant correlation with temperatures on Earth? Timescales don’t appear to be helpful for resolving AGW with Martian data, but there may be enough for paleoclimate comparisons.
Thomas L says:
September 6, 2012 at 11:53 pm
We now have a million year record of solar insolation on Mars. Can we compute Martian axial tilt and precession with a high degree of accuracy?
Yes we can, but we cannot calculate from the ice on Mars what the temperature was with enough accuracy to compare with Earth. Eventually I expect that we should be able to. On the other hand, the true solar variations are much smaller than the changes in the insolation, so it will be a needle in a haystack problem.
Bleh, seemed like a great article until I found the “M” word. Lets take Nasa’s climate budget build another rover and send it to the pole and get some real data.
My mind can’t quite grasp this part: “In this model, layer formation is controlled by the insolation record, and dust-rich layers form by two mechanisms: 1) increased summer sublimation during high obliquity, and 2) variations in the polar deposition of dust modulated by obliquity variations.”
Does this explain how the white layers are formed? How does the snow get up there in the first place?
We have witnessed dust storms on Mars. Are there snowstorms?
Snowstorms suggests some science fiction to me:
In order to have snowstorms you’d have to have evaporation. The thin Martian atmosphere would be altered from mainly CO2 to some sort of CO2-H2O mix. Because H2O is such a great greenhouse gas, the planet would be abruptly warmer, leading to further evaporation and further warming. The moister Mars would lead to fewer duststorms, and then….
When I was a boy all we had looking at Mars were mad scientists up at 3:00 AM, squinting into telescopes. At that hour their eyes seemingly played tricks, and they had pictures of Mars in my boyhood textbooks which showed green areas and “canals.” But…
Suppose there really are green areas, from time to time?
To get a dust layer on ice, or anything else for that matter, you require wind. Dust storms have been seen on the Martian surface but wind is driven by temperature as is ice formation.
Just a thought.
A few years ago (>6) in one of the Astronomy magazines (can’t remember which at the moment) there was an interesting article comparing the variation in the Martian polar caps with those of Earth’s. While the Martian variation was at a lower ‘amplitude’, the growth and decline in the caps did spookily match each other, just a coincidence I guess!
This post reminds me of the saying that “a lawyer who represents himself has a fool for a client”. It sums up the state of climate science where scientists can study Mars with reasonably dispassionate impartiality but are no longer able to do the same with their own environment, the earth.
Unfortunately it is unlikely that alien scientists will ever study the climate of the earth. But were such a thing feasable the aliens would be unnafected by earthly conflicts of interest and politics. They would simply study the earth and its climate with detached, scientific open mindedness.
The aliens would have no preconceived conclusions which they were obliged to promote and therefore their papers would be based solely on the outcome of reliable data. From such data it would be impossible for the aliens to create a CAGW hypothesis.
Would that climate scientists who predict apocalyptic scenarios for the earth, based on primitive computer models infected with erroneous data step back from their emotive reaction to the idea of CAGW and actually practice objective science. I hope that the younger generation of climate scientists, now at university, will reject the establishment’s ‘hockey science’ and return to honest and open scientific research
Lost me at models . . ..
I hate to throw fuel on this fire, but the term “solar insolation” has always bugged me.
Light falling on the moon from the Earth is not (by definition) inSOLation. The term refers to light *from the sun*. Please see http://en.wiktionary.org/wiki/insolation.
In the long term, the sun doesn’t drive Mars’ climate. Mars used to be warmer/wetter when the sun was 15-25% dimmer than now. Changes in atmospheric pressure/composition & orbital changes/planetary tilt are the long-term causes. One should take lessons from that for the earth.
JC said:
September 7, 2012 at 5:25 am
I hate to throw fuel on this fire, but the term “solar insolation” has always bugged me.
————————————–
There’s no fire, I was just pointing out that “solar insolation” is a redundancy – like burning fire, or free gift, or unexpected surprise, or idiot obama.
Just havin’ a little fun 🙂
@Kent C.
” Kent C. says:
September 6, 2012 at 5:40 pm
Isn’t Mars’ atmosphere more than 95% CO2?
If CO2 is a greenhouse gas on Earth, isn’t it a greenhouse gas on Mars?
We are told that a concentration of less than 0.10% (a tiny trace amount) of CO2 in Earth’s atmoshere acts “like a blanket,” or “like the panes of glass in a greenhouse,” to keep the Earth warm.
If such a tiny percentage of CO2 traps head that powerfully on Earth, wouldn’t Mars’ atmosphere of nearly pure CO2 cause heat to mulitiply hundreds of times.”
The pressure of the Martian atmosphere is 6 to 10 millibar. Venus has a substantial atmosphere almost entirely made of CO2 and is indeed scorching hot.
Of course the climate on Mars is driven by the sun. There isn’t anything else to drive it. The core is frozen. More important, the orbit is far more eccentric than the orbit of Earth, which is nearly circular. The eccentricity of Earth’s orbit is about 0.017 whereas the orbit of Mars is ~0.1. That is a major difference and the distance of Mars from the sun varies by a very large amount. That of course changes the solar flux accordingly, by about 46%(!!!). As for any claims that long term global warming is occurring on Mars, that is just plain ridiculous. We don’t have enough data to reach any such conclusion. The martian year is about two Earth years long and we don’t even have a good idea how much difference the dust storms make (a lot). Never mind the fact that the atmosphere is about 100 times thinner than Earth’s and does not transmit or retain heat very well at all…
So, the Sun matters. How inconvenient is that?
“Venus has a substantial atmosphere almost entirely made of CO2 and is indeed scorching hot.”
The surface is, mainly because of the HUGE atmospheric pressure allowing heat to be retained near the surface.
At equivalent atmospheric pressure as those in the Earth’s atmosphere, Venus has almost EXACTLY the temperature it should have according to its closer proximity to the sun..
this is “despite its 95% CO2 atmospheric composition”.
CO2 DOES NOT make the Venusian atmosphere warmer.
Mars’ problem is that it doesn’t have enough atmosphere to hold heat and to try to average the temp between day and night.
And btw.. the Earth’s atmosphere is NOT a blanket. It actually COOLS the Earth’s surface when its too hot.. very odd sort of blanket !!! When the surface is cold and the atmpsphere is still, it does NOTHING !!!! The ONLY way the atmosphere can warm an area is to bring in warmth from a warmer area.. driven by pressure differences. ie WIND !!
CO2 CANNOT STOP CONVECTION, in fact because the specific heat is slightly LOWER than that of ‘air’, it actually INCREASES convection, (very very slightly)
CO2 is indeed a greenhouse gas BUT it is not the only one. The atmosphere of Earth has many important greenhouse gases that contribute to heat retention. Mars just has one and that isn’t enough to cause noticeable warming especially since the thin atmosphere allows very high night sky radiation to cool the planet. The issue on Earth is anything that changes the balance of heat in vs heat out. While change in the amount of CO2 in the atmosphere of Earth is only a small part of the entire picture it is a measurable amount and any change in the amount adds up over time. The system is massive with great inertia so by the time the change is measurable it is far too late to stop in a short time.
Mars is entirely different in that it has little heat storage (no oceans, atmosphere, water vapour) and strong radiative cooling. This combined with the large orbital variation in solar flux makes it very difficult to determine an average temperature. In statistics, averages derived from values with very wide swings are of low confidence value.
[quote]Solar insolation on Mars has varied dramatically over time, mainly due to large variations in the tilt of Mars’s rotational axis (obliquity) and this led to dramatic climate variations on Mars.
Changes in the axial tilt do not change the solar flux intercepted by the planet. WUWT?
[quote]So, the Sun matters. How inconvenient is that?
Inconvenient how? As an explanation for global warming on Earth? Sorry, while the output of the sun does vary it isn’t enough to account for climate change. Solar variation is only enough to account for about 10% of the observed change so far. There is much more to this observed change in climate and it isn’t any single factor. One thing is absolutely certain. Human life on Earth is making a difference to the climate. It cannot be otherwise. That does not mean there aren’t other factors in play. The primary problem in determining what is really going on is the interference with science by politics. It is also necessary to draw a distinction between what you actually know and what you believe. That is most often forgotten and for many the distinction is entirely lost.
Robert of Ottawa says:
September 6, 2012 at 4:38 pm
How to tax the Sun? Easy. Require a hat mandate and fine/tax anyone who does not wear a government regulation hat.
And for those with solar panels fitted to their hats there is a generous grant scheme funded by the taxpayers!
Reblogged this on Public Secrets and commented:
Reality once again plays unfair with the cult of global warming.