Earth's orbit affects the stability of Antarctica's Eastern ice cap

February 3, 2015
Scientific perforation in Antarctica. Credit: CSIC

An international research team led by the High Council for Scientific Research (CSIC in its Spanish acronym) and with the participation of the University of Granada, has found that there is a direct relation between the changes in the earth's orbit and the stability of the Eastern ice cap of Antarctica, more specifically, on the continental fringe of Wilkes Land (East Antarctica). 29 scientists from 12 different countries participated in this study, which has been published in the journal Nature Geosciences.

This study is based upon the analysis of seabed sediments which were transported by icebergs around 2,2-4,3 million years ago, and which have been collected during an expedition of the Integrated Ocean Drilling Program. 

The data obtained reveal that natural climatic processes can increase the response of polar ice caps to minor changes in energy caused by modifications in the earth's orbit. The sea level can either decrease or increase by as much as dozens of metres. This study shows that 2,5 million years ago, when the concentration of carbon dioxide in the atmosphere was similar to the current one, the thawing of the eastern Antarctic ice cap was a generalized process.

"This study helps solve the mystery of how the Earth's orbit around the Sun contributes to the stability of ice caps", according to Carlota Escutia, a researcher at the Andalusian Institute of Earth Sciences (a CSIC-UGR joint institution), which has led the expedition.

Greenhouse effect gases

"The emission of greenhouse effect gases has, nevertheless, a much larger energy impact than that provided by any changes in the earth's orbit", according to Escutia.

The analysis of sediments shows that the stability of the largest ice cap on earth is influenced by the presence of sea ice in the oceans that surround Antarctica. This sea ice is a layer of frozen seawater that creates a protective shield around the continent and the Antarctic ice caps, and it is sensitive to the warming up of oceans generated as a result of the increase in gasses. "The disappearance of this sea ice can result in the melting of the ice caps and in the increase of sea level by several metres", adds Escutia.

Millions of years ago, under conditions of high concentration of carbon dioxide—as is also the case now—and ocean temperatures slightly higher than those currently registered, the oceans surrounding Antarctica could no longer sustain the . Escutia points out that "the disappearance of this protective shield allowed oceanic currents pushed by the winds to penetrate down to the base of the ice caps, provoking their thaw".

This study speculates upon a potentially generalized thaw of Antarctica's Eastern in the future if we fail to reduce the levels of carbon dioxide in the atmosphere.

Explore further: The threat of global sea level rise

More information: M. O. Patterson, R. McKay, T. Naish, C. Escutia, F. J. Jimenez-Espejo, M. E. Raymo, S. R. Meyers,, L. Tauxe, H. Brinkhuis, IODP Expedition 318 Scientists. "Orbital forcing of the East Antarctic ice sheet during the Pliocene and Early Pleistocene." Nature Geosciences. DOI: 10.1038/NGEO2273

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psychosalmon
1.4 / 5 (9) Feb 03, 2015
Funny how as CO2 has increased over the past century the Antarctic sea ice has reached record highs, opposite their findings.
Maggnus
4.7 / 5 (12) Feb 03, 2015
Funny how as CO2 has increased over the past century the Antarctic sea ice has reached record highs, opposite their findings.


That is not opposite their findings, you are comparing apples to oranges.

Here's a little exercise for you - define the difference between a continental icesheet and annual sea ice.
artist1270
2 / 5 (8) Feb 03, 2015
Well shoot, how are they going to tax Middle Class America for the planet's orbit?
Wake
1.4 / 5 (10) Feb 03, 2015
Maggnus - was it just my imagination or were they saying that non-existent "greenhouse gases" were more important than the fluctuations of the orbit of the earth? I suppose throwing the earth about in it's orbit is just like no problem at all.

https://wattsupwi...ical.png

Tell me - do you see any connection between atmospheric CO2 content and mean global temperature?

I have shown through three different sciences that CO2 is NOT a "greenhouse gas" and again and again I see that published as if it were a known fact.
Science Officer
1.9 / 5 (9) Feb 03, 2015
I thought they were going to say that the Earth's orbit is what's causing the seasonal Antarctic sea ice to continue to grow, despite warming ocean temperatures and the "warmest year on record".
ettubrute
3.9 / 5 (11) Feb 04, 2015
When I read through the comments here I had to double check to make certain that I was still on the phys.org blog. I was afraid that I had accidentally ended up on Joanna Nova's blog when I saw the link to an Anthony Watts' image.

psychosalmon, the increase in the Antarctica sea ice extent occurs during the freeze season there. This is when the region has very little to no sunlight and therefore very little to no albedo effect in the region. The sea ice is nearly completely gone, as has been the norm, by the end of the melt season there. This is when the sunlight has more coverage of the region and the waters absorb more of the sun's energy. As more of Antarctica's glacial melt enters the sea this freshens the waters. Fresh water freezes at a higher temperature than does salt water. Too many people are still depending on the psuedo-science websites for scientific information. You are looking for knowledge in all of the wrong places.
Maggnus
4.6 / 5 (10) Feb 04, 2015
Maggnus - was it just my imagination or were they saying that non-existent "greenhouse gases" were more important than the fluctuations of the orbit of the earth? I suppose throwing the earth about in it's orbit is just like no problem at all.
Definitely your imagination. You see, greenhouse gasses are very existent and well kown, and the greenhouse gas CO2 is having a measurable and significant effect on the Earth's climate systems. And while the Earth's progression and orbital eccentricity suggest our climate should actually be cooling now, it is instead warming.

Over the course of millennium however, the three forcings of Earth's orbit will overcome GHG emissions. and a period of glaciation could occur. Depends on how big a role feedbacks play. Well, and how much CO2 we end up putting into the atmosphere.
Maggnus
4.6 / 5 (10) Feb 04, 2015
Tell me - do you see any connection between atmospheric CO2 content and mean global temperature?
Yes, as a driver of global temperatures, atmospheric CO2 content has an affect on global climate. Because CO2 prevents the escape of long wave radiation emitted by the planet, it acts as a kind of blanket, trapping and thereby increasing the energy content of the planet. One of the ways that the energy trapped by this "blanket" displays itself is through higher global surface temperatures.
I have shown through three different sciences that CO2 is NOT a "greenhouse gas" and again and again I see that published as if it were a known fact.
Well then, you are doing something wrong. Three different ways, apparently. It IS a known fact, something that has been known since about 1826 with Fourier's discovery that Earth's temperature is governed by its atmosphere, and certainly no later the 1896 when Arrhenius worked out how higher CO2 concentrations could warm the atmosphere
origin1
1.5 / 5 (8) Feb 04, 2015
That darn man-made orbit change again. We better have the UN come up with a plan.
runrig
4.6 / 5 (10) Feb 04, 2015
Well shoot, how are they going to tax Middle Class America for the planet's orbit?

Sums up your motivation for Denialism in a nutshell "My Tax dollars" ....ah didums
runrig
4.6 / 5 (9) Feb 04, 2015
I have shown through three different sciences that CO2 is NOT a "greenhouse gas" and again and again I see that published as if it were a known fact.

Oh hello, have you really!! amazing
Would you like to looky at this graph my friend...
http://climatekno...stok.gif

And this one from the great Anthony himself...
https://wattsupwi...rge1.gif

And this one from Wiki....
http://en.wikiped...plot.svg

Oh, CO2 DID lag - no longer.
Humbled1
1.7 / 5 (6) Feb 07, 2015
A 1% change in the Earth's perihelion, perhaps due to changes in eccentricity of orbit, would produce a 13 watt INITIAL forcing during perihelion compared to today, without even considering feedback loops. Ignoring albedo feedback loops this is an initial change of about 3C for the equilibrium temperature. Moreover, as eccentricity changes, the Perihelion and aphelion actually occur at different relative times during the year.

It is said that during the Triassic the Oxygen level was about 10% higher as a share fo the atmosphere, and the CO2 level was allegedly 4 times higher simultaneously. They had the largest land animals ever during about this time and the Cretacious, and they had the largest insects and arthropods ever, by orders of magnitude, during this time. Including an ~4 meter long arthropod and a 1 meter wing span Dragonfly, which the present-day Earth cannot sustain a meter sized Dragonfly because it doesn't have enough oxygen to power their flight.
Humbled1
1.7 / 5 (6) Feb 07, 2015
Also, the largest known aquatic reptilians, both salt water and fresh water, existed under higher CO2 conditions, and the largest known fish existed under higher CO2 conditions.

the largest known "modern" bird existed several million years ago, around the same time as this article is talking about, as did the largest known Swine.

However, the largest known land mammal on the whole existed during the most recent ice age, while the largest known aquatic mammal an also the largest known "animal" to ever exist is the Blue Whale. However we should realize that whenever whales die in the deep ocean their remains are typically devoured by scavengers over several years, so they would only be preserved if they were covered over quickly by sub-oceanic quakes. morever they'd usually be subducted under continental crust, so you'd be unlikely to find these remains on land. Maybe check in India or in extinct Estuaries and lakes, like in N. Africa.
Humbled1
1 / 5 (5) Feb 07, 2015
An interesting question is why did the Earth have both more Carbon and more Oxygen in the atmosphere? Did the amount of Oxygen actually change, or did the amount of Nitrogen change?

During such time periods, the oceans would be maximized. There would be more algae, aquatic plants, and planktons in the ocean. There would be more inland seas maintained, presumably, due to more convection producing more rains in different places, so inland deserts might be flooded seas and lakes instead, thus having inland algaes and marshes, etc. Thus more oxygen.

But where did the CO2 come from if this is the case, as it should have been removed from the atmosphere very quickly.

Volcanoes present a problem. The allegation of higher volcanic activity produces the potential for more catastrophism which would undermine the biosphere needed to sustain that oxygen. However prevailing theory is that the asteroid killed the dinosaurs, not a super-volcano.
Humbled1
1 / 5 (5) Feb 07, 2015
Yellowstone is believed to produce a super-eruption every 600,000 years or so. Are we to believe that continents get life-wiped every half-million to a million years or so, yet Dinosaurs somehow survived this and repopulated each continent over and over again for 100 million years, but one Asteroid wiped them all out in a chain reaction that took a year or two?

How do we know they weren't killed by a virus or a bacterium?

All dinos which are found not in a disconformity are below the kt boundary, but this doesn't mean the kt boundary caused their extinction. It just means they were extinct on or before that deposition event.
Humbled1
1 / 5 (5) Feb 07, 2015
According to the "Effective Temperature" article in Wikipedia, some 36K worth of Earth's surface temperature comes from some combination of internal heating and Greenhouse effects.

Hooray for CO2 and Nitrates. We'd all be dead without them.
Humbled1
1 / 5 (4) Feb 07, 2015
Whenever an outer solar system object, such as a comet, collides with an inner solar system object it makes a slight change to the angular momentum of the Earth-Sun system, even though the angular momentum of the Solar System is conserved (approximately adjusted for any explosions or radiation created by the event).

This can change the mass balance of objects slightly, which turn turn contributes to gravity of the objects and the angular momentum also changes the orbit. It may make a difference that is unimaginably small at first but over time this very, very slight change in angular momentum can modify the orbit by noticeable amounts. A mountain sized impactor is enough to change the angular momentum by a factor as large as 1/trillion, which is enough to start to affect the orbital eccentricity and precession over geologic time scales. You wouldn't notice it immediately, it would take tens of thousands of years for the cumulative effects to add up.

Shootist
2.3 / 5 (3) Feb 07, 2015
Something other that Anthropomorphic Carbon effects the climate?

Who knew?
Returners
1.8 / 5 (5) Feb 07, 2015
Something other that Anthropomorphic Carbon effects the climate?

Who knew?


They should consider continental drift. You could warm the South Pole by several degrees and melt most of the ice on Earth just by moving Antarctica northward 15 degrees of latitude into the Pacific.

I seriously doubt greenhouse gases were the primary driver of temperature differences between now and hte Triassic. Instead continental drift and orbital characteristics would be hte primary drivers.
Caliban
4.3 / 5 (6) Feb 07, 2015
Something other that Anthropomorphic Carbon effects the climate?

Who knew?


[...]

I seriously doubt greenhouse gases were the primary driver of temperature differences between now and hte Triassic. Instead continental drift and orbital characteristics would be hte primary drivers.


You are correct, Returners!

And this is precisely what makes our present situation so imminently dangerous, or even outright catastrophic: in the past, climate change was driven, over geologic time, by entirely natural causes...orbital changes, fluctuations in the Sun's output, the occasional supereruption or bolide strike-- but, this time, it is happening at a period when there should actually be overall cooling.

Instead, there is an increase in temperature, due to the emission of hundreds of gigatonnes(and continuing, unabated) of CO2 via the combustion of fossil fuels and deforestation, both of which are virtually entirely human activities.
Caliban
4.3 / 5 (6) Feb 07, 2015
Also,
For any of you who haven't yet made the connection, the main import of the research reported in the article is that continuing increase in the air and water temperatures around the Antarctic are producing so much more melting that the icecap embayment that has, in the past, served to keep the vast majority of Antarctic ice piled up upon the continent, is now giving way, and at an increasing pace.

Which means that glacial ice from the continent is increasingly free to make its way to the sea, where it ultimately melts, raising sea level.

And "several meters" of sea level increase are no laughing matter.

Returners
1.7 / 5 (6) Feb 07, 2015
Instead, there is an increase in temperature, due to the emission of hundreds of gigatonnes(and continuing, unabated) of CO2 via the combustion of fossil fuels and deforestation, both of which are virtually entirely human activities.


We are natural, therefore what we do is natural.

I hope you realize that even when we replace the majority share of fossil fuels with wind and solar there will still be heat waste. Panels are black after all, providing like 0.08 albedo vs 0.3 albedo terrain. If we seriously intend to cover entire deserts with solar panels, well friend, that's a lot of forcing. It might not be CO2 related, but it is there nonetheless.

Wind farms produce a different type of artificial micro-climate by introducing turbulence and weird condensation and fog effects.
Returners
1 / 5 (3) Feb 07, 2015
And "several meters" of sea level increase are no laughing matter.


I would agree. After seeing what happened in Hurricane Isaac, an increase of just 1 meter in the Gulf of Mexico would deeply concern me, and I live north of lakes Maurepas and Pontchartrain. That was a slow moving cat 1. A slow moving cat 2 or 3 on the same track would have put water in my house. The flood maps have been flawed, and Isaac exposed that fact.

1 meter increase in water level would mean that water on average would penetrate about 3 or 4 miles farther inland in Louisiana for any given hurricane strength.

That's LA. There are bigger fish to fry:
Flordia: tampa bay, miami, the keys, pensacola
Texas: everybody from border to border along the coast. Galveston? Goodbye I think.
East Coast: so many metropolis locations and towns and cities heavily affected not just by hurricanes, but east coast upper level systems, nor'easters, etc.

Europe, Asia, etc.
Caliban
4.3 / 5 (6) Feb 07, 2015
Instead, there is an increase in temperature, due to the emission of hundreds of gigatonnes(and continuing, unabated) of CO2 via the combustion of fossil fuels and deforestation, both of which are virtually entirely human activities.

We are natural, therefore what we do is natural.


So you equate intelligent, purposeful human activity with brute natural forces?

Your false eqivalence might be sufficient to allow you, and others like you, to rationalize a hapless, self-imposed, do-nothing stance regarding AGW, but it is a rhetorical device aimed at misdirection, just as the term itself indicates.

Since you go on to detail your concerns regarding the inevitable outcome of warming-induced sea level increase, I suggest that you come to terms with the actual cause of that warming -"Natural" or not.

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