Opposite Behaviors? Arctic Sea Ice Shrinks, Antarctic Grows
September 2012 witnessed two opposite records concerning sea ice. Two weeks after the Arctic Ocean’s ice cap experienced an all-time summertime low for the satellite era (left), Antarctic sea ice reached a record winter maximum extent (right). But sea ice in the Arctic has melted at a much faster rate than it has expanded in the Southern Ocean, as can be seen in this image by comparing the 2012 sea ice levels with the yellow outline, which in the Arctic image represents average sea ice minimum extent from 1979 through 2010 and in the Antarctic image shows the median sea ice extent in September from 1979 to 2000. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio and NASA Earth Observatory/ Jesse Allen
The steady and dramatic decline in the sea ice cover of the Arctic Ocean over the last three decades has become a focus of media and public attention. At the opposite end of the Earth, however, something more complex is happening.
A new NASA study shows that from 1978 to 2010 the total extent of sea ice surrounding Antarctica in the Southern Ocean grew by roughly 6,600 square miles every year, an area larger than the state of Connecticut. And previous research by the same authors indicates that this rate of increase has recently accelerated, up from an average rate of almost 4,300 square miles per year from 1978 to 2006.
“There’s been an overall increase in the sea ice cover in the Antarctic, which is the opposite of what is happening in the Arctic,” said lead author Claire Parkinson, a climate scientist with NASA’s Goddard Space Flight Center, Greenbelt, Md. “However, this growth rate is not nearly as large as the decrease in the Arctic.”
The Earth’s poles have very different geographies. The Arctic Ocean is surrounded by North America, Greenland and Eurasia. These large landmasses trap most of the sea ice, which builds up and retreats with each yearly freeze-and-melt cycle. But a large fraction of the older, thicker Arctic sea ice has disappeared over the last three decades. The shrinking summer ice cover has exposed dark ocean water that absorbs sunlight and warms up, leading to more ice loss.
On the opposite side of the planet, Antarctica is a continent circled by open waters that let sea ice expand during the winter but also offer less shelter during the melt season. Most of the Southern Ocean’s frozen cover grows and retreats every year, leading to little perennial sea ice in Antarctica.
Using passive-microwave data from NASA’s Nimbus 7 satellite and several Department of Defense meteorological satellites, Parkinson and colleague Don Cavalieri showed that sea ice changes were not uniform around Antarctica. Most of the growth from 1978 to 2010 occurred in the Ross Sea, which gained a little under 5,300 square miles of sea ice per year, with more modest increases in the Weddell Sea and Indian Ocean. At the same time, the region of the Bellingshausen and Amundsen Seas lost an average of about 3,200 square miles of ice every year.
› View larger The ice covering the Bellingshausen Sea, off the coast of Antarctica, as seen from a NASA Operation IceBridge flight on Oct. 13, 2012. Credit: NASA/Michael Studinger
Parkinson and Cavalieri said that the mixed pattern of ice growth and ice loss around the Southern Ocean could be due to changes in atmospheric circulation. Recent research points at the depleted ozone layer over Antarctica as a possible culprit. Ozone absorbs solar energy, so a lower concentration of this molecule can lead to a cooling of the stratosphere (the layer between six and 30 miles above the Earth’s surface) over Antarctica. At the same time, the temperate latitudes have been warming, and the differential in temperatures has strengthened the circumpolar winds flowing over the Ross Ice Shelf.
“Winds off the Ross Ice Shelf are getting stronger and stronger, and that causes the sea ice to be pushed off the coast, which generates areas of open water, polynyas,” said Josefino Comiso, a senior scientist at NASA Goddard. “The larger the coastal polynya, the more ice it produces, because in polynyas the water is in direct contact with the very cold winter atmosphere and rapidly freezes.” As the wind keeps blowing, the ice expands further to the north.
This year’s winter Antarctic sea ice maximum extent, reached two weeks after the Arctic Ocean’s ice cap experienced an all-time summertime low, was a record high for the satellite era of 7.49 million square miles, about 193,000 square miles more than its average maximum extent for the last three decades.
The Antarctic minimum extents, which are reached in the midst of the Antarctic summer, in February, have also slightly increased to 1.33 million square miles in 2012, or around 251,000 square miles more than the average minimum extent since 1979.
The numbers for the southernmost ocean, however, pale in comparison with the rates at which the Arctic has been losing sea ice – the extent of the ice cover of the Arctic Ocean in September 2012 was 1.32 million square miles below the average September extent from 1979 to 2000. The lost ice area is equivalent to roughly two Alaskas.
Parkinson said that the fact that some areas of the Southern Ocean are cooling and producing more sea ice does not disprove a warming climate.
“Climate does not change uniformly: The Earth is very large and the expectation definitely would be that there would be different changes in different regions of the world,” Parkinson said. “That’s true even if overall the system is warming.” Another recent NASA study showed that Antarctic sea ice slightly thinned from 2003 to 2008, but increases in the extent of the ice balanced the loss in thickness and led to an overall volume gain.
The new research, which used laser altimetry data from the Ice, Cloud, and land Elevation Satellite (ICESat), was the first to estimate sea ice thickness for the entire Southern Ocean from space.
Records of Antarctic sea ice thickness are much patchier than those of the Arctic, due to the logistical challenges of taking regular measurements in the fierce and frigid waters around Antarctica. The field data collection is mostly limited to research icebreakers that generally only travel there during spring and summer – so the sole means to get large-scale thickness measurements is from space.
“We have a good handle of the extent of the Antarctic sea ice, but the thickness has been the missing piece to monitor the sea ice mass balance,” said Thorsten Markus, one of the authors of the study and Project Scientist for ICESat-2, a satellite mission designed to replace the now defunct ICESat. ICESat-2 is scheduled to launch in 2016. “The extent can be greater, but if the sea ice gets thinner, the volume could stay the same.”
Maria-José Viñas
NASA’s Earth Science News Team
Gary Lance,
When nobody agrees with you, it is time to re-examine your Belief system. No one agrees with you. You are like the little kid watching a military parade who says, “Look, mom, everyone is out of step but daddy!”
You make such outlandish and provably wrong assertions in your comments that it’s hard to keep up. And it appears from your time stamps that you don’t have a job. Your incessant thread bombing 24/7 is getting tiresome, and violates site Policy.
Note to Gary: everyone else is not wrong. You are. That is validated daily by Planet Earth, which is not doing anything unusual. Your wild-eyed belief in catastrophic AGW is amusing, but it does not hold up under scrutiny.
phlogiston says:
October 26, 2012 at 3:24 am
Gary Lance says:
October 25, 2012 at 8:04 am
“phlogiston says:
The problem with using extent or area is the amount of sea ice can decline, while the extent or area doesn’t. Sea ice that is 5 meters thick and 100% across an area is counted the same as sea ice 1 meter thick and 15% across an area for 5 days when considering extent. In 5 days that sea ice can move a good distance and if the areas are small enough, none of the original sea ice may be left in that area. NSIDC extent data comes from DOD NIC data. NIC data is designed to be analyzed daily and over cautiously to give navigation information to our Navy. As such the data is biased towards sea ice existing, when it might not be and that is done for safety reasons. Sea ice that is white can easily be identified, but sea ice with melt water on top can look like the ocean. The NIC has to devote it’s resources for the next day and isn’t concerned about correcting past data. The NIC has no interest besides daily safety for the Navy. I know this for a fact, because I’ve spoken with people who have done that work. The data sets are turned over to the NSIDC, who has an academic reason to determine if it’s sea ice or not. DMI analyzes the data at 30% concentration and I believe they use a 3 day running average. CT area tries to measure the area that is sea ice. PIOMAS tries to estimate sea ice volume.
However if we are talking about year-on-year trends, then much of the systematic error introduced by differences of method and emphasis will come out in the wash. So something more than a systematic error is needed to account for year-to-year trends, such as the one since 2007 of increased Arctic sea ice maxima.
In general you are clearly very well informed about mechanisms of the recent undeniable Arctic ice decline, no doubt this is your professional field. However it is your implicit assertion that what has been observed over the last 2-3 decades must continue indefinitely, that is really in question. How can you be so sure that these observed changes are not a cyclical phenomenon? An inductive argument that “the GCM models programmed around CO2 AGW predict it” does not really cut it, this inevitably includes an element of circular argument.
I didn’t edit this one.
Why do you keep editing my posts in ways that change completely their meaning? Your “phlogiston says:” is something I said. This is twice in a row you have announced your failure to post something resembling even the reality of this site. It’s little wonder a real scientist doesn’t want to give this place the time of day and deal with these childish troll tactics.
Without man geoengineering, the arctic sea ice is gone and gone, means around 2015. Being very lucky with weather means it happens in 2020. It can’t naturally reverse, because there are too many forces making it that way.
Gary Lance says:
October 26, 2012 at 8:36 am
“Your problem isn’t with a Climate Scientist, your problem is with all real scientists. Only a buildup of CO2 can end a Snowball Earth. The evidence shows an increase in oxygen after Snowball Earth, so where did the oxygen come from if it wasn’t CO2?
“It isn’t Climate Scientists who consider CO2 a major force in a planets climate, it’s all Scientists.”
===========================================================================
The ignorance and stupidity know no bounds. For your information, Gary Lance, positive feedback from ice ball albedo is of three orders of magnitude greater than CO2. Oxygen has never been over 40% –all the forests would burn–but has always been of a concentration many orders of magnitude greater than CO2. The present ratio of O2 to CO2 is 12000:1, and it takes millions of years to make so much oxygen. The notion that sufficient CO2 floated free in the air at any one time to greatly increase O2 content is as absurd as the rest of your science.
Do you really think you’re impressing anyone with anything but your perfect incompetence? Have you no shame? The grade school flunky comes to lecture the professors. Give up already.
–AGF
No, that ratio is 500:1, for the good it will to GL. –AGF
agfosterjr says:
October 26, 2012 at 6:19 am
Gary Lance says:
October 25, 2012 at 3:30 pm
“Is spreading misinformation helping someone? It’s real simple and a known fact that the Cartographers who made the early maps just drew something to represent Terra Australis to fill the void of the empty ocean in areas that weren’t explored. Austrailia was thought to be Terra Australis when it was found and that’s how it received it’s name. When they discovered it was too small, they drew another Terra Australis to fill in the map.”
====================================================
A typical warmist: zero honesty and zero intellect.
I wrote: “Some ancient maps seem to indicate the extent of the southern ice during the LIA. Here’s one:
http://www.gracegalleries.com/images/WOR/WOR159.jpg
Here’s another:
http://www.gracegalleries.com/images/WOR/WOR158.jpg”
If you had taken the trouble to examine the maps you would see the southern shore is intermittent just as the observations are intermittent–just like I said. Too hard to understand.? And like I said, there was a period of more than a century where they gave up on such transitory depictions and showed the the southern ocean as empty–long after Magellan but before the circumnavigation of Australia. Those who know not and know not that they know not–and lie and lie and lie–there’s no way they can be educated. Just keep on fartin’. –AGF
Is there some kind of problem in your brain with separating what you view as a person’s opinion with the person? The topic of this site is not me, so discuss climate science.
Is it a known fact that the southern continents were a myth, which Cartographers added to maps of known areas?
Your point is mute to anyone in academia. You only focused on it to cover up the many other mistakes you made and see how far your ignorance could go.
I keep pointing out, I don’t want to play the troll games of calling people names like Warmists, particularly on a site with a bias. Let’s keep the subject the science, known facts and not the person!
D Böehm says:
October 26, 2012 at 9:27 am
Gary Lance,
When nobody agrees with you, it is time to re-examine your Belief system. No one agrees with you. You are like the little kid watching a military parade who says, “Look, mom, everyone is out of step but daddy!”
You make such outlandish and provably wrong assertions in your comments that it’s hard to keep up. And it appears from your time stamps that you don’t have a job. Your incessant thread bombing 24/7 is getting tiresome, and violates site Policy.
Note to Gary: everyone else is not wrong. You are. That is validated daily by Planet Earth, which is not doing anything unusual. Your wild-eyed belief in catastrophic AGW is amusing, but it does not hold up under scrutiny.
Science agrees with me and not you, but we aren’t the topic that a troll like you keeps trying to make it. If you don’t have something to say about the topic, don’t post!
Gary Lance says:
“Science agrees with me and not you…”
Assertions like that mean nothing.
agfosterjr says:
October 26, 2012 at 9:48 am
Gary Lance says:
October 26, 2012 at 8:36 am
“Your problem isn’t with a Climate Scientist, your problem is with all real scientists. Only a buildup of CO2 can end a Snowball Earth. The evidence shows an increase in oxygen after Snowball Earth, so where did the oxygen come from if it wasn’t CO2?
“It isn’t Climate Scientists who consider CO2 a major force in a planets climate, it’s all Scientists.”
===========================================================================
The ignorance and stupidity know no bounds. For your information, Gary Lance, positive feedback from ice ball albedo is of three orders of magnitude greater than CO2. Oxygen has never been over 40% –all the forests would burn–but has always been of a concentration many orders of magnitude greater than CO2. The present ratio of O2 to CO2 is 12000:1, and it takes millions of years to make so much oxygen. The notion that sufficient CO2 floated free in the air at any one time to greatly increase O2 content is as absurd as the rest of your science.
Do you really think you’re impressing anyone with anything but your perfect incompetence? Have you no shame? The grade school flunky comes to lecture the professors. Give up already.
–AGF
What are you talking about? Oxygen was around 6% before Snowball Earth and did eventually go up to around 34%. You were asked a simple question and that was what ended Snowball Earth.
Time to quit feeding the troll.
From Gary Lance on October 25, 2012 at 5:41 pm:
Dang, just a little bit more searching and you could have avoided looking so foolish. When India hit Asia is actually an issue of some controversy, as covered in the Wikipedia Indian Plate entry:
Etc. Read up on it, India colliding with Asia around 55-50 Ma seems unlikely, significantly after 50 Ma is where the evidence is pointing.
Our new “”expert in everything”” says:
“What are you talking about? Oxygen was around 6% before Snowball Earth and did eventually go up to around 34%. You were asked a simple question and that was what ended Snowball Earth.”
First, nothing in Lance’s reply contradicts what agfoster wrote. Lance’s response amounts to changing the subject, since he cannot refute agf.
Next, regarding the question of what causes the great stadials, no one knows. We have some educated guesses, but they are at most hypotheses.
Finally, scientific skeptics [the only honest kind of scientist] are not obligated to answer questions like that, because skeptics have nothing to prove. The onus is entirely on the alarmist crowd’s conjecture that CO2=CAGW. That conjecture has been repeatedly falsified, not least by Planet Earth — the ultimate Authority.
It comes down to who we should believe: Gary Lance? Or Planet Earth and our lyin’ eyes.
pochas said on October 26, 2012 at 10:28 am:
If you don’t feed the rats, then how do you get them to take their medicine?
kadaka (KD Knoebel):
re your point at October 26, 2012 at 11:29 am
I tried to feed the “medicine” for days – and I used every type of “medicine” I could think of – but the troll just flamed in response.
I suggest the only thing we have not tried is ignoring him. It seems he is only here to gain attention which boosts his low self esteem. Ignoring him will remove his reward so he may go away.
This option has no risks. His statements display such ignorance and his assertions are so outrageously ridiculous that they need no refutation because no onlooker could take them seriously.
Richard
kadaka (KD Knoebel) says:
October 26, 2012 at 11:11 am
Read this and let me see if images work!
http://web.missouri.edu/~hbmq3/images/paleom13.jpg
http://web.missouri.edu/~hbmq3/images/paleom13.jpg
D Böehm says:
October 26, 2012 at 11:27 am
Our new “”expert in everything”” says:
“What are you talking about? Oxygen was around 6% before Snowball Earth and did eventually go up to around 34%. You were asked a simple question and that was what ended Snowball Earth.”
First, nothing in Lance’s reply contradicts what agfoster wrote. Lance’s response amounts to changing the subject, since he cannot refute agf.
Next, regarding the question of what causes the great stadials, no one knows. We have some educated guesses, but they are at most hypotheses.
Finally, scientific skeptics [the only honest kind of scientist] are not obligated to answer questions like that, because skeptics have nothing to prove. The onus is entirely on the alarmist crowd’s conjecture that CO2=CAGW. That conjecture has been repeatedly falsified, not least by Planet Earth — the ultimate Authority.
It comes down to who we should believe: Gary Lance? Or Planet Earth and our lyin’ eyes.
These are simple questions!
How did the Snowball Earth melt without it being CO2?
Where did the Earth get the oxygen after Snowball Earth, if it wasn’t from CO2 and plants?
Run away and don’t answer, but don’t pretend you know science and I need to study!
From Gary Lance on October 26, 2012 at 12:11 pm:
I never said that. You know, with a few seconds of editing you can avoid confusion about who said what. Try it sometime.
That’s as much convincing proof as an image of Mann’s Hokey Stick is convincing proof of CAGW. Now that the existence of credible counter-views has been demonstrated, a one-sided presentation that in no way addresses opposing views nor any controversy, nor even the uncertainty surrounding that singular view, is singularly lacking in persuasive power.
BTW, I’ve seen that image before. When you don’t simply Google for images and actually check the originating sources, you find things like the page where your image is posted, which has many other similar images, and the credit to “Scotese, C. R., 2001. Atlas of Earth History, Volume 1, Paleogeography, PALEOMAP Project, Arlington, Texas, 52 pp.”
Back at the Wikipedia Eocene entry, at the bottom was the link to that image on it’s page on Scotese’s site.
So that yields a 2001 date. If you had actually looked at the linked Wikipedia Indian Plate entry, you would have noticed the opposing views are newer than that, with the excerpt I provided featuring 2012 work.
You’re defending an old view based on old work with an old image, in a dynamic field with new work and new research and new theories still emerging.
The science is not settled. Deal with it.
The Expert On Everything says:
“These are simple questions!”
Questions are always simple. It is the answers that can be very difficult.
And:
“How did the Snowball Earth melt without it being CO2?”
Ah. The ever present alarmist fallacy, the Argumentum ad Ignorantium — the argument from ignorance: “Since I can’t think of any other reason, then global warming must be caused by CO2!” An admission of ignorance.
And:
“Where did the Earth get the oxygen after Snowball Earth, if it wasn’t from CO2 and plants?”
Which proves my point that CO2 was much higher in the geologic past, without ever triggering runaway global warming.
And:
“Run away and don’t answer…” As if, puppy. I don’t run. My MO is to bury your nonsense with scientific evidence, and to show that you have no empirical evidence to support your alarmist belief system.
And:
“…don’t pretend you know science and I need to study!”
No need to pretend, those are both facts.
Gary Lance
I regret that you read devious purpose into my editing of previous posts where none was present. Yes I did cut out chunks of quoted foregoing posts in previous entries – the purpose was only to quote the parts that I wished to address. I agree that leaving “phlogiston says” unnecessarily at the top could be misinterpreted.
While you have undoubted erudition in this field, your frequent repetition of “only a greenhouse gas can end a snowball earth” is really sounding like a religious mantra. It makes no sense. What for instance happened to tectonics? Tectonis continental shifts change ocean currents, and this process must be at the top of the list of candidates for ending a snowball earth. Continental configuration is poorly understood way back in the Huronian. But to take a more recent example, the start of the separation of South America from Africa caused extensive volcanism and a heat excursion which resulted in a mass extinction, marking the boundary between the Triassic and Jurassic.
The assertion that only CO2 can
end an ice age is also seriously challenged by a look at reconstructed global temperatures and CO2 levels during and after the Saharan-Andean ice age at the end of the Ordovician. Here there were tens of millions of years during which CO2 and temperature moved sharply in the opposite direction!
More recently, the ice core record of the last couple of million years of our current glaciation shows that, at each interglacial, the terminating glacial inception is associated with a peak and maximum of CO2 (kind of like now).
Your bruising encounter with kadaka on the subject of the India collision illustrates the fact that AGW scientists generally have a weak grasp of palaeo-history. The main Arrhenius-CAGW hypothesis was framed in complete ignorance of palaeo-climate history. The field of AGW palaeo-apologetics is a recent, rather desperate bolt-on to the AGW narrative.
kadaka (KD Knoebel) says:
October 26, 2012 at 1:53 pm
From Gary Lance on October 26, 2012 at 12:11 pm:
kadaka (KD Knoebel) says:
October 26, 2012 at 11:11 am
Read this and let me see if images work!
http://web.missouri.edu/~hbmq3/images/paleom13.jpg
I never said that. You know, with a few seconds of editing you can avoid confusion about who said what. Try it sometime.
That’s as much convincing proof as an image of Mann’s Hokey Stick is convincing proof of CAGW. Now that the existence of credible counter-views has been demonstrated, a one-sided presentation that in no way addresses opposing views nor any controversy, nor even the uncertainty surrounding that singular view, is singularly lacking in persuasive power.
BTW, I’ve seen that image before. When you don’t simply Google for images and actually check the originating sources, you find things like the page where your image is posted, which has many other similar images, and the credit to “Scotese, C. R., 2001. Atlas of Earth History, Volume 1, Paleogeography, PALEOMAP Project, Arlington, Texas, 52 pp.”
Back at the Wikipedia Eocene entry, at the bottom was the link to that image on it’s page on Scotese’s site.
So that yields a 2001 date. If you had actually looked at the linked Wikipedia Indian Plate entry, you would have noticed the opposing views are newer than that, with the excerpt I provided featuring 2012 work.
You’re defending an old view based on old work with an old image, in a dynamic field with new work and new research and new theories still emerging.
The science is not settled. Deal with it.
I don’t know what wiki has to say, because I never looked it up in wiki. I have scotese for a quick reference, but I just copied an image from google images.
You can tell the continental plates have collided earlier than 50 Ma by the loss of CO2, so prior knowledge was the source of information. To remove CO2 you have to have much mountain building and weathering, more to offset the volcanos it will produce. You people can’t get it through your heads that any Geologist, including all that work for fossil fuel industries, knows there is a relationship between CO2 and climate. It was that way nearly 40 years ago when I took the Geology courses and it’s that way now.
Do you people think you have discovered a scientific breakthrough with your CO2 doesn’t change temperature theory? I think you’re a joke!
From Gary Lance on October 26, 2012 at 12:18 pm:
Milankovitch cycles.
Check the Wikipedia Great Oxygenation Event entry, the rise in oxygen preceded the Huronian glaciation, a Snowball Earth episode, leading theory says the GOE triggered it by converting the powerful GHG methane to the far-weaker GHG CO₂ (although an unreferenced alternative explanation of reduced volcanic activity thus less atmospheric CO₂ is also found at the Huronian glaciation entry).
Also the oxygen came from Cyanobacteria, which use photosynthesis but aren’t plants. Which generate the oxygen waste product from the energy of sunlight by breaking down water. Technically during carbon fixation the CO₂ is used for making carbohydrates.
Actually given the wide range of bacterial life, it seems not only possible that there can be bacteria that expel oxygen which don’t break down CO₂ at all, but their existence is likely at some point in Earth’s history. They could be getting the carbon from methane or other compounds.
I just noticed an article saying that the Antarctic ozone hole might be closing. It would be rather strange if it did and an Arctic ozone hole opened up . . .
D Böehm says:
October 26, 2012 at 2:00 pm
Oxygen was 6%, Troll, and rose after Snowball Earth. Where did the oxygen come from and show us how accurate past CO2 measurements are! Do you have any idea how broad the range on distant past CO2 estimates are?
phlogiston says:
October 26, 2012 at 2:51 pm
Gary Lance
I regret that you read devious purpose into my editing of previous posts where none was present. Yes I did cut out chunks of quoted foregoing posts in previous entries – the purpose was only to quote the parts that I wished to address. I agree that leaving “phlogiston says” unnecessarily at the top could be misinterpreted.
While you have undoubted erudition in this field, your frequent repetition of “only a greenhouse gas can end a snowball earth” is really sounding like a religious mantra. It makes no sense. What for instance happened to tectonics? Tectonis continental shifts change ocean currents, and this process must be at the top of the list of candidates for ending a snowball earth. Continental configuration is poorly understood way back in the Huronian. But to take a more recent example, the start of the separation of South America from Africa caused extensive volcanism and a heat excursion which resulted in a mass extinction, marking the boundary between the Triassic and Jurassic.
The assertion that only CO2 can
end an ice age is also seriously challenged by a look at reconstructed global temperatures and CO2 levels during and after the Saharan-Andean ice age at the end of the Ordovician. Here there were tens of millions of years during which CO2 and temperature moved sharply in the opposite direction!
More recently, the ice core record of the last couple of million years of our current glaciation shows that, at each interglacial, the terminating glacial inception is associated with a peak and maximum of CO2 (kind of like now).
Your bruising encounter with kadaka on the subject of the India collision illustrates the fact that AGW scientists generally have a weak grasp of palaeo-history. The main Arrhenius-CAGW hypothesis was framed in complete ignorance of palaeo-climate history. The field of AGW palaeo-apologetics is a recent, rather desperate bolt-on to the AGW narrative.
There are three known conditions that make the Earth prone to glaciation and two of them we present have. A landlocked ocean and a large continent at the pole are two of those conditions. The third is a large continental mass along the equator disrupting latitudinal currents. We don’t have that and if such a land mass caused a Snowball Earth, it can’t shift and end a Snowball Earth. For one thing it would take many tens of millions of years and the obvious thing is the disruption of latitudinal currents involves transferring heat from the tropics to the poles. Once a Snowball Earth exists there is no heat to transfer. Light doesn’t warm water miles below the ice.
http://resilientearth.com/files/images/Phanerozoic_Carbon_Dioxide.jpg
http://deforestation.geologist-1011.net/PhanerozoicCO2-Temperatures.png
“The immediate cause of extinction appears to have been the movement of Gondwana into the south polar region.”
“The event was preceded by a fall in atmospheric CO2, which selectively affected the shallow seas where most organisms lived.”
Source: http://en.wikipedia.org/wiki/Ordovician%E2%80%93Silurian_extinction_events
The early sun wasn’t putting out the amount of solar radiation like it does today. To start with we have a wide range of estimates for the amount of CO2 in the atmosphere. We have an extinction event presently the second largest in history, which will become third after you guys get done with this one. It’s cause was a hugh land mass moving to the south pole and a drop in CO2.
There are charts that correct CO2 and temperature with factors like reduced solar irradiance, but it’s been my experience that posting such material isn’t allowed on this site, because the google image address mentions other sites that aren’t allowed to be mentioned here.
kadaka says to Lance:
“You perform as well as a trained monkey when given the proper cues. Excellent work, Gary. Have a banana.”
Gary Lance has been b!tchslapped around the block by everybody here. But he continues like Monty Python’s Black Knight: “‘Tis but a flesh wound!” ☺
Having read Gary Lances posts, it seems that he has refuted himself.