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
From D. J. Hawkins on October 24, 2012 at 11:39 am:
So do I. That was pedantic nitpicking about the absoluteness of “6 months of no energy input”. There’d be a net energy loss, but still energy inputs.
Keith Distel @ur momisugly October 24, 2012 at 8:51 am
Re: active volcano on the Antarctic Peninsula. There is one on Deception Island that destroyed a couple of research stations in the 1960’s. Also erupted in 1987 (wrongly stated as 1970 in Wikipedia).
http://en.wikipedia.org/wiki/Deception_Island
“higley7 says:
October 24, 2012 at 7:28 am
“shrinking summer ice cover has exposed dark ocean water that absorbs sunlight and warms up, leading to more ice loss.”
Sunlight in the Arctic at the height of summer is only 3% of normal sunlight as it comes in at a low angle and through a greater distance of atmosphere (the W/m^2 is down 97%). Any heating of the water will be near the surface and will be rapidly lost to evaporative cooling.”
The North Pole gets more sunlight at the height of summer than the equator. Hint: It’s getting it 24 hours per day.
The arctic wouldn’t be ice free throughout the year immediately after becoming ice free, but the alligator fossils in Alaska tell a different story about it won’t be ice free year round and the continents were basically as they are today. Recent findings also show ice sheets can melt much faster than once thought. If we lose the arctic sea ice, Greenland will quickly melt, but overnight. I expect to see more of those 2012 melts in the future, maybe next year. The reason has nothing directly to do with the sea ice, it has to do with the June snow cover in the Northern Hemisphere being nearly 6 million square kilometers less than the base period.
http://daisy.sodor.no/generated/36311_sn__dekke.jpg
That snow cover loss is on the order of 3 times the area of Greenland or 3 times the area of the 2012 arctic sea ice minimum. Those lands aren’t oceans that can absorb nearly all the solar radiation, but northern areas can become quite warm if they aren’t covered with snow reflecting sunlight and the sun is most intense. Air masses travelling over such places can remain warm and large warm air masses will find their way to Greenland causing melt.
Once the arctic is ice free, it won’t have to bother melting multi-year sea ice and first year sea ice will melt away quickly each year. The top 50 meters of the arctic has low salinity and a lower temperature, but waves and storms are going to mix that up. The Arctic Ocean will tranform to a temperature gradient ocean, like the rest, instead of one based on salinity.
How soon it will become ice free year round is hard to say, because that northern area has unusual clouds and fog and it’s hard to predict how that will evolve. The climate has to change, so I would expect the old AO high to move to Greenland and I also expect the currents to change. There is still a lot of melting to do with permafrost and Greenland until all heat becomes dedicated to warming oceans, land and air. In a hundred years, I’d say there would be trees able to grow in once tundra next to the Arctic Ocean, but the alligators might have to wait a little bit.
Some European says:
October 24, 2012 at 12:20 pm
“There’ll be open water in the Arctic and a glacier-free Glacier National Park (in ten years) and you guys will still be fantasizing evidence for global cooling / no warming / warming but not man-made / maybe man-made but not harmful / possibly problematic but I don’t like hippies and government regulation / a huge catastrophe but it’s too late now so let’s enjoy the party while it lasts.”
============
No reference to the demise of a cute critter ?
No mention that ice is an enemy, with almost no equal ?
To imagine that production of a trace gas, could affect a planet that raises mountain ranges only to have them washed into the sea, seems to indicate a lack of perspective.
Other than a sudden party crasher, She is only playing out perterbations put into the system long ago.
Sorry, it is not about you.
At first sight opposite ice trends at the to poles are suggestive of the bipolar seesaw associated with both the beginning and the end of an interglacial. However closer reading of the paper by Tzedakis on this:
http://www.clim-past.net/8/1473/2012/cp-8-1473-2012.pdf
shows that, evidently, the bipolar seesaw is only reactivated 3 kYr after an interglacial is already ended.
A low magnitude bipolar seesaw might be a permanent feature, possibly due to the higher-than-cloud albedo of the white-than-white Daz automatic snow in Antarctica, so that increasing cloud warms Antarctica but cools the rest of the planet.
In any case, it is likely that Gary Lance’s wait for Alligators in the Arctic will be about as long as another Lance’s wait for another Tour do France medal.
“Recent research points at the depleted ozone layer over Antarctica as a possible culprit.”
Fact check follows.
1. Annual maximum size of Antarctic ozone hole is pretty stable since 1989 (last 24 years).
2. The same is true for annual minimum ozone concentration (in Dobson Units)
3. Production of halocarbons decreased dramatically since the Montreal Protocol was signed (1987)
3. The Antarctic ozone hole is a spring phenomenon (September – November)
4. Antarctic sea ice cover has increased over the last 2 decades in spite of stable ozone levels
5. Sea ice increased in all seasons, even in those with no ozone hole
6. 2012 summer (February) ice cover being 251,000 square miles over average is not a “slight increase” (it is 23% over average).
7. In summer there is no ozone hole whatsoever over Antarctica
8. Air over Antarctica is very dry, therefore water vapor couldn’t mask effect of CO₂ if there were any
9. CO₂ concentration over Antarctica is increasing at the same rate as anywhere else
Now, these facts are inconsistent with claims
a. Antarctic sea ice increase is caused by ozone depletion
b. ozone depletion is caused by overproduction of halocarbons
c. increasing CO₂ concentration traps significant amount of thermal radiation to space over Antarctica
Whenever claims are inconsistent with facts, claims should be abandoned.
One more thing. Honest research either proves or disproves something or, as a last resort, leaves the question open, but never points at anything as a possible culprit.
Because what’s the proposition here to which a truth-value should be assigned? It must be “Depleted ozone layer over Antarctica is pointed at as a possible culprit”. Now, what’s the negation of this proposition? For, if the negation of a proposition is proven to be true, the proposition itself is surely false. However, unfortunately it sounds like this: “Depleted ozone layer over Antarctica is not pointed at as a possible culprit.” And this one is certainly false, because the phenomenon is in fact pointed at. By the researchers themselves. And then, we have not even ventured into the murky depths of modal logic implied by the presence of the phrase “possible culprit.” Neither did we scrutinize usage of the term “culprit” in an impersonal context.
with all the recent papers on cosmic rays and their putative effects on clouds and such, I have to wonder if there is some issue with the solar system’s position relative to the galactic plane. As you know, we cycle above and below the galactic plane in a regular rhythm With more or less bombardment of [fill in the blank] you get more or less polar ice. I’m not well read in this area so I would hope someone who is can take a whack at this idea. Perhaps it is nothing.
Berényi Péter says:
October 24, 2012 at 2:37 pm
Are you saying they can’t measure wind speed and notice it has increased? Are you saying they can’t measure precipitation and notice more snow on sea ice, when they land on it? They said the snow was so thick it cracked the sea ice and allowed ocean water to thicken the sea ice. 1 meter sea ice is only 4 inches above sea level. It doesn’t take much snow to weigh it down and flood that.
It’s first year sea ice and it all melts away, except for a small amount that gets saved in the Ross and Weddell Sea gyres. The antarcitic is essentially sea ice free at it’s minimum.
As far as you ozone nonsense, they only said they thought it might be because of the ozone. If the ozone is speeding up the circumpolar wind, it can speed up the circumpolar current with time. Once the current speeds up it has it’s own momentum. It’s stronger than the Gulf Stream.
The antarctic sea ice gets a little crazy at it’s maximum, though it didn’t do it last year for some reason. I expect this year to be like all others and the sea ice will melt following the average. The trend has been to be above average as the sea ice is forming and be right on the base average once serious decline begins. You aren’t going to find charts drawn comparing the antarctic sea ice minimums, because there really isn’t a trend there and the minimum all depends on the weather at that time. I’ve seen archived satellite data of both gyres being cleaned out of sea ice and I’m sure it will happen again. That’s when the antarctic sea ice will reach an all time record minimum, but it will bounce back, because the gyres protect the sea ice.
Yesterday’s news reports of the ice melting on Australia’s Antarctic airstrip are relevant to this discussion.
But unexpected surface melt has sharply curtailed use of the summer airstrip.
http://www.canberratimes.com.au/environment/climate-change/antarctic-airstrip-melting-away-20121023-283kx.html
They have made a small area of Antarctica, like the Arctic by planes depositing black carbon on the ice surface and then the surface melts.
Friends:
Gary Lance says at October 24, 2012 at 3:25 pm
It is a pity that he does not know the minimum Arctic sea ice is also determined by the weather.
Richard
RE: “At first sight opposite ice trends at the to poles are suggestive of the bipolar seesaw associated with both the beginning and the end of an interglacial.”
This. Be scared. Be very scared. No, not about that … about the other thing, the unmentionable thing.
Philip Bradley says:
October 24, 2012 at 3:41 pm
===========================
BBC, in concert with a number of media outlets announced today that global warming was melting the Wilkins ice runway in Antarctica. This announcement lends itself to examination of the nature of media behavior regarding global warming–what is really happening and where? First of all one might wonder, what season is it in Antarctica as I write this response? Our October is equivalent to the South Pole’s April. Summer has not yet arrived, yet runway meltdown is announced. And just a little digging brings up the source story, from January of this year in the Tasmanian “Mercury.” It turns out that last summer, nine months ago, the ice runway had its second season of extra warm weather, which prevented its use in January.
Australia spent some 40 million dollars on this asset, and so far only a few dozen flights have been made from Tasmania, thus costing about a million dollars per flight so far. The fact that the runway is only four years old leaves us to wonder, how much has the planet warmed in the last four years, and didn’t these planners know about global warming four years ago? And are they absurdly blaming on global warming what is really the result of their own incompetence? Or have they just had a couple of years of bad luck with the weather? After all, we’ve had over a decade with no global warming to speak of.
So no, global warming is not responsible for the limited usefulness of a nearly new ice runway, and no, this is not spontaneously generated news of a recent event. Rather it is the calculated propaganda of a consortium of radical environmentalists–who understand that there’s a sucker born every second–and gullible or complicit journalists. Take an old story, dress it up in the garb of long term climate change, and the media will eat it up. And most of the people will believe it. Shame on the fools! –AGF
From Gary Lance on October 24, 2012 at 1:45 pm:
http://www.sciencedaily.com/releases/2010/08/100824132417.htm
The Arctic was warm enough for alligators in the past. Ellesmere Island, adjacent to Greenland, was swampy.
Yet somehow there were not tipping points that were passed that lead to catastrophic life-destroying global warming. Life went on.
Even though Ellesmere Island was so warm yearlong that an Arctic Ocean that was ice-free year round not only seems possible, but most likely.
Philip Bradley says:
October 24, 2012 at 3:41 pm
Yesterday’s news reports of the ice melting on Australia’s Antarctic airstrip are relevant to this discussion.
But unexpected surface melt has sharply curtailed use of the summer airstrip
Wilkins runway 66° 41′ 27″ S, 111° 31′ 25″ E
http://toolserver.org/~geohack/geohack.php?pagename=Wilkins_Runway¶ms=66_41_27_S_111_31_25_E_type:airport_region:AU
you can find the runway on Google Earth with these coordinates
A polar circle is either the Arctic Circle or the Antarctic Circle. On Earth, the Arctic Circle is located at a latitude of 66° 33′ 44″ N, and the Antarctic Circle is located at a latitude of 66° 33′ 44″ S
http://en.wikipedia.org/wiki/Polar_circle
66° 33′ 44″ Antarctic Circle
66° 41′ 27″ Wilkins runway
http://en.wikipedia.org/wiki/File:Polarkreis_-_zwischen_Narvik_%26_Mo_i_Rana_Norwegen.JPG
You think someone with a brain thought of that spot to build a runway on the ice ? If the sun is warm enough in Norway to make plants grow don’t you think it is warm enough to melt the upper part of the runway on the Antarctic ? It has more or less the same coordinates.
Distance from the South pole 2500 km
Distance from open seawater in summer 50 km
Elevation AMSL 2,529 ft / 771 m
Strange maths Gary.
Let’s say power at surface on the Equator is ~1000w/m^2 and for the sake of argument that is for six hours per day (to account for Sun rising to overhead, then setting). That’s 6000wh/m^2
I’m not sure higley7 is correct about 3% but if correct, that’s 30w/m^2. (NB seems a little low to me but never mind.) That’s 720wh/m^2
One thing about the dark ocean water thing that bothers me is this…
Albedo is measured at the normal, (90° to the surface). Try driving towards the Sun in the early morning. Even dry tarmac reflects Sunlight at a low enough incidence and I don’t think anyone would argue that the albedo of tarmac is high. Once the surface is wet, the effect can be blinding.
DaveE.
You think someone with a brain thought of that spot to build a runway on the ice ? If the sun is warm enough in Norway to make plants grow don’t you think it is warm enough to melt the upper part of the runway on the Antarctic ? It has more or less the same coordinates.
You are correct that it is sunlight that is causing the melt, and not temperatures.
Reports say the airstrip near Casey Station can’t be used between December and February. Average December high temperature there is 1.4C, with most of the day below zero. Clearly melt from air temperatures will be small and quickly refreeze.
But decrease the albedo and you will get significant melt from solar radiation.
I’d say the problem here is scientists believing that rises in air temperatures are causing ice melt, and seeing air temperatures never get warm enough at that location to cause significant melt, decided there would be no problem building an ice airstrip there.
Hopefully some of those scientists have had a lightbulb moment and seen that air temperatures aren’t the primary cause of polar ice melt. Solar insolation and ice albedo are.
http://en.wikipedia.org/wiki/Casey_Station
Notice in the Antarctic picture, there is virtually no pack ice at all in the “sloshosphere”, that region between the tip of Sth America, and the Antarctic Peninsula (which is outside the Antarctic circle).
Well you would have a hard time hanging onto the land there, with the whole Pacific/Atlantic Ocean sloshing back and forth twice a day.
Antarctica’s ice is, of course, more important than the sea ice in the Arctic.
But the real issue of the Arctic sea ice is not each year’s minimum annual area.
The real issue (even though Arctic ice area is less important, anyway) is: Does the ice recover each year to a within-normal area? And it always does.
Steve Garcia
At the end of the day we are still left with the fact that we have Antarctic sea ice increasing while the Arctic sea ice is decreasing however people try to project this.All the Arctic sea ice that was lost in August has reformed in October and this seems to happen every year, it happened also in October 2007, so that we only had record ice gain in October this year because we had record ice loss in August. Just because some said the area where we have had rapid refreezing was clear of ice that was not true ,the sea ice just broke up and was transported elsewhere leaving the water still freezing cold.
http://stevengoddard.wordpress.com/2012/09/11/important-reminder-none-of-this-ice-exists/
Some people due to confirmation bias only see evidence for AGW never evidence against and if the Antarctic sea ice contridicts AGW then it has to be explained away but this years Arctic sea ice minimum was still evidence for AGW despite being caused by a strong storm in late August.
“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.”
From To Years Sq Miles Years * Sq Miles
1978 2010 32 6600 211,200
1978 2006 28 4300 120,400
——– ———–
2007 2010 4 90,800
This seems to indicate that for 2007 – 2010, total extent of sea ice surrounding Antarctica in the Southern Ocean grew by roughly 22,700 (90800/4) square
miles every year. That is about four Connecticuts or one West Virginia.
Ed of Mess from his WordPress account.
“richardscourtney says:
October 24, 2012 at 3:53 pm
Friends:
Gary Lance says at October 24, 2012 at 3:25 pm
You aren’t going to find charts drawn comparing the antarctic sea ice minimums, because there really isn’t a trend there and the minimum all depends on the weather at that time.
It is a pity that he does not know the minimum Arctic sea ice is also determined by the weather.
Richard”
It is a pity you don’t know the meaning of words and concepts and say ridiculous things.
The arctic minimum is influenced by weather and that’s why I watch the weather in the arctic daily, but if that multi-year ice is lost for any reason, it’s gone and not coming back. All sea ice is influenced by weather at all times, but influenced isn’t the same as determined. The antarctic minimum is all about how lucky the sea ice is to hide in the gyres and that is determined by the weather. The satellite record has examples of the gyres being flushed out of sea ice in the antarctic. That would lead to a record minimum for that year, but the sea ice would return and the minimum would return to the trend. The antarctic used to have sea ice left along the coast at it’s minimum and that trend is gone. If the arctic loses sea ice by unusual weather, it isn’t returning to an established minimum amount, because the trend in the arctic is for all the sea ice to melt.
In the arctic, multi-year sea ice hides along the coast of northern Greenland and the CAA, but recently the trend has been for a high pressure zone to be over Greenland and that exits sea ice out the Fram Strait and move sea ice north of Greenland towards the east. The Nares Straits opens early and exits sea ice. The CAA has started leaking sea ice through it’s many passages.
The record minimum antarctic sea ice area from satelitte data is around 1.3 million square kilometers (msk) and it was set 20 years before this melt season’s minimum which will be in 2013. The largest minimum was about 2.4 msk in 2003. In the 34 years of satellite minimum area data, there were 5 years with minimums above 2 msk and it’s usually a little less than 2 msk, but not like a flush out year, like 1993. The antarctic sea ice is free to expand in all directions around the continent and never comes close to other continents.
The arctic is an entirely different story. The arctic used to have large amounts of sea ice that would survive a melt season and now it only has small amounts of any sea ice hugging North America where conditions have changed to allow an exit to the south The record for the arctic is much more complete than the antarctic, so the change is well documented. The sea ice isn’t free to expand in the arctic, because land and warm ocean currents limit it’s expansion. The prognosis for the sea ice in the arctic is terminal and it will die much sooner than anticipated.
Gary Lance says:
“The arctic minimum is influenced by weather and that’s why I watch the weather in the arctic daily,”
Get a life.
If we compare like with like, both the Arctic and the Antarctic winter sea ice maxima are increasing. The Antarctic summer sea ice minimum is currently zero every year. If this were to change to non-zero, that would be interesting.
Gary Lance:
In response to my having pointed out that minimum Arctic sea ice is determined by the weather, at October 25, 2012 at 2:53 am, you write to me saying.
I copy the first of these quoted sentences so everybody can get the laugh at you saying that to me.
The rest of the quote is plain wrong.
The minimum IS determined by the weather. If – as this year – ice is blown out of the Arctic by winds then the minimum is low. And if the ice is not blown out of the Arctic then the minimum is high. The summer median is similar for all years because recovery rate is higher when the minimum has been low.
Richard
kadaka (KD Knoebel) says:
October 24, 2012 at 4:26 pm
Tipping points! You act like you have an interest in history, but is that interest only to serve your agenda? Do you have a concept of what the differences in time scales means? We are changing our Earth today in hundreds of years that would have taken the Earth millions of years. Species that can adapt over millions of years, can’t adapt over hundreds of years and species are a natural resource, too. Many species have given us insight about life that have directly benefited man, such as medicines. There is evidence the Earth has been through such drastic changes before and survived, right? They are called mass extinction events, so why should you care, if it happens after you aren’t around to get yours?
Just ask yourself the simple question: What changed during the period since 50 million years ago?
Around 40 Ma Australia and New Guinea separated from Antarctica and around 23 Ma South America separated and the circumpolar current was born. That isolated Antarctica allowing it to glaciate, which dropped sea levels. India had closed the gap with Eurasia around 70 Ma and CO2 was dropping quickly by 50 Ma. Greenland has had significant ice sheets as far back as around 18 Ma, but it’s varied. Modern Greenland is a product of ice ages. Around 2.5 Ma North and South America became connected and our modern thermohaline circulation began, making the Earth prone to ice ages. This also altered the remnants of a circum-equatorial current that existed for around 150 million years. Longitudinal currents behave very differently than latitudinal currents like the newly formed Gulf Stream, which now became connected with the circumpolar current.
So that 50 million years had massive changes to make the world as it is today. Essentially, 50 Ma was a different planet.
A tipping point is the concept in climate science that at some point the change becomes irreversible by it’s own momentum, based on a cause. It doesn’t mean some extreme event can never reverse the change. The arctic sea ice is beyond a tipping point and so is the change to produce exceptional weather. Cutting the emissions isn’t going to stop it now and only geoengineering including CO2 reduction could change that Humpty Dumpty world your kind has fought so hard to create and put it back together again.