It seems Antarctica once had vegetation and had a lot of rain.
This artist’s rendition created from a photograph of Antarctica shows what Antarctica possibly looked like during the middle Miocene epoch, based on pollen fossil data. Image credit: NASA/JPL-Caltech/Dr. Philip Bart, LSU › Full image and caption
PASADENA, Calif. — A new university-led study with NASA participation finds ancient Antarctica was much warmer and wetter than previously suspected. The climate was suitable to support substantial vegetation — including stunted trees — along the edges of the frozen continent.
The team of scientists involved in the study, published online June 17 in Nature Geoscience, was led by Sarah J. Feakins of the University of Southern California in Los Angeles, and included researchers from NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and Louisiana State University in Baton Rouge.
By examining plant leaf wax remnants in sediment core samples taken from beneath the Ross Ice Shelf, the research team found summer temperatures along the Antarctic coast 15 to 20 million years ago were 20 degrees Fahrenheit (11 degrees Celsius) warmer than today, with temperatures reaching as high as 45 degrees Fahrenheit (7 degrees Celsius). Precipitation levels also were found to be several times higher than today.
“The ultimate goal of the study was to better understand what the future of climate change may look like,” said Feakins, an assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “Just as history has a lot to teach us about the future, so does past climate. This record shows us how much warmer and wetter it can get around the Antarctic ice sheet as the climate system heats up. This is some of the first evidence of just how much warmer it was.”
Scientists began to suspect that high-latitude temperatures during the middle Miocene epoch were warmer than previously believed when co-author Sophie Warny, assistant professor at LSU, discovered large quantities of pollen and algae in sediment cores taken around Antarctica. Fossils of plant life in Antarctica are difficult to come by because the movement of the massive ice sheets covering the landmass grinds and scrapes away the evidence.
“Marine sediment cores are ideal to look for clues of past vegetation, as the fossils deposited are protected from ice sheet advances, but these are technically very difficult to acquire in the Antarctic and require international collaboration,” said Warny.
Tipped off by the tiny pollen samples, Feakins opted to look at the remnants of leaf wax taken from sediment cores for clues. Leaf wax acts as a record of climate change by documenting the hydrogen isotope ratios of the water the plant took up while it was alive.
“Ice cores can only go back about one million years,” Feakins said. “Sediment cores allow us to go into ‘deep time.'”
Based upon a model originally developed to analyze hydrogen isotope ratios in atmospheric water vapor data from NASA’s Aura spacecraft, co-author and JPL scientist Jung-Eun Lee created experiments to find out just how much warmer and wetter climate may have been.
“When the planet heats up, the biggest changes are seen toward the poles,” Lee said. “The southward movement of rain bands associated with a warmer climate in the high-latitude southern hemisphere made the margins of Antarctica less like a polar desert, and more like present-day Iceland.”
The peak of this Antarctic greening occurred during the middle Miocene period, between 16.4 and 15.7 million years ago. This was well after the age of the dinosaurs, which became extinct 64 million years ago. During the Miocene epoch, mostly modern-looking animals roamed Earth, such as three-toed horses, deer, camel and various species of apes. Modern humans did not appear until 200,000 years ago.
Warm conditions during the middle Miocene are thought to be associated with carbon dioxide levels of around 400 to 600 parts per million (ppm). In 2012, carbon dioxide levels have climbed to 393 ppm, the highest they’ve been in the past several million years. At the current rate of increase, atmospheric carbon dioxide levels are on track to reach middle Miocene levels by the end of this century.
High carbon dioxide levels during the middle Miocene epoch have been documented in other studies through multiple lines of evidence, including the number of microscopic pores on the surface of plant leaves and geochemical evidence from soils and marine organisms. While none of these ‘proxies’ is as reliable as the bubbles of gas trapped in ice cores, they are the best evidence available this far back in time. While scientists do not yet know precisely why carbon dioxide was at these levels during the middle Miocene, high carbon dioxide, together with the global warmth documented from many parts of the world and now also from the Antarctic region, appear to coincide during this period in Earth’s history.
###
This research was funded by the U.S. National Science Foundation with additional support from NASA. The California Institute of Technology in Pasadena manages JPL for NASA.
==============================================================
In case you are wondering (as I did) this is the orientation of the continents 20 million years ago during the Miocene period.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Bill Illis (June 18, 2012 at 6:05 pm) wrote:
“Some of the other developments such as ocean currents and continental arrangements which changed over the time period.
http://img844.imageshack.us/img844/6939/tempgeog45mlr.png “
Thanks for the reliably valuable geography notes.
In my country, the arable land is near the coast. Inland is a desert. Potentially agriculture could move inward without much fuss – assuming that the sandy soil quickly becomes nutrient rich, water sources for irrigation appear, and the indundation happens over centuries instead of decades. Otherwise it could be quite a costly relocation.
But my country is one massive island. For continents with many countries, the migration of green belts from one state to another could be disastrous for the original. As always, the point is not that the climate will change – it always has and will. it’s about the rate of change, and particularly when our heavily populated civilizations are dependent on a stable agriculture.
I think this is all about perspective. What the authors fail to point out is that CO2 was actually dropping from the Eocene (around 800 ppm or more according to GeoCarb III) through the Miocene. As well the climate wasn’t warming at this time period it was actually cooling and glaciers were advancing throughout the Miocene (according to the papers I’ve read). They just happened to look at a point in the Miocene where the glaciers had not advanced as far as they would by the end Miocene time. Also sea level curves over the period Eocene through end Miocene show a general decrease.
timetochooseagain says:
June 18, 2012 at 7:50 pm
———————————-
I have a database of CO2 estimates that I continually update as new estimates become available.
There is one series and one methodology that I have excluded, Pagani 2010 which used a new methodology that produces CO2 estimates that are much higher than the ice cores in the period they overlap so we have to assume this methodology is not accurate – I’ve excluded another methodology, paleosols or fossil soils or pedogenic carbonates, since this method has been shown to not be reliable since it depends on the time of year or season that the samples were laid down and this varies by large amounts throughout a season (0 ppm to 3000 ppm) so it is not reliable.
The sources for the CO2 data are: the Antarctic Epica DomeC ice cores, Pagani 2005, Pagani 2008, Berner GeoCarb III, Royer 2004, Royer 2006, IPCC AR4, Pearson 2000, Pearson 2009, Triparti 2009, Bao 2008, Honisch 2009, Seki 2010, Beerling and Royer 2011 and Bartoli 2011.
John Brookes says:
June 18, 2012 at 5:54 pm
But, but, but the end of this post seems to say that CO2 caused the warmth? Surely that can’t be true…
The warmer temps were “associated” with high CO2 levels. Higher res ice core records also show an association – with CO2 levels lagging behind temp changes by a few hundred years. Whatever else the author – or you – may extrapolate with regard to cause-and-effect is pure supposition with no evidence to back it up. This study certainly has no evidence for CO2 causing the warmth as opposed to vice versa. It just doesn’t have the resolution for that. You can believe what you prefer, I’ll take evidence every time.
No matter how you look at it, this casts further doubt on CO2-induced CAGW. The study suggests that CO2 levels were 400 – 600 PPM at that time; we are approaching 400 PPM and there is no sign of temperatures increasing by 10 degrees C. Except for the Antarctic Penninsula, temperatures in Antarctica are level or slightly cooling. If, as Bill Illis, suggests, CO2 levels were closer to 250 PPM, then one has to ask, what was the reason for the higher temperatures at a time when CO2 levels were much lower than today?
“Richards in Vancouver says:
June 19, 2012 at 1:58 am
It may be worth mentioning that the Drake Passage was already about 20 million years old at the time this study refers to, so I don’t think it can be a factor in the temperature variation there.”
Until the Drake Passage opened Antarctica was largely ice-free (except for mountain glaciers in the interior). After the Drake Passage opened the ice advanced all the way to the coast for the first time (the Oi-1 glaciation). During the following 20 million years the ice fluctuated, with some coastal areas being intermittently ice free, but most of the Continent wwas permanently glaciated. Then 14 million years ago the ice advanced to the coast for a last time, and has stayed there.
This is being dishonest. Far, far higher levels of co2 were unable to stop ice ages.
Co2 is more potent than previously thought!!!
Lady Life Grows says:
June 18, 2012 at 5:38 pm
None of these speculations can explain the Piri Reis map, which is known to antedate Columbus, and is more accurate on then-unexplored parts of the world than the known regions. It shows Antarctica as it would exist without ice.
========================================================================
Enough with the fairy tales. Hapgood and Menzies are pure crackpots who didn’t know the meaning of the word science or a word of Turkish. This supposed coast of Antarctica is in fact extraneous duplicated or triplicated coast of South America which Piri Reis didn’t know what to do with, so he just curved it southeastward–nobody yet knew there was actually land down there. As per the info provided by his sources, it was nice and warm along that coast. –AGF
@richard verney:
My point exactly! Sea levels could rise a hundred meters or more, and as long as it didn’t happen overnight, there is NOTHING to be concerned about. Okay, if you own some ocean-front property (or any land within a few miles of the coast, or anywhere in Florida or Louisiana, then you’re going to lose that land. But we’re not talking about the effect on individual landowners; we’re talking about the effect on the world population of humans. total land area will decrease, by perhaps ten to twenty thousand square miles worldwide. But LIVABLE land area will INCREASE by much more than that. Hundreds of thousands of square miles of land, currently too cold to support human habitation, will be opened up for settlement. Vast stretches of Siberia and Canada. The interiors of Greenland, Iceland, and Scandinavia. The Hudson Bay will become the new Club Med.
Of course, a hundred meters is not what we’re talking about. That would take thousands of years (the worst predictions, well worst REALISTIC predictions, of sea level rise are around 2 feet per century). It would take longer than all of recorded human history for sea levels to rise a hundred meters, even if global warming continues unabated. And sometime during that period, the glacial/interglacial cycle is going to turn south again, driving the climate back into the depths of the current ice age, and nullify any temperature gains (and land loss) due to AGW.
Unless, of course, we can do something to stop the natural climate cycle of the planet. It is my most fervent wish, for the future of humanity, that the global warming alarmists are RIGHT, and that we really CAN control the earth’s temperature, to a significant degree, through anthropogenic emissions of greenhouse gasses. Because if we can’t, then about 10,000 years from now, the human race is REALLY going to be in trouble. Not the kind of pissant trouble the alarmists think we’re in now, but REAL trouble. And your great (x300) grandchildren will be fighting for survival against bitterly cold temperatures, complete lack of agricultural production, and global wars fought over the few remaining resources. Personally, I don’t think we can do anything to avoid it, no matter how much fossil fuels we burn. But if we don’t at least TRY to stave off the coming glacial period, then we will be condemned by 3,000 generations (100,000 years – that’s how long the glacial period will last) of future humanity.
That’s not exactly surprising. Because of the circumpolar winds and currents, Antarctica is relatively thermally isolated from the rest of the planet, plus you have the thermal inertia of the ice sheet itself. More than one study has predicted a slower start for warming to affect the Antarctic region.
But the time scales involved are quite different. I haven’t seen a copy of the study (paywalled) but it appears it is speaking of resolution no finer than thousands of years – not decades. But lets look at the figures: 10C increase in summertime temps in the Antarctic. That may have taken thousands of years with a slow rise of CO2 (playing DA on behalf of the mainstream view). Now lets look at the Arctic. Annual temps there have increased by nearly 1.5C over 3 decades. A straight extraolation makes that almost 5C over 100 years, and if CO2 continues to rise to 600ppm by 2200, then the rise could be as much as 10C over 200 years. Presumable Antarctica will have started to warm in that time.
Or at least, that would be the mainstream view.
But there are other differences regarding tectonic arangement and ocean circulation and heat transport, so it’s not a straight apples to apples comparison in the first place. The study I linked above examines a number of other factors that may account for the seemingly greater warmth 15-20 million years ago.
This study neither proves nor disproves AGW, nor does it put a constraint on climate sensitivity. It does add to knowledge, and there is no need for over-interpretation of the, quite qualified, findings.
And a decent climate skeptic should keep in mind that this study relies on ancient proxies and modeling. Normally this would render the paper extremely suspect. but I personally hope that, rather than overlooking these traditionaly suspect elements because there is some grist to the skeptic mill, skeptics have instead decided that proxies models can be useful, if not perfect.
ian middleton says:
June 18, 2012 at 6:38 pm
I seem to remember that Captain Scott found coal down there on his last expedition.
That has nothing to do with the Miocene. That coal could well have been from an outcrop of the Carboneferous a period when Antarctica was part of Gondwana.
Vertical coastal displacement per unit of time, in approximate order (if you don’t like it make your own list):
1) Due to tsunamis
2) Due to hurricanes and other low pressure systems
3) Due to landfill accumulation
4) Due to oil depletion
5) Due to groundwater depletion or repletion
6) Due to GIA
7) Due to tecktonic movement
8) Due to dust accumulation (in mountainous areas) or silt near sea level
9) Due to variable sea volume
Tells are the remains of ancient cities, many of which began on the plain, and they have risen faster than the sea has. And primitive garbage did not compare at all with ours. –AGF
… “thought to be associated with CO2 at 400 to 600 ppm …”
According to this study for the Middle Miocene (16-15 million years ago)
Another recent study: http://www.eurekalert.org/pub_releases/2012-06/sfsu-stl060612.php
“Around 5 to 13 million years ago, oceans were warmer than they are today — even though atmospheric carbon dioxide concentrations were considerably lower.”
“CO2 concentrations for the period were only 200-350 parts per million”
“that late Miocene sea surface temperatures were significantly warmer than today across a large swath of the North Pacific”
To George at 10:27 am:
Yes, the late Miocene was warmer, considerably, than today, with lower CO2 levels. What could have created such a warmer world, if CO2 wasn’t the culprit (which obviously it wasn’t)?
The link you provide ends with this sentence:
“One major waterway that began to close during the period was the Central American Seaway, an ancient body of water separating North and South America. The seaway was later closed by the volcanic creation of the Panama isthmus.”
This is the point I was making in my 7:20 PM comment above, that ocean circulation patterns changed because of the closing of the isthmus which connected the Atlantic and Pacific somewhere around 3 to 3.5 million years ago, and the change in patterns eventually resulted in a cooler world, with little change in CO2 levels. So you can’t take the mid-Miocene, with up to 600 ppm of CO2 and much warmer than today, as a model for what would happen if today’s much cooler (baseline) world went to 600 ppm.
Again, in response to a previous comment, it is certainly possible that sea level rise could be a major problem, for example if it were to rise 10 feet. I’d like to see the costs of losing that much coastline, that much farm land, and having to enclose that many coastal cities to prevent constant flooding. But I am NOT saying that 600 ppm or 900 ppm would create sea level rise like that, we need to get the science right before we can say something like that. For starters, it depends on whether we would stay at such levels for hundreds of years – it isn’t just the level of CO2, but for how long.
“’This is some of the first evidence of just how much warmer it was.”
Dude, we already knew that. (Look up the work of Haq, Berggren, Bartek, Vail, Al-Fares, Al-Qahtani, and a dozen others for starters.'”
Thanks for that PF.
Also, Lady Life Grows, about the Piri Reis map.
“In 2012, carbon dioxide levels have climbed to 393 ppm, the highest they’ve been in the past several million years. ”
How about 450 ppm in 1940. Why are direct chemical bottle CO2 measurements almost totally ignored by people just because the warmists prefer to ignore them? Some 80,000 measurements by many different researchers—EE Beck’s Paper.
For number of years geology professors have been teaching about the warm Antarctic during the early Tertiary, so this is hardly news. We have known for some time that there were herbiverous dinosaurs there in the Cretaceous. Miriam Katz has written extensively on the development of the Antarctic Circum Polar Current in late Eocene or Early Miocene time, a development which stopped the warm Pacific waters from reaching Antarctica and warming its climate. From such effects it is easy to see that ocean circulation, which is obviously greatly influenced by plate tectonics, is the main driver in long-term global warming and cooling.
Refer also to the rise of the Isthmus of Panama, and its effect on the Pacific Current warming the North Atlantic (current work by the U. of Florida, et. al. One author said that this rise, cutting off the warming effect of that current, “created the Arctic”. There is much to be said for tht argument, since there seems to have been little or no Arctic prior to the rise of the Isthmus in the Miocene.
Ocean currents and plate tectonics don’t leave much room for anthropogenic global warming.
George, CPG