Imperial College London
Researchers have found evidence of rainforests near the South Pole 90 million years ago, suggesting the climate was exceptionally warm at the time.
A team from the UK and Germany discovered forest soil from the Cretaceous period within 900 km of the South Pole. Their analysis of the preserved roots, pollen and spores shows that the world at that time was a lot warmer than previously thought.
The discovery and analysis were carried out by an international team of researchers led by geoscientists from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Germany and including Imperial College London researchers. Their findings are published today in Nature.
Co-author Professor Tina van de Flierdt, from the Department of Earth Science & Engineering at Imperial, said: “The preservation of this 90-million-year-old forest is exceptional, but even more surprising is the world it reveals. Even during months of darkness, swampy temperate rainforests were able to grow close to the South Pole, revealing an even warmer climate than we expected.”
The work also suggests that the carbon dioxide (CO2) levels in the atmosphere were higher than expected during the mid-Cretaceous period, 115-80 million years ago, challenging climate models of the period.
The mid-Cretaceous was the heyday of the dinosaurs but was also the warmest period in the past 140 million years, with temperatures in the tropics as high as 35 degrees Celsius and sea level 170 metres higher than today.
However, little was known about the environment south of the Antarctic Circle at this time. Now, researchers have discovered evidence of a temperate rainforest in the region, such as would be found in New Zealand today. This was despite a four-month polar night, meaning for a third of every year there was no life-giving sunlight at all.
The presence of the forest suggests average temperatures were around 12 degrees Celsius and that there was unlikely to be an ice cap at the South Pole at the time.
The evidence for the Antarctic forest comes from a core of sediment drilled into the seabed near the Pine Island and Thwaites glaciers in West Antarctica. One section of the core, that would have originally been deposited on land, caught the researchers’ attention with its strange colour.
The team CT-scanned the section of the core and discovered a dense network of fossil roots, which was so well preserved that they could make out individual cell structures. The sample also contained countless traces of pollen and spores from plants, including the first remnants of flowering plants ever found at these high Antarctic latitudes.
To reconstruct the environment of this preserved forest, the team assessed the climatic conditions under which the plants’ modern descendants live, as well as analysing temperature and precipitation indicators within the sample.
They found that the annual mean air temperature was around 12 degrees Celsius; roughly two degrees warmer than the mean temperature in Germany today. Average summer temperatures were around 19 degrees Celsius; water temperatures in the rivers and swamps reached up to 20 degrees; and the amount and intensity of rainfall in West Antarctica were similar to those in today’s Wales.
To get these conditions, the researchers conclude that 90 million years ago the Antarctic continent was covered with dense vegetation, there were no land-ice masses on the scale of an ice sheet in the South Pole region, and the carbon dioxide concentration in the atmosphere was far higher than previously assumed for the Cretaceous.
Lead author Dr Johann Klages, from the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, said: “Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm. But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in the Antarctic.”
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If you go to http://www.scotese.com, you can view Chris’s spectacular animated recreations of plate migrations over the last 540 million years.
It appears the chunk that became (east) Antarctica drifted between 40S and 60S during mid-Cretaceous 120-80 Mya, so good place to grow rainforest
I just roll my eyes whenever anyone infers temperature based on estimated CO2 – that is just sooooo backward.
GeologyJim,
Worse than that. They infer CO2 levels from inferred temperature and climate models that no doubt are tuned to an ECS of 4.5 or higher.
EurekAlert!, defenders of the faith.
If we were to resurrect these tree species today, they could well require a hothouse pumped full of CO2 to survive. Current atmospheric levels are historically low rather than hysterically high.
How could such an ecosystem exist with darkness 24/7 many months each year? Never have I understood that. Ellesmere Island in Northern Canada has the same problem. Light is the problem, more than temperature.
The warmth of Antarctica millions of years ago was not only from global temperature being warmer, but also because Antarctica was in a part of the world that’s warmer than the South Pole. And its warmer location was a contributing factor to the global warmth back then: That made it and its surrounding waters free of snow and ice, or at least free of sea ice and year-round land cover of ice or snow. That means lower albedo and contributes to a warmer world. And without the thick ice sheet that it has now, parts of Central America were under water and that favored more global circulation of ocean water, which would make the temperature of the world more even and the poles warmer. Also, the Bering Strait was wider (due to continental drift) and with deeper water due to higher sea level, and that also favored the Arctic being warmer and the world being warmer.
I worked on a project in the late 90s looking at plant growth at different latitudes. We found that the net primary productivity was based upon sunshine (light flux) and basic growing conditions, ie temperature, moisture, and nutrients.
The conclusion and the experimental evidence showed that the plants at high latitude grew the same amount, but in a shorter amount of time. For some plants, the lack of a transition to a hot summer, meant they produced more.
One of the questions that we never answered, which is something I have yet to see, is a way to estimate solar flux if the other quantities are fixed.
CO2 and temperature decoupling at the million-year scale during the Cretaceous Greenhouse – https://www.nature.com/articles/s41598-017-08234-0
So warm enough to have a deciduous forest was for completely different reasons. There was very little difference in sea surface temperatures with latitude then, compared with today, because ocean currents flowed NS. You don’t need to be an expert in climate science to know this, so this story highlights how much of a climate tart you need to be to have a successful career in science instead of being good at science.
These currents make a huge difference even today.
Quick quiz. Which has the lower coldest temperature on record? Tromso, Norway (300 km inside the Arctic circle) or Tallahassee, Florida?
The capital of FL, of course. The North Atlantic Drift is a warm Mama.
Another factor which GCMs can’t model is Cretaceous equanimity, ie the relative lack of difference between equator and poles. Earth’s tilt range was probably the same then as now, so the evenness of temperature must be down to oceanic and atmospheric circulation, plus just generally a lot warmer.
CO2 was an effect of this balminess and evenness, not its cause.
They are only a hundred years or so a bit late to “discover” evidence of rainforests . Scott on his race to be first to the pole found and retrieved petrified wood in that trip, before WWI
Quote: “Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm. But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in the Antarctic.”
They have a lot of confidence that models that cannot predict next years climate will work on scenarios from 90 million years ago.
Why the surprise of finding Jurassic coal in Antarctica? Not having seen the paper, how this was presented is unclear. However much older coal was found far back in 1907-09. It is easy to find a 36-year-old map on the web showing locations of coal in the Antarctica from the Tertiary, Triassic to as old as the Permian. All coal will show traces of plant material, so nothing new. The Australian CSIRO Division of Coal Research back in the 1960s did analysis and testing of some Antarctica Permian coal samples, in which I participated.
Also see here:
http://www.antarctica.gov.au/about-antarctica/environment/geology/mining
Would like to share my post on the Antarctica rainforest
https://tambonthongchai.com/2020/04/03/antarctica-rainforest/
Time waits for no one and no thing. Climate and the Earth are living Systems. Over Billions of year’s on the Earth’s timescale, the Climate and Earth have never been Constant, they will change with all the variables, they will never be static. If the Climate and the Earth ever does become constant, unchanging, flat-lined, that will be when the Earth and Climate are dead. So you have to question any movement who’s Agenda is to STOP Climate Change. Our goal should always be #optimization, #innovation, #reality for #capableenergy, not #subsidies for #incapableenergy. we must question #justintrudeau #left #un #ipcc #climatemodels as to where their plan is really going.
Weather and Climate have many more records than those just witnessed over the past 100years. We have been Warmer, Cooler, Wetter, Drier, Windier throughout time, but NEVER have we been this gullible to think that a regulated, ever-improving society will implode in 10 years! Yes we must do our best, but we must base all Policies on Reality, to the best of our current capabilities, rather than try to fit with Failed Climate Models and Socialist Agendas.
Before we start talking about rainforests at the South Pole, we need to remember that the continents wander over millions of years. Where was Antarctica 90 million years ago? Geologic evidence indicates that 90 million years ago, Antarctica was moving south towards the south pole. Was it at the South Pole at that time, or was it more likely at the current latitude of New Zealand, where there are currently rain forests?
The paper claims the site was at 82 degrees S, but it might have been farther north, while still within the Antarctic Circle, far south of NZ.
Please state whatever point you’re trying to make.
It’s clear from all evidence that climate was much warmer during the Cretaceous. We observe tectonics working today, so that the plates moved in the past is indeed consistent with uniformitarianism.
Always go straight to the abstract. It says the most important information, that the excavated forests were at latitude 82, far enough north to be at a present day Antarctic coast.
Article, Published: 01 April 2020
Temperate rainforests near the South Pole during peak Cretaceous warmth
Johann P. Klages, Ulrich Salzmann, […]
Nature
volume
580,
pages
81–86(2020)
Abstract
The mid-Cretaceous period was one of the warmest intervals of the past 140 million years1,2,3,4,5, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume6. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide.
That’s interesting. It’s almost as if the ground has shifted thousands of miles. For example, the Grand Canyon has clearly been under the ocean, three times already. That’s a big move, I wonder how long it takes.