Study: The Late Cretaceous Period was likely ice-free


From the University of Missouri-Columbia

COLUMBIA, Mo. – For years, scientists have thought that a continental ice sheet formed during the Late Cretaceous Period more than 90 million years ago when the climate was much warmer than it is today. Now, a University of Missouri researcher has found evidence suggesting that no ice sheet formed at this time. This finding could help environmentalists and scientists predict what the earth’s climate will be as carbon dioxide levels continue to rise.

“Currently, carbon dioxide levels are just above 400 parts per million (ppm), up approximately 120 ppm in the last 150 years and rising about 2 ppm each year,” said Ken MacLeod, a professor of geological sciences at MU. “In our study, we found that during the Late Cretaceous Period, when carbon dioxide levels were around 1,000 ppm, there were no continental ice sheets on earth. So, if carbon dioxide levels continue to rise, the earth will be ice-free once the climate comes into balance with the higher levels.”

In his study, MacLeod analyzed the fossilized shells of 90 million-year-old planktic and benthic foraminifera, single-celled organisms about the size of a grain of salt. Measuring the ratios of different isotopes of oxygen and carbon in the fossils gives scientists information about past temperatures and other environmental conditions. The fossils, which were found in Tanzania, showed no evidence of cooling or changes in local water chemistry that would have been expected if a glacial event had occurred during that time period.

IMAGE: In the study, MacLeod examined fossils of organisms that lived 90 million years ago. This photo is an image from a Scanning electron microscope of a planktic (left) and benthic…Click here for more information.

“We know that the carbon dioxide (CO2) levels are rising currently and are at the highest they have been in millions of years. We have records of how conditions have changed as CO2 levels have risen from 280 to 400 ppm, but I believe it also is important to know what could happen when those levels reach 600 to 1000 ppm,” MacLeod said. “At the rate that carbon dioxide levels are rising, we will reach 600 ppm around the end of this century. At that level of CO2, will ice sheets on Greenland and Antarctica be stable? If not, how will their melting affect the planet?”

Previously, many scientists have thought that doubling CO2 levels would cause earth’s temperature to increase as much as 3 degrees Celsius, or approximately 6 degrees Fahrenheit. However, the temperatures MacLeod believes existed in Tanzania 90 million years ago are more consistent with predictions that a doubling of CO2 levels would cause the earth’s temperature could rise an average of 6 degrees Celsius, or approximately 11 degrees Fahrenheit.

“While studying the past can help us predict the future, other challenges with modern warming still exist,” MacLeod said. “The Late Cretaceous climate was very warm, but the earth adjusted as changes occurred over millions of years. We’re seeing the same size changes, but they are happening over a couple of hundred years, maybe 10,000 times faster. How that affects the equation is a big and difficult question.”

MacLeod’s study was published in the October issue of the journal Geology.


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CO2 levels of 1000 ppm will melt all the ice? Even if you believe in the “greenhouse gas” effect of CO2, the logrithmic nature of it will mean it has no effect from about 300 ppm onwards.
Obviously that sort of detail seems to be too technical for the authors.

“In our study, we found that during the Late Cretaceous Period, when carbon dioxide levels were around 1,000 ppm, there were no continental ice sheets on earth. So, if carbon dioxide levels continue to rise, the earth will be ice-free once the climate comes into balance with the higher levels.”

One heck of an assumption – that CO2 levels are the cause of an ice-free earth! Where is the evidence to support such a quantum leap – what is the cause and effect – does CO2 drive temperature or temperature drive CO2 – or is some other mechanism at play

Pete Brown

This is because CO2 is the only thing that controls climate. Therefore whatever conditions were like 90 million years ago is solely the result of the CO2 levels that existed at that time. So if CO2 returns to the levels that existed 90 million years ago, the climate will be exactly as it was 90 million years ago.
The continents will presumably realign themselves to where they were 90 million years ago as well.
This will happen 10,000 times faster than it did in geological times gone by because of human emissions, and that’s obviously why he’s worried. You can imagine the mayhem with the continents all moving about so quickly.
Powerful stuff this CO2. Makes perfect sense when you think about it.
(For those in any doubt, I am being sarcastic)


If there was no ice in Antarctica, well, that means that once the ice is gone we will likely be able to extract lots of oil from there!
Now seriously, no matter how fast we put CO2 into the atmosphere, even if the long-term status with that ammount of CO2 was an ice-free planet (which nobody has proved), it would take many thousand years to melt all that ice. Before that has any chance to happen, Milankovich cycles will bring back the ice.


Rubbish.Start with a CAGW meme and fit the paper around an already agreed conclusion. A simple Google for ice sheets in Late Cretaceous destroys this paper.e.g.
“Milankovitch forced cyclic alternations from drier to wetter climatic periods caused vegetation variability from 72 to 77Ma. This climate change was probably related
to the waxing and waning of ephemeral (100 ky) small ice sheets in Antarctica during times of insolation minima and maxima. Drying and cooling after 72 Ma culminated from 68 to 66 Ma, mirroring trends in global δ 18 O data” – Gallagher et al, Science Direct, 2008.

Mike McMillan

Unlike the MWP in Greenland, which was a local thing, if Tanzania didn’t have glaciers, I guess the whole world didn’t. But then again, that was before Tanganyika and Zanzibar merged, which I doubt was taken into account in the study.
CO2 driving temperature again.

Pete Brown

It’s not all bad. Intercontinental flights will be cheaper.


We are probably dealing with the biggest scientific fraud in History since this paper: 1981_Hansen_etal.pdf (published in ‘Science’)
Para 2; the claim that CO2 blocks IR in the range 7-14 microns (two small bands at ~ 10 microns) is wrong. The correct 15 micron band would only cause 1.2 K surface temperature increase for no change of OLR spectral distribution as [CO2] varies; untrue.
Para 4; the 33 K ghe claim fails to account for the loss of cloud and ice albedo if ghgs were taken from the atmosphere, giving 43% SW energy increase: real ghe ~ 11K; 3x positive feedback wrong from the start.
This passed peer review hence this IPCC mantra is shown up to be ‘Believe us because we conned you in the past.’. In reality CO2 climate sensitivity is probably <0.1 K.


[snip -inappropriate – mod]

Robin Hewitt

Good heavens, I just followed a link to here from

Where are the “p” values, and what was the confidence interval? Certainly, there are some numbers associated with this “study”, or is it just another press release in the run-up to AR5?


During the late Ordovician temperatures were much lower and CO2 ppm over ten times higher than today.

Kon Dealer

“Late Cretaceous Period was likely ice-free….At the rate that carbon dioxide levels are rising, we will reach 600 ppm around the end of this century. At that level of CO2, will ice sheets on Greenland and Antarctica be stable?” Yada yada, CO2 waffle CO2.
What about the position of the continents, Numbskull? Antarctica is not isolated, no cirumpolar vortex etc, etc. How can you make direct comparison? You can’t. It’s hand-waving.

Greg Goodman

“This finding could help environmentalists and scientists predict what the earth’s climate will be as carbon dioxide levels continue to rise.”
Indeed, for a start it shows that there is not run-away climate change/tipping point/climate catastrophe with the “ocean boiling way” al a Hansen.
Climate is stable a 1000ppmv CO2 and at much higher temps. As stable as it is now.


Robin Hewitt said, 1:42am
“Good heavens, I just followed a link to here from“.
Now that does it for me, I can believe most things within the climate debate but this is ridiculous. A link from the BBC to WUWT, I suggest more water with whatever you’re drinking Rob. 😉

old construction worker

And we tax payers pay them to produce this “study”.

Greg Goodman

“So, if carbon dioxide levels continue to rise, the earth will be ice-free once the climate comes into balance with the higher levels.”
Spurious and false assumption that temperature stabilises to match CO2 when the climate record clearly shows it is the opposite.
When “the climate comes into balance” it will have reabsorbed the excess CO2 to the level determined by temperature.
That day is a long way off and we almost certainly will not be here to worry and tweet about it. Real problems will likely intervene in the future of society long before then.

Peter Dunford

I thought I’d read that the ice caps only formed after North and South America joined up and stopped the warm Pacific water flowing into the Atlantic. 1000 ppm of CO2 didn’t cause that.

Yes we had an ice age in the Ordovician period, with very high levels of CO2

Greg Goodman

AleaJactaEst says:
Rubbish.Start with a CAGW meme and fit the paper around an already agreed conclusion. A simple Google for ice sheets in Late Cretaceous destroys this paper.e.g.
In what way does the fact you get a match for certain keywords on Google “destroy” the paper.
Sceptical science requires thought not stupidity. Try again.

It’s a conspiracy to drive sand bag prices to an all-time high.


Hand to face in despair… so we are back to 6 degrees now? These people just will not give up. Just when we thought that some sanity was starting to take hold. I can hardly bear to read this kind of simplistic reasoning any longer. This CO2 meme rivals the survival capacity of a cockroach. It just will not DIE! (Great little creatures, no?)


Greg Goodman
The criticism is quite well placed. They can only draw their conclusions (linking CO2 to global ice) by assuming that CO2 is the only thing, whether directly or indirectly, that drives climate. They make an assumption to support a hypothesis. Is this really good science or just the same old trite dressed up as new research.


Actually there are strong indications that there were fair-sized icecaps inland in Antarctica at least intermittently during the Cretaceous. The main reason to believe this is that there were many (geologically) abrupt changes in sea level on the order of tens of meters which are difficult to explain except through the formation and melting of reasonably large icecaps. They were probably never large enough to reach the coast though.
Unfortunately the interior parts of Antarctica aren’t easily available for research, but there is very strong evidence for a cool temperate climate with winter temperatures well below freezing from Southern Australia.
That the water temperature in Tanzania wasn’t affected by inland icecaps in Antarctica isn’t exactly startling – it wasn’t much affected even by the recent worldwide glaciations. As for “water chemistry” I suppose he means oxygen isotope ratios, since the chemistry of tropical oceans would not be affected by glaciations in Antarctica in any case. It is also doubtful how well ice in Antarctica would show up in isotope ratios in the tropical Tethys, there wasn’t any cold Antarctic Deep Water in the oceans then, and if the ice-volume didn’t change markedly during the studied interval there would be no signal at all in tropical foraminifera. Unfortunately there is no information on how long the studied interval was, or its exact stratigraphic position so it’s impossible to correlate it with the sea-level curve.


This finding could help environmentalists and scientists predict what the earth’s climate will be as carbon dioxide levels continue to rise.

Can it? I only ask because the continents’ positions look very different today as well as ocean circulations. And the Isthmus of Panama which formed 3 million years ago also changed the climate patterns which also helped form the Arctic? Then there is Antarctica. During the late Ordovician ice age co2 was over 10 times higher than today.
Can someone more knowledgeable than me explain how this study helps “environmentalists and scientists predict what the earth’s climate will be as carbon dioxide levels continue to rise”?


It’s called a rearguard action, and it isn’t working anymore. They’ve obviously joined the parade late or have lost touch with what is currently happening in the field of climate “science”.


Yeah Jimbo, you make an excellent point. As a geologist they should have started from the point of continental positioning.


It must have been all those dinosaur farts warming the atmosphere in the Late Cretaceous. Maybe that is why the dinosaurs went extinct, breathing in too much of their own gases.

Mickey Reno

Good God, do these people ever listen to themselves? Do they not understand where the Anarctic continent is located? How the ice has formed in spite of very little atmospheric moisture penetrating into the interior?
What will be the freezing/melting seasons in Antarctica when and if CO2 ever reaches 800 or 1000 ppm? Will the low winter temps be minus 85 degrees instead of minus 90? The average annual temp of the Antarctic interior is about -50C. How much ice is going to melt if the average annual temperature rises to -45C? How do we rule out that if it warms by a little bit, more precipitation might penetrate the interior, and that more snow would fall, actually increasing the ice sheet mass and lowering sea levels? I’m sorry, but I just have to call Balder Shot on this kind of idiocy.


Here is an interesting quote from Miller et al (2003):
“The alternative to invoking Late Cretaceous ice sheets is that global sea-level changes were paced by as yet undefined mechanisms, because none of the other hypothesized mechanisms (temperature effects, storages in lakes, deep-water changes, groundwater, or sea ice) can explain the observed 20-30 m changes in <1 m.y. Thus, because our data require that large, rapid sea-level variations occurred in the Late Cretaceous greenhouse world, we must conclude that either moderate-sized ice sheets paced sea-level changes during this time, or that our understanding of causal mechanisms for global sea-level change is fundamentally flawed."


1000 ppm !? good grief..the oceans would have been seething cauldrons of acid…no wonder there was no ice !

Pete Brown

[done . . mod]


What about circumpolar currents?
The map shows Antarctica linked with Australia. As every student knows – when Australia began its long march north, the sea channel opened up to isolate Antarctica and prevented warm water from the north getting to it. Cold water circulated round Antarctica and it then began to freeze over.
CO2 has nothing to do with it.

David L.

600ppm to go, at 2ppm per year, equals 300 years to being ice free.

Silver Ralph

Derrr – I would have thought the fact that the Ruskies are drilling for oil in the Arctic (as well as BP’s northern Alaskan fields), would be a good indicator that the Arctic was ice free during the Cretaceous period. Do we really need any more evidence?
(And I see that the continental-drift position of the Arctic was about the same then, as it is now).
And where did that leap of faith come from, about this ice-free north being due to CO2? Who says? Where is the evidence? Is science now a matter of pontificating, rather than evidence? Are they going to change the name for Scientific Papers into Scientific Bulls?
What about solar activity, orbital eccentricity, or even ocean circulation patterns as the continents began to divide?? Does nobody in science use rational thought any more?

Take Off Your Shoes & Feel the Global Warming

Mickey Reno:
Didn’t you know that beneath the Antarctic is where the unfindable deep ocean global warming heat is stored. That alone is going to turn the continent into molten lava. 🙂

Crispin in Waterloo but really in Jakarta

OMG 10,000 times faster! It will be almost as fast as a Younger Dryas Event! How will life survive!

Peter Jones

If the CO2 did all of that, then it is hard to imagine how we managed a 17 year plateau with steadily increasing CO2. The rate is supposed to be 10,000 X faster!! So a late Cretaceous plateau would be ~150,000 years I guess.

John S.

Robbin Hewitt wrote: “Good heavens, I just followed a link to here from
Was it from this article?:


“David L. says:
September 26, 2013 at 2:58 am”
If we consider that ~50% of emissions of CO2 from human activities is absorbed, to get to 1000ppm would take ~600 years. What? Me worry?


“John S. says:
September 26, 2013 at 3:15 am”
You are right! I am totally surprised to see WUWT linked in an article at Anthony, what have you done? You will have the entire BBC reading latte/chardonnay set crying into their drinks!

Fred Souder

It is amazing that a Geologist would have this opinion. The geology department at KU just down the road is openly scornful of the idea of a CO2 governed paleo climate. What is going on at MU?

Great Greyhounds

I was really hoping that they had ‘modeled’ the ocean currents to backup their claims, but no! Sometimes those models would get in there way of their Religion…

Dodgy Geezer

Is this why we don’t have any Late Cretacean Polar Bears any more?
Won’t somebody think of the poor little cuddly animals? BAN tectonic movements NOW!!!!

James Schrumpf

How does the author figure CO2 got so high without human intervention? There is no known natural cycle that increases CO2 and then decreases it again. There are lots of known natural cycles that increase and decrease temperature. Sans human beings, what is the proposed mechanism that creates the Ordovician and Cretaceous CO2 rise, and then fall?


And my point is . . . .
(Sigh) Let’s remind ourselves . . . .
Fact: Excluding CO2, 99.96% of ‘the sky’ is made up of all the other atmospheric gases. This leaves CO2 at just 0.040% (400 parts per million). For those decision makers who have still not grasped how miniscule this amount is and prefer it explained in simple terms, think of 1 x Imperial Gallon of CO2 to every 3,200 gallons of air (0.040% of 3,200 = about 1).
Fact: There are two types of CO2 – ‘naturally occuring’ and ‘man-made’. 96.775% of CO2 is naturally occurring, thus leaving man-made CO2 @ 3.225%. For those decision makers who still have not grasped how miniscule this amount is and prefer it explained in simple terms, there are 8 pints in 1 x Imperial Gallon. Of the gallon of CO2, 7.75 pints of it is completely natural and 0.25 pints is man-made (96.775% of 8 pints = 7.75 pints).
Are you still with me? Good.
Fact: For every 3,200 gallons of air, 7.75 pints of CO2 is naturally produced by: All plant photosynthesis, Respiration in all animal life, Volcanic eruptions, Geysers, Natural ‘wildfires’, Marine life Respiration (incl. Corals), Micro-organism respiration, Anearobic digestion (plant decay), Cellular respiration, Food digestion waste (flatulence), Natural animal decomposition (Decay), Calcification (Stalactites & Stalagmites) and Natural fermentation (yeast moulds).
Fact: For every 3,200 gallons of air, JUST 0.25 pints (5 Fl.oz.) is produced by humans. This includes: Burning of any fossil fuel (oil, oil derivatives, coal, natural gas, peat and wood alcohols); Burning of timber or crops (wood burners, domestic fires, wood chips in bio-mass, charcoal, human caused forest fires, garden incinerators); Global alcoholic beverage market (brewing industry, wine & champagne production, beer dispensing propellant, distillation); Carbonated drinks & beverage industry (man-made CO2 injected into soft drinks as a novelty effect – adding no flavour whatsoever); Decaffinated coffee manufacture; Food Manufacture (the world’s entire daily bread production, sodium bicarbonate aeration in snackfoods/biscuits/crackers/cakes/sponges, yeast extract, modified air packaging to prevent oxidising, dry ice used to keep fruit & vegetables fresh); Refridgeration (fridges, freezers, air-conditioning); Industrial Processes (coolant gas in welding & fabrication, lime kiln processes, industrial waste incineration, sand-blasting using highly pressurised pellets of frozen CO2, laser cutting of all PCB’s for electronics/TV’s/computers); Propellants (fire extinguishers, air bags, life vests, aviation ‘exit slides’); Stage, film & theatre (dry ice, CO2 cannons); Water purification; Limescale removal products; Denture cleaning products; . . . . and finally, anything humans throw out for Composting (garden waste, peelings, etc.).
And my point is . . . . how can such a minuscule amount of man-made gas be responsible for a 1 degree C temperature increase in the last century – and that our decision makers feel that by curbing just the ‘burning of fossil fuels’ part of this minuscule amount of man-made gas (ignoring all the other ways we manufacture the stuff) that they will save the world from doom – however much it costs.


PS Forgot to include Andrews Liver Salts.
Are there any other ways we are ‘accountable’ for the impending doom? Jeez.

At 1000 ppm CO2 doesn’t all life except cockroaches end? So what happened here? Shells sll dissolved in the acidic oceans. All the limestone dissolves. Now to just fivutr out wherr the CO2 came from.


‘Some of the oldest buried ice deposits in Antarctica are reportedly up to 8.1-million-years old (Sugden et al., 1995).’


“GeeJam says:
September 26, 2013 at 4:07 am”
Great post. One of the simplest analogies, and visuals, I have seen described uses graph paper. Graph paper 1mx1m with 1mm squares. That’s 1 million squares. Colour in a square that is 20mmX20mm, that’s 400 squares. Now colour in a square that is 2mmx2mm, that’s 4 squares. Divide that by 2, that’s the annual human contribution to CO2 concentration.