Changes in the Earth’s climate over the last 66 million years have been revealed in unprecedented detail by a team involving UCL researchers, highlighting four distinctive climatic states and the natural million- and thousand-year variability that Earth’s climate has experienced.
Published this month in Science, the new global “climate reference curve” created by the team is the first record to continually and accurately trace how the Earth’s climate has changed since the great extinction of the dinosaurs 66 million years ago.
It was achieved by bringing together research from 12 international laboratories using sample material from the ocean floor collected over more than five decades of international scientific drilling expeditions by the International Ocean Discovery Program (IODP) and its predecessors.
Led by researchers from MARUM — Center for Marine Environmental Sciences at the University of Bremen, the Potsdam Institute for Climate Impact Research (PIK) and UCL, the authors used advanced mathematical analysis of this highly accurate climate reference curve to identify four climatic states, classified as “Hothouse,” “Warmhouse,” “Coolhouse,” and “Icehouse.” These states are recognized by the characteristic pattern of their climate variability. The distinctive climatic “beat’ of each state is driven by greenhouse gas concentrations and polar ice volume, with higher CO2 and little-to-no global ice volume during the Hothouse and Warmhouse compared to the Coolhouse and Icehouse.
To generate the climate reference curve, called CENOGRID (CENOzoic Global Reference benthic foraminifer carbon and oxygen Isotope Dataset), the team analyzed and compiled the oxygen and carbon isotopes from tiny microfossils found in deep-sea sediments. For the first time, this period of Earth’s history was accurately dated by identifying the imprint of semi-periodical changes in Earth’s orbit around the sun in CENOGRID.
The CENOGRID is the clearest and most accurate view of past climate conditions to date, providing information about past deep-sea temperatures, global ice volumes, and the carbon cycle. These detailed climatic changes can be studied like a colorful barcode and used to draw comparisons between the past, present, and future.
Co-author Dr. Anna Joy Drury (UCL Earth Sciences), said: “We use CENOGRID to understand what Earth’s normal range of natural climate change and variability is and how quickly Earth recovered from past events. While we show that the Earth previously experienced warm climate states, these were characterized by extreme climate events and were radically different from our modern world. Since the peak warmth of the Hothouse, Earth’s climate has gradually cooled over the last 50 million years, but the present and predicted rapid anthropogenic changes reverse this trend and, if unabated, far exceed the natural variability of the last 66 million years. CENOGRID’s window into the past provides context for the ongoing anthropogenic change and how exceptional it is.”
While the rough framework of a global climate reference curve has existed since 2001, climate records from many new sediment cores greatly improved in recent years. Over the last two decades, scientific drilling specifically targeted older geological strata, especially older than 34 million years, giving researchers access to better material for reconstructing global climate in much greater detail than ever before.
Lead author, Dr. Thomas Westerhold (MARUM, University of Bremen), said: “We now know more accurately when it was warmer or colder on the planet and have a better understanding of the underlying dynamics and the processes that drive them. The time from 66 to 34 million years ago, when the planet was significantly warmer than it is today, is of particular interest, as it represents a parallel in the past to what future anthropogenic change could lead to.”
For more on this research see 66 Million Years of Earth’s Climate History Uncovered.
Reference: “An astronomically dated record of Earth’s climate and its predictability over the last 66 million years” by Thomas Westerhold, Norbert Marwan, Anna Joy Drury, Diederik Liebrand, Claudia Agnini, Eleni Anagnostou, James S. K. Barnet, Steven M. Bohaty, David De Vleeschouwer, Fabio Florindo, Thomas Frederichs, David A. Hodell, Ann E. Holbourn, Dick Kroon, Vittoria Lauretano, Kate Littler, Lucas J. Lourens, Mitchell Lyle, Heiko Pälike, Ursula Röhl, Jun Tian, Roy H. Wilkens, Paul A. Wilson and James C. Zachos, 10 September 2020, Science.
CENOGRID is a lasting international legacy of 50 years of scientific ocean drilling now led by IODP. The authors see CENOGRID as a basis for researchers worldwide to correlate their data to and place it within the context of Earth’s climate history. With more data, it is now possible to not only further refine the picture of the climatic past, but also to identify regional intricacies. The authors emphasize that this is fundamental for testing the reliability of climate models for the future.
The UCL contribution was funded by a Horizon 2020 Marie Skłodowska-Curie Action Fellowship to Anna Joy Drury.
As the “More on…” items below the article attest, carbon dioxide is not the only important greenhouse gas; methane & water also figure.
“Since the peak warmth of the Hothouse, Earth’s climate has gradually cooled over the last 50 million years, but the present and predicted rapid anthropogenic changes reverse this trend and, if unabated, far exceed the natural variability of the last 66 million years.”
5000–7000 years ago, for reasons I’m not certain of, it was reportedly warmer here than at any other time since the last glaciation. As for the “predicted… changes,” they haven’t occurred yet & so don’t qualify as data.
Furthermore, labeling their data with modeled projections as the Anthropocene Age, which is not officially approved, says a lot about their agenda.
Just looking at the graphs provided, the anthropogenic interpretation seems a bit at odds with the significant rise by the look well before 1850, with a change of scale followed by projections based on conjecture. Such presentation makes it feel like another study trying to prove the ‘right’ answer.
Then I saw this: https://shepherdgazette.com/cooling-the-hothouse-watts-up-with-that/
” . . . little-to-no global ice volume during the Hothouse and Warmhouse compared to the Coolhouse and Icehouse.”
Wait a minute! I thought all life on earth dies when the climate warms. You mean to say life actually survives and thrives regardless of the CO2 content? But that doesn’t jibe with the Left’s rhetoric. How are they going to rewrite THIS narrative?
dont worry jeezus will save us!!!
Yes, the world has been hotter before and things lived and adapted. This and associated changes occured over thousands to millions of years, where there could be something much more akin to an equilibrium between climate and existing life. Please read the axis scales of this plot, people. The point is that there has been an irrefutable sharp uptick in temperatures over the timespan of a few human generations that is approaching the scale that previously took thousands and thousands of years to happen. The Earth is severely out of equilibrium, and it is difficult to come up with another explanation from the data that is not human-derived. We can keep doing what we are doing and the Earth will survive just fine, but we cannot expect to be so lucky. Take your pick of plausible outcomes: population collapse of various ecosystems and their ripple effects on food availability (crops, livestock, fish, etc), scarcity of clean and cheap drinking water, overall reduction of livable places, among God knows how many others. This isn’t a partisan fight folks! Everyone should be concerned and the fight should be over the first steps to take to mitigate the coming damage, not whether it’s all hocus pocus from the liberal media and academia. Please take this seriously.
Good job, Joel.
My guess is they won’t get it though.
So much for common sense these days…
You said, “The point is that there has been an IRREFUTABLE sharp uptick in temperatures …” Well, for starters,we came out of a major glaciation at least 12,000 years ago, and sea level changes show that melting of ice and thermosteric increases have been nearly constant for about the last 8,000 years, except for the Little Ice Age, which saw glaciers advancing in the Alps and the Western US. Something that you apparently don’t understand is that there is a general principle that the farther one goes back in time, the coarser the temporal resolution of changes such as temperature. That is, spikes such as have occurred since the end of the Little Ice Age get lost when the ability to date rocks has an uncertainty of greater than 100 years. Even so, the graphs in the article show very abrupt spikes that are comparable to what appears to be happening at the moment.
The concern is not about what has happened, but about what unvalidated global circulation models forecast for future scenarios. Something to consider is that the tropics represent about 3% of the surface of the Earth, but contain about 50% of the known species. Warming doesn’t sound like a death sentence to me. On the other hand, many of your concerns are more directly correlated with world population than CO2 levels.
You can’t splice 2 graphs together like that.
The 2nd graph is ok. It doesn’t show warming.
Don’t discredit science just cause you can’t figure it out, guys. Took you for bots at first… guess AI’s smarter though.
“We now know more accurately when it was warmer or colder on the planet and have a better understanding of the underlying dynamics and the processes that drive them. The time from 66 to 34 million years ago, when the planet was significantly warmer than it is today, is of particular interest, as it represents a parallel in the past to what future anthropogenic change could lead to.”
But then at 33 Myr ago (late Eocene) atmospheric CO2 was more than double what it now is and the climate was mild and not a hothouse. The polar ice caps were beginning to form. This should show us what anthropogenic change could lead to. Nothing catastrophic. Except maybe politically?
CO2 should not be the focus. While it will deteriorate what has been a very stable climate, more important issues are over population and toxicity. Last time I checked, burning fossil fuel produces very toxic gas for us humans to breathe. Humans can live for a couple of months without eating, a couple of days without drinking, and a couple of minutes without breathing so why hasn’t the idea of spewing toxic gasses into the air being talked about much. Making the air poisonous is tantamount to suicide. By the way, climate change is already affecting us in a big way. Don’t believe me? Look into hay production. Also, 66 million years ago there was a sudden change in climate and what was the result? So no one should trivialize or politicize this issue. Earth is our (that means all of us) only home.