Study reveals climate shifts through the eons

From the UNIVERSITY OF QUEENSLAND and the “climate change is not just a recent phenomenon” department.

Shelf sediments reveal climate shifts through the eons

Shelf sediments reveal climate shifts through the eons. JOIDES Resolution. CREDIT Arito Sakaguchi & IODP/TAMU

Climate change around Antarctica can severely affect Australia’s rainfall and even influence the distribution of wet and dry zones across southeast Asia, an international study has revealed.

Chelsea Korpanty of The University of Queensland’s School of Biological Sciences worked on the study, which was led by Dr Jeroen Groeneveld from the Center of Marine and Environment Sciences at the University of Bremen, Germany.

Ms Korpanty said global climate underwent significant change about 14 million years ago when the Antarctic ice sheet expanded.

“The new study presents shallow-marine sediment records from the Australian continental shelf, providing the first empirical evidence linking high-altitude cooling around Antarctica to climate change in the subtropics during the Miocene era,” she said.

“Our data is consistent with the inference that expansion of sea ice around Antarctica resulted in a northward movement of the westerly winds.

“In turn, this may have pushed tropical atmospheric circulation, shifting the main rainfall belt over large parts of Southeast Asia.”

The study used sediment cores drilled along the west coast of Australia during International Ocean Discovery Program Expedition 356 with the research vessel JOIDES Resolution, providing a long-term history of how rainfall and aridity changed on Earth from 16 to six million years ago.

Ms Korpanty worked aboard the JOIDES in 2015 as a sedimentologist alongside scientists from 29 different international institutes and with expertise across paleontology, sedimentology, and physical geological properties.

The results of the expedition, and the data published in the paper, provided an unprecedented climate record for western Australia, capturing when and how Antarctic climate changes affected Australian climate conditions.

Dr Groeneveld said the new study had the enormous advantage of using a complete and thus continuous sediment record which had not been influenced by potential drilling disturbances.

“Today the climate in western Australia varies from north to south – in the north the seasonal monsoon brings pronounced dry and wet seasons, farther south the climate is dry throughout the year, and in the south the westerly winds bring rain during the Australian winter,” he said.

Expedition 356 aimed to determine how this climate gradient developed over longer time periods, especially in the Miocene and Pliocene (16-six million years ago).

Dr Groeneveld said that over longer timescales, tectonic changes played an important role, such as in the closing of the Indonesian Gateway and the northward movement of Australia away from Antarctica.

“Global climate during the Miocene era was much warmer than today, and at the end of the middle Miocene a large part of Antarctica became glaciated and continued to cool the Southern Ocean into the late Miocene.”

The researchers used the natural gamma-ray data acquired with downhole logging during the expedition to reconstruct variations in river runoff and dust and relate these to a history of precipitation and aridity for western Australia.

The findings are published in Science Advances (doi: 10.1126/sciadv.1602567).

###

Advertisements

65 thoughts on “Study reveals climate shifts through the eons

  1. We tend to lose sight of the infinitesimally small slice of time we are living through (a few decades compared to the billions of years the Earth has existed) and hence the futility and hubris of imagining we can control something as massive and inexorable as the climate. It has changed, is changing and will continue to change until the planet is consumed in the death throes of our star.

    • Trebla, a very important point indeed. Humans have evolved to develop a very limited perspective. Many have difficulty comprehending time scales beyond 100 years (mostly because of our short existence) and have no concept of the vast distances that separate us from other objects in the universe (even the close ones). This tends to force many to see every phenomena as immediate, and close to home, when indeed it is not, and enact overcorrections that will have no beneficial effect and will only make things worse.

    • The most important comment that is missing from the ever bent d clarTions by the “experts”.
      Well said

  2. > From the UNIVERSITY OF QUEENSLAND and the “climate change is not just a recent phenomenon” department.

    I seriously doubt the “Department of climate change is not just a recent phenomenon” at the UNIVERSITY OF QUEENSLAND consists of much more than a document shredder to dispose of any candidate’s thesis that suggests such heresy.

    • It’s a good thing that the “climate change is not just a recent phenomenon” department is at the Anthony Watts logical posting departments and not at Queensland!

  3. Anything that happened to the climate 14 million years ago has little to do with today’s climate.

    The isthmus (of Panama) was formed around 2.8 million years ago. This major geological event separated the Atlantic and Pacific Oceans and caused the creation of the Gulf Stream. link

    The current ice age, along with the arctic ice cover, is probably due to the change in ocean currents that resulted as the seaway between North and South America began to constrict 4 million years ago. link

    • Since at present, we only have one earth to study, it helps to study how climate has shifted over time in response to the changing earth. It’s as close as we are going to get in the next couple hundred years to having other earths to study.

      • Yup! We can’t build a model that properly explains today’s climate so expert opinions on how climate worked millions of years ago are pretty suspect. It’s easy to sound confident talking about things that can’t be verified. Great to study-we just shouldn’t speak as if we really know.

      • What?! You mean the “Hitchhikers’ Guide” series wasn’t a documentary? Earth 2.0 should have given us all those answers.

        [But it did. And the answer was 42. .mod]

      • Agreed, john harmsworth. the same actually goes for nearly all aspects of “science” that has developed since around 1900, and probably earlier. Mathematical models tend to support much of the postulates about science since then, but that is not verification and it amazes me when I read such things as “we know carbon dioxide was over 4000 ppm in the past” or “we know that the temperature was 10 degrees warmer in the past.” we don’t actually “know” that but we derive that from proxies and definitions of what they show. Actually we know only what the data says, but we DON’T know if the data is interpreted correctly. We speak of the Sun and say “confidently” that the Sun IS this, works this way, whatever, but we don’t KNOW that. And then we build models on what we THINK we know and wonder why they don’t work. The human ego and vanity are far bigger than our actual true knowledge.

      • we don’t actually “know”
        =======
        I expect in 500 years humans will look upon us a backward, ignorant and superstitious. Exactly as we see people that lived 500 years ago. and like beliefs from 500 years ago, virtually all of science today will have been found to be incorrect and replaced by a better understanding of the worlds around us.

        yet we are only now learning that stone age people at the time of Stonehenge had the skill to perform successful brain surgery on people with severe head trauma from clubs, rocks, etc. Interestingly they used the same 3 corner cut used in modern brain surgery, and they understood the anatomy of the skull, what would kill the patient and what was safe. perhaps we are not nearly as advanced as we believe.

      • Tom O, in the same sense I don’t “know” that the high yesterday was 85F, that’s just what the instrument read.

    • Important geologic events in the Cenozoic Era glacial epochs:

      1) Eocene/Oligocene, ~34 Ma: deep ocean channels open between Antarctica and South America and Australia, creating the Southern Ocean and isolating Antarctica. The East Antarctic Ice Sheet forms as a result.

      2) Oligocene/Miocene, ~24-14 Ma: A smaller plate intervenes in Drake Passage, temporarily shoaling this stretch of the Southern Ocean.

      3) Pliocene/Pleistocene, ~3 Ma: The Isthmus of Panama forms, connecting North and South America by land, interrupting tropical ocean circulation and strengthening the Gulf Stream. Northern Hemisphere ice sheets start to form, wax and wane.

      4) Pleistocene, ~1.8 Ma: A shallow seaway reforms across the Isthmus, but without a major impact on ocean circulation.

      • I think the formation of the Isthmus actually made the north Atlantic warmer.

        When the ocean between North America and South America was at least 150 metres deep, the Gulf Stream would have flowed straight across the Isthmus and joined up with the ENSO currents at the equator in the Pacific. Without continents stopping it, the ENSO currents are going to flow right around the planet in one continuous flow.

        The North Atlantic would have just had a mild mid-latitude gyre and there would be far less warm tropical ocean water pushing up to the far north.

        Now there is a question of when it actually became shallow enough to stop a good Gulf-Stream-like flow (at least 150 metres of depth is required) and that was probably well before the 2.8 million timeline. Maybe even 15 million years ago.

      • Bill,

        I agree that the Isthmus did make the Atlantic warmer, bringing more moisture to the higher latitudes, hence more snow.

        I’ve looked into the Miocene and Pliocene Inter-American Seaway shoaling process, but can’t say when its effect on the Gulf Stream became pronounced. My impression is that the seaway narrowed but that a deep channel remained throughout at least most of the Pliocene. Could be wrong.

        Panama remained a megalodon shark nursery ten million years ago, in the late Miocene.

        http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010552

        Shallow water is good for nurseries, but the adults also needed access to deeper water to attack the giant turtles and cetaceans upon which they fed. Of course, whales also favor shallower water for breeding, and turtles need to come ashore.

      • To the extent that rocks and biomolecular clocks are accurate, it appears that Caribbean and Hawaiian monk seal evolution split apart at about the time of the formation of the Isthmus of Panama.

        Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology

        https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042687/

        The authors found that the time of divergence between the Hawaiian and Caribbean species, 3.7 Ma, corresponds to the closing of the Central American Seaway. The divergence between Mediterranean monk seals and the New World clade was dated to 6.3 Ma.

      • PS:

        In 2014, the (extinct) Caribbean and (extant, barely) Hawaiian monk seals were assigned their own genus, Neomonachus, separate from the Mediterranean monk seal, Monachus.

  4. Reading between the lines of recent output of the climate “scientific” community, they are experiencing a collective attack of anxiety as they gradually wake up to the fact that earth’s climate might have changed before the industrial revolution.

  5. Yeah, I have an Excel chart showing the same thing and how many times over the last 600,000 years. This is not news to me. I sure hope the people who do this research realize that they have no control over anything this planet does.

  6. “providing the first empirical evidence linking high-altitude cooling around Antarctica “
    Unless they are going for the Tropospheric hot spot in ancient times, I think ‘altitude’ should be ‘lattitude’.

  7. worked on the Resolution in the mid nineties as a tech. We had a name for the scientists – “pinheads” ‘cos they were so dislocated from reality.

  8. I don’t know about these guys / gals drilling holes and knowing what the weather was like during the past millions of years.
    I did study rainfall in Wellington, NZ, over the past 100 years and I know it follows a predictable pattern. Every 100 years, the same sort of pattern,
    must be something to do with the Gleissberg cycle?

  9. Remembering just how much variability there has been in climate over time is important. but some models are based on a very short time period, and the modelers act as if somehow does not matter that their model does not fit eras of the past.

  10. Well it’s Australian and its from the Unidiversity of Queensland. That’s two strikes against it. Although it points out that the climate has changed before, I’m not confident in the capabilities of an institution which has given a cartoonist a position at the Faculty of Climate Doom. Bad science (BS) that supports skeptical views is no better than BS that heralds climate Armageddon. Sorry, the entire subcontinent is self destructing economically, politically and intellectually because of the CO2 bogeyman, with international companies divesting because of loss of even high cost, unreliable electricity and the Peoples Republic of South Australia leading the way. We have a couple of hundred thousand climate scientists to keep recalculating the same linear formula engraved in gold. Writing off the worst of them only can improve the state of knowledge. JoNova is a brave dear warrior but with so little support for her herculean effort in the Oz wilderness, changing the tide there seems unlikely. It will be the last to let go.

  11. You don’t see that very often: An article on “Climate Change” that doesn’t refer to CAGW or CO2. These scientists actually used the phrase properly.

  12. To be geologically technically correct, the title should refer to epochs, not eons. The Miocene, Pliocene and Pleistocene are epochs (as is the Holocene, although unjustifiably so). Epochs make up periods, which make up eras, which make up eons.

    The Holocene Epoch is about 11,400 years old; the Phanerozoic Eon about 541 million. Both short because still on going.

    • As of course are the Neogene Period (24 million years so far) and Cenozoic Era (66 million years and counting).

      IMO the Oligocene Epoch should be in the Neogene instead of Paleogene Period, since Antarctic glaciation began in that epoch. But that would leave a short, two-epoch Paleogene, with just the balmy Paleocene and Eocence Epochs, first two of the Cenozoic Period.

  13. This is the new thing in the academic world Recycled Science™. Just take any long-known fact, do a re-write with a few PC cliches thrown in, and presto, you have the basis for a really impressive press-release. Zero risk in today’s dumbed-down environment, remember that an australian patent lawyer actually patented the wheel a few years ago, just to prove that it could be done.

  14. “In turn, this may have pushed tropical atmospheric circulation, shifting the main rainfall belt over large parts of Southeast Asia.”
    This is one of those things about climate papers that really pi$$ me off.

    Go investigate. Prove your supposition. Then publish. This is half baked science.

    • “In turn, this may have pushed tropical atmospheric circulation, shifting the main rainfall belt over large parts of Southeast Asia.”

      This is utter nonsense as any serious climatologist knows. The strength of the Monsoon is mostly regulated by the strength of the hot low pressure area over Asia which “pulls” the ITCZ northwards in summer. If the ITCZ was instead “pushed” north by the expansion of sea-ice and the west wind belt it follows that the Monsoon should reach further north during glaciations and retreat during interglacials. This is emphatically not the case.

  15. I hazard a guess that the separation of South America and Antarctica 27 million years ago had a major impact on ocean circulation. (sarc)

    • The separation really started about 50 million years ago, and became just deep enough for a good ocean current, the Antarctic Circumpolar Current, to start up at 33.6 million years ago. New oceans, separation of continents start out as rift valleys and then the ocean floods in and then after 25 million or so and more, they widen and deepen and become mature oceans. A good ocean current needs this depth to be at least 150 metres so it can take a long time before continents are really separated from each other.

      The final separation reaching a depth of at least 150 metres happened 33.6 Mya. The start-up of the Antarctic Circumpolar Current, isolated Antarctica in an extreme polar climate and it promptly froze over completely to the extent that ice-shelves extended out over the ocean to the end of the continental shelves. In other words, just as frozen as today.

      All this happened within 100,000 years, by 33.5 Mya and the global temperature dropped by 2.0C as a result of that extra sunlight reflecting ice. If you run the numbers on what this did to global Albedo, it results in exactly the 2.0C of temperature decline.

      But 27 million years ago, the glaciers retreated to about half of their current and 33.5 Mya extent. The Current was stopped by something and that is likely the small little cratons that exist between South America and Antarctica. There no longer was a good 150 metres of depth for a good current to flow.

      But by 14 million years ago, the cratons moved out of the way and the Current started up again and Antarctic started freezing over again. It didn’t get back to its 33.5 Mya extent until about 2.7 Mya when the ice ages started up again.

      These little cratons can still be seen today in the depth maps but most have sunk well below sea level now. At one time, they literally would have been large islands, but over time, these isolated smaller pieces of original crust sink into the mantle along with the ocean sea floor and become sunken continents/islands. They have also moved relative to South America since the main continent is moving west but these little cratons are not. It takes a good 25 million years for this to happen.

  16. Eons. Thats a whole lot a time, so what they are saying is humans are not causing climate to change it has just ALWAYS done that. Perhaps they should just come right out and say that?

  17. All of you do not appear to grasp the fundamentals. When the rotary lie detector drills for core through the ice the drill can only recover ice that is time date dependent and real. Greenland has its oldest ice core that is 430,000 yrs BP while Vostock 3 in Antarctica is 850,000 yrs sitting at approximately 150,000? yrs above basement. Greenland ice core has pine spores in it which when checked for DNA in the related bacteria adds another 300,000 years of mild terrestrial climate to the oldest ice at that location. It is clear that 1 million years ago there was NO ICE anywhere on the planet. A dramatic change to the climate saw the beginning of the latest round of ice accumulation in the Southern Hemisphere 1,000,000 years ago and delayed by 560,000 years until the repeat of that event took place in Greenland. Ice accumulation has been surprisingly constant since the respective start dates. The rates of accumulation are mostly unaffected by sea level change, CO2 changes, temperature changes and so on. Intriguingly, the base of the Vostok core is just above sea level suggesting that in spite of the ice succession above it there has been no sag in the earth’s crust located under the ice sheet.

    • There is ice that is much older than one million years in the Dry Valleys of the Transantarctic mountains. Pines don’t have spores.
      No ice older than MIS 6 is known from Greenland.
      Its Vostok not Vostock.
      Ice at Vostok is only about 420 KA, it’s the EPICA Dome C core that goes back 800 KA.

      And just how do you know the level of the land surface at Vostok before the glaciation?.

  18. Speaking of climate shifts, temps dropped to 32 F last night in my area. That is 7 degrees below average and 3 degrees from the record low for that day. What I find interesting is that temps in Greenland had started to warm from the 24th of April, and then dropped again over the last 4 days. Temps in the Arctic also dipped below average around 5 days ago on the DMI page, http://ocean.dmi.dk/arctic/meant80n.uk.php

Comments are closed.