Claim: Episodic and intense rain was caused by ‘ancient global warming’

From the University of Bristol and the “models before measurements” department comes this highly speculative claim that is entirely based entirely on climate models. There’s no actual measured data from any sort of paleo research. It’s science, but not as we know it.


A new study by scientists at the University of Bristol has shown that ancient global warming was associated with intense rainfall events that had a profound impact on the land and coastal seas.

The Palaeocene-Eocene Thermal Maximum (PETM), which occurred about 56 Million years ago, is of great interest to climate scientists because it represents a relatively rapid global warming event, with some similarities to the human-induced warming of today.

Although there have been many investigations of how much the Earth warmed at the PETM, there have been relatively few studies of how that changed the hydrological cycle.

This newly published work shows that rainfall increased in some places and decreased in others, according to expectations, but that much of the world experienced more intense and episodic (or ‘flashy’) rainfall events.

Top panel shows modelled change in annual mean rainfall (as a percent) given a global warming at the PETM, ~56 million years ago.Bottom panel shows the same thing but for EXTREMES in rainfall. The key thing is that in some regions, the rainfall decreases (top panel is red) but the extremes in rainfall increase (bottom panel is blue), such as in southern Africa, the Amazon, or northern Australia. This is what we mean by a “decoupling”. Credit: BRIDGE – University of Bristol

Lead author Dr Matt Carmichael from the University’s Schools of Chemistry and Geographical Sciences, said: “With the same climate models used to study future climate change, we studied how a doubling of carbon dioxide concentrations would affect rainfall patterns on a world with Eocene geography.

“This increased the overall global precipitation – warmer air holds more water.  But it also changed the pattern and frequency of extreme events.

“The tropics became wetter and the incidence of extreme events increased, by as much as 70 percent in some tropical regions.

“In other places, total annual precipitation and the number of extreme events became decoupled; in other words, they became drier, with less frequent but more extreme events.  All of this illustrates the complexity of how global warming will affect our local, regional and global rainfall patterns.”

Co-author Professor Rich Pancost from Bristol’s School of Earth Sciences, explained how these findings agree with a range of geological and chemical features of the Palaeocene-Eocene global warming.

He said: “This warming event is associated with major changes in how soil and sediment were eroded and moved around the landscape.

“In many places, river systems that had been transporting silt or sand became associated with fist-sized rocks or even boulders; and more sediment was transported to and buried in coastal margins. In some locations, the rate of sediment accumulation increased by a factor of ten. But at the same time, there is also evidence that these systems became more arid.

“Our climate simulations reconcile this for many locations, showing an increase in aridity with fewer but more intense rainfall events.  Those events were likely responsible for increased energy in these systems, moving around more material and larger objects. Ultimately it flushed more sediment to the ocean, causing eutrophication, blooms of algae and in some cases hypoxia.”

Co-author Professor Dan Lunt from the School of Geographical Sciences added: “There are many similar events in Earth history, where warming appears to have been associated with changes in rainfall and sedimentary systems.

“Although we have not investigated them here, it is very likely that our results are translatable – because the physics that underpins them remains the same.  Thus, the collective body of research confirms that global warming in the past and the future will be associated with more ‘flashy’ rainfall, with implications for flooding and water management.”

Professor Pancost said: “Past climate has lessons for our future.  Not only do the models show evidence for more intense rainfall events – with all of the implications that entails – but they are consistent with all of our other data.

“In fact, they explain inconsistencies in our other data and confirm some long-established hypotheses. In doing so, they foreshadow our potential future with complex and dramatic changes in rainfall, more flooding and more soil erosion.”

The Paper:

‘Changes in the occurrence of extreme precipitation events at the Paleocene-Eocene thermal maximum’ by M. Carmichael, R. Pancost and D. Lunt in Earth and Planetary Science Letters

Abstract

Future global warming is widely anticipated to increase the occurrence of extreme precipitation events, but such hydrological changes have received limited attention within paleoclimate studies. Several proxy studies of the hydrological response to the Paleocene–Eocene Thermal Maximum hyperthermal, ∼56 Ma, have recently invoked changes in the occurrence of extreme precipitation events to explain observations, but these changes have not been studied for the geologic past using climate models. Here, we use a coupled atmosphere–ocean general circulation model, HadCM3L, to study regional changes in metrics for extreme precipitation across the onset of the PETM by comparing simulations performed with possible PETM and pre-PETM greenhouse gas forcings. Our simulations show a shift in the frequency–intensity relationship of precipitation, with extreme events increasing in importance over tropical regions including equatorial Africa and southern America. The incidence of some extreme events increases by up to 70% across the PETM in some regions. While the most extreme precipitation rates tend to relate to increases in convective precipitation, in some regions dynamic changes in atmospheric circulation are also of importance. Although shortcomings in the ability of general circulation models to represent the daily cycle of precipitation and the full range of extreme events precludes a direct comparison of absolute precipitation rates, our simulations provide a useful spatial framework for interpreting hydrological proxies from this time period. Our results indicate that changes in extreme precipitation behaviour may be decoupled from those in mean annual precipitation, including, for example in east Africa, where the change in mean annual precipitation is small but a large increase in the size and frequency of extreme events occurs. This has important implications for the interpretation of the hydrological proxy record and our understanding of climatic, as well as biogeochemical, responses to global warming events.

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77 thoughts on “Claim: Episodic and intense rain was caused by ‘ancient global warming’

  1. “that is entirely based entirely on climate models”

    Department of Redundancy Department?

    PS: The notion that averaging 10 wrong answers to get the right answer only makes sense in “climate science”.

      • Walter Sobchak

        I must admit to having had to look “onanism” up.

        No idea how I got away with for so long in my youth.

        I was assured it was something else that would make a young man go blind.

        • It’s Biblical, Onan was the brother of ???? who was killed by the elders, for some misdemeanour or other, anyway, that left his wife Tamar without seed. Younger brother in tradition had to lay with his sister-in-law to produce offspring, only he didn’t want any, thus he was allegedly guily of pleasuring himself thus “spilling his seed”!

          • Onan’s crime was coitus interruptus, but his name has been hijacked, so to speak, as the polite term for masturbation.

            In 1879, Mark Twain delivered his most notorious after dinner speech before the all-male Stomach Club in Paris, entitled “Recent Improvements in the Science of Onanism” or something along those lines.

          • Oh, you just had to do that, John! Now I have to dig that up. I really do need a good laugh. These “scientists” (lab rats running computers) give me overt flatulence.

          • That’s why I like it so much! AND I’ve learned so much too! I understand that such practices were fairly common place in many parts of the world! I refer to the Intellectual Elites, you know, those who know what’s good for everyone (else), as Intellectual Onanists! Well, at least I don’t have hairs on the palms of my hands!!!! 😉

      • Except, they are already blind, deaf, without common sense, lacking logic, etc…

        Is there a limit they can reach in their self satisfaction seeking depravity?

  2. Even the IPCC admits that climate models are only accurate when they are averaged over the entire earth.
    They are no good at predicting regional or local weather.

    On the other hand, activists continue to try and use the models to do just that.

    • MarkW

      Hottest summer EVAH in England this year, that is if it’s not the British Isles, and Scotland, Wales and N. Ireland are excluded.

      Reliably announced on the BBC today.

      So that confirms it. Climate change is regional.

        • Alan the Brit

          As far as I could gather it was the average temperature, which undoubtedly included Heathrow, Gatwick, Luton, Stanstead, Midlands airport etc.

          From memory I think they said that across the UK the average didn’t reach that of 1976 and a few others. Which in one way was honest of them to state but the meaning was lost with the sensationalist headline.

          Had they said “The UK was cooler this summer that in previous years but England recorded an average temperature higher by (I think) 0.1C”, I would have considered that responsible reporting. But of course the BBC are desperate to promote AGW.

        • During takeoff, a Boeing 777 burns about 800 lb/min of fuel per engine (1600 lb/min total). A pilot acquaintance of mine said there are 3000 airline flights crossing the north Atlantic every night. Do you suppose there may be some heat pollution near airports – especially international airports??

    • I just wanted to note, I agree with your numbers here. Most climate scientists will try to exaggerate the numbers for this event, but the ones you quoted are the accurate ones.

      • Bill,

        Thanks for backing those numbers up.

        I’ve seen some pretty seemingly indefensible estimates, apparently politically motivated.

  3. My, albeit limited, understanding of the PETM is that it involved 6C to 8C of warming in less than 100,000 years. What relevance has that to our modern AGW scenario? The attempt in the paper to link CO2 levels to the PETM temperature rise also appears to be extremely weak. The CO2 forcing is inferred, no more. This is hardy surprising since, in the context of the data and chronology available from the 50 million year plus fossil record, you can’t possibly say whether any change in CO2 level, even if you could measure it accurately, led or lagged the temperature rise.
    The authors give it away in the abstract somewhat with their comment: “the most extreme precipitation rates tend to relate to increases in convective precipitation”. Quelle surprise! You wonder of the link to CO2 is simply there to elicit easy publication or the article and/or future funding.

  4. In all GCMs, the microphysics of cloud droplet formation, of precipitation-related intensity parameters, and of convection parameters are all hand-tuned and the value sets used are poorly constrained by observation, this is just hand-waving at best, outright garbage at worst.

    They are tuning the very thing they are outputting and calling it science.

  5. The coming fight now is Earth System Sensitivity. It has its roots almost as long as AGW. Back in the 80’s was when it really got started. Almost 40 years later Michael Mann and his followers have decided that the IPCC is doomed and that they dont need it anymore anyway. They are losing control over its alarmist message and it is becoming more conservative as we skeptics are forcing it to tone down. Witness the IPCC RCP8.5 which doesnt really look scary as far as temperature is concerned.
    The Earth System Science (ESS) Education Alliance was formed in 2000 and has ~50 institutions signed up with over 3000 teachers. Their plan is to take over the geology and paleontology departments of every university in the world just like have they done to the Atmospheric science faculties. In their minds they have to because then they can control the past. Eric Blair aka George Orwell has unwittingly written their manifesto. He who controls the past controls the future. He who controls the present controls the past. Orwell should have reversed those 2 sentences. The recipe is simple. The thesis is that long term changes of the earth(which the alarmists will say is ultimately caused by short term changes caused by CO2) will dwarf the measly short term temperature changes of CO2. To do that they need to control the past with different climate models because only with the past can they control ( model) the slow processes needed so that they will project far into the future 500 years if necessary. To do that they have to take over the 2 faculties that are standing in their way.

    I PREDICT IN THE NEAR FUTURE WE WILL SEE 1000’S OF THESE STUDIES OF THE PAST ALL SIMULATED BY COMPUTER MODELS. Sighhhhhhhhhhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!

    • To be fair to George Orwell, a committed Socialist, he was forewarning of Totalitarianism from the far left, & highlighting their desire for total control over others!

  6. “..The Palaeocene-Eocene Thermal Maximum (PETM), which occurred about 56 Million years ago, is of great interest to climate scientists because it represents a relatively rapid global warming event, with some similarities to the human-induced warming of today…”

    Wondering if the authors of this study realize the logic problem in this statement. If the warming in the PETM was “relatively rapid warming event, with some similarities to the human induced warming of today..” how do they know today’s warming has a significant human-induced CO2 signal?

    • They did a back-to-the-future simulation, where Marty McFly visits this period and multiple periods afterwards, changing the course of events in such a way that the automobile is never fully used as a mode of mass transportation, and the model simulation shows that Marty prevented a future where human CO2 does what some unknown factor did then. The model has not produced any reliable results as to what Marty knew caused that period’s “warming event”. This will require more model simulations, which will require more funding.

        • Being a synical old b’stard @ 60, I am having a small wager with myself that the warmistas will drag gravity into the AGW theory somehow! 😉

          • Alan the Brit

            We are of the same vintage, within a year or so.

            Reassuring, as climate sceptics in general seem to be older, with memories of the distant past, like 1976.

            Similarly, with Brexit; we remember the lies told to us by the Europeans, we remember the condition the country was in with the brain drain and 80+% income tax for high earners, we remember nationalisation and the complacency it bred, we remember the strikes, rabid unions, uncollected rubbish piling up on our streets, blackouts etc.

            Barely a week went by without one industrial dispute or another ravaging the country.

            We bitch if our broadband is down for an hour today, I remember when telephone lines were down for days before the GPO got its finger out it’s arse and decided to grace us with a repair to a service we paid through the nose for.

            Our youth really has no idea how bad things could get under a socialist government, because that’s what Corbyn and his communist sidekick would have the country operate as. Dire nationalised industries delivering services much worse than we have now.

            I don’t think we’re cynical, I think we’re practical and realistic.

          • Bingo! I’m a Canadian of 61 years and I was in Britain during the coal miners strike in 83?, I think. Scargill was a little Stalin wannabe and I was shocked at the state of the country and the political blindness I saw.
            I concluded that when people are pressured economically and try Socialism it makes them poorer and even more defensive, so they go deeper down that rabbit hole. Putting that train wreck into reverse is very difficult but absolutely vital.
            God Bless Margaret Thatcher!

          • John Harmsworth

            Scargill was a thug. I was a cop in Glasgow at the time and we were given the job of protecting the pickets at Ravenscraig and Hunterstone. We didn’t have much trouble, in fact it was largely good humoured. but on one occasion there was advanced intelligence that Scargill and his flying pickets were heading our way and the atmosphere changed like a light switch. Fortunately they were turned back.

            I had every sympathy with miners, I lived in a mining area and drank with them in local pubs, but Thatcher did what had to be done, not just with the pits but with all the nationalised industries.

            She made mistakes, the poll tax in Scotland was monumental, but she turned the country round.

          • HotScot,
            Much is made of the position on AGW, supposedly based on political view. However, I don’t recollect seeing any studies on how it varies with age. My sense is that those of retirement age are more likely to question the consensus.

          • Clyde Spencer

            We question the concencus because it’s like everything else we old gits have seen. The move from vinyl records to cassette tapes, then VHS/Betamax tapes, onto CD’s/DVD’s, Blueray and then streaming.

            The political scares over mass unemployment, to much employment, inflation of the economy, deflation, Y2000 bug, Vietnam, Iraq, kids watching TV, then computers, then mobile phones.

            Remember Carnaby Street? Mini skirts? Abhorrent! Day to day life now. Gay’s, greens? Almost unheard of until the 60’s and 70’s, but the overt closet revelations are becoming commonplace, so no one cares anymore.

            Everything new is presented as a political opportunity then reported as a social disaster.

            It is truly tedious. AGW has longer legs than the rest, but it will also suffer the fate of failure.

            I just wish it would hurry up.

    • Good. The first true primates evolved from proto-primates around then. As forest creatures, our arboreal mammal ancestors liked it hot and moist.

      During the PETM these true primates spread throughout Asia, Europe and North America, via Greenland, plus possibly to Africa. The basal omomyid Teilhardina reached all three northern continents.

      It appears that the omomyid family belongs to the same primate suborder, Haplorrhini, as do humans, other great apes, gibbons, Old and New World monkeys and tarsiers (all of which carry the same broken vitamin C gene).

      Another family, the adapids, thought to be ancestral to Strepsirrhini (lemurs ad lorises), also lived at that time.

      • I read somewhere recently the claim that the 3% of the land that represents the tropics contains 50% of the biological diversity of Earth. It can’t be all bad!

  7. flashy?….

    There are limits and constraints….and the whole world already experiences that
    Just ask anyone that tried to spend this past weekend in South Florida

  8. Sounds to me like our current form (model) of Forest Mismanagement will need to be looked at and revised (remodeled) into a newer form (model) of Forest Mismanagement to keep up with the pace of modeled Climate Change…

  9. The Eocene is rather well-characterized in California because of the economic importance of the gold found in the river and stream channels. There are abundant, red lateritic paleosols exposed throughout the Mother Lode and foothills of the Sierra Nevada. The interpretation of these paleosols, and associated fossils found in the river gravels, is deep weathering such as is found today in the Amazon Basin. That is, Tropical conditions with abundant rainfall. However, mapping of the Eocene rivers suggests large meandering rivers not unlike the lower reaches of today’s Mississippi River. While hydraulic gold mining of some of these larger river remnants often exposed a ‘Blue Lead’ that contained quartz cobbles and boulders, geologists of the Gold Rush period speculated that these were actually of Cretaceous age.

    The Eocene surface was initially covered during the Oligocene with latite and dacite flows originating along what is now the crest of the Sierra Nevada chain, and following the N-S major rivers. Following that were major ash falls that buried everything. When the Oligocene volcanic episode subsided, the easily-eroded ash was removed first, establishing new E-W river courses cutting across the pre-existing Eocene river drainage. In some places, such as around Sonora/Columbia (CA), the sinuous courses of the former Eocene river stand in stark relief on the horizon, locally known as Table Mountain.

    I would imagine that under the conditions postulated in the computer models, the meanders would be cutoff by the flood waters, and one would find boulders in the Sacramento Valley. However, one does not see meander-cutoffs, and the Ione Formation in the Sacramento Valley is largely composed of clays!

  10. In Lenar Whitney’s epic screed against Al Gore’s Inconvenient Truth (google Lenar Whitney Global Warming is a Hoax) where she stated that a child could disprove the scientists’ claim of global warming by using a “thermometer”, …. she then holds a rectal thermometer in her hand describing the PAUSE.

    When asked why illustrate using a rectal instrument instead of a more accurate scientific device she said that was easy. This came from where they pulled their data from…. out of their arse!

    Sounds like what the “scientists” at Bristol might be up to!@#$%

  11. So, as I understand it, these individuals do not bother to give even a tiny nod to the fact that tectonic plate activity – meaning continental drift – was going on during the 65million to 50++ million years ago?

    They should perhaps look at a map once in a while, something that kids will understand. There was FAR less land surface available than there is now. This map more than adequately demonstrates that premise.

    https://kids.britannica.com/students/assembly/view/214300

    I don’t know whether or not the link as I copied it will work, but you can copy it to your search block and find that map.

    Maybe if some of these cloistered fustercluckers had their electronic equipment taken away from them and were required to produce real world results instead of peculiar fairy tales, we’d get our money’s worth.

    What?? Well, I can dream, can’t I?

    • Sara,

      Sea level was higher, but with Greenland and Antarctica ice-free, I’m not sure how much less land surface there was, unless ice sheets count as land surface.

      But clearly, the position of the continents affects global climate and heat transfer via oceanic circulation.

      • Uh, try looking at the map at the link I provided. That’s 50+++ million years ago. A good geologist can give you information that these grant=grabbing persons can’t.

        There is plenty of evidence in fossil corals in the Bahamas to show that the sea levels rose and fell repeatedly, based on the layers of strong growth vs. weak growth.

        Geophysical evidence is more accurate than some modeling program cooked up in a university computer lab.

        These people are grasping at straws and it shows.

        • Sara,

          I’m familiar with Dr. Scotese’s work, from which your map comes.

          My point is that the key issue isn’t the amount of land surface, which might not differ much between now and then, due to an ice-free Greenland and Antarctica. The albedo of the land and sea is however important. More ice and whiter ice reflects more sunlight.

          As Mark notes, more extensive epicontinental seas raise ocean temperature. More active seafloor spreading also warms the oceans, and tropical currents able to flow freely around the world distribute the heat more evenly.

          Sea level has been higher for most of Earth’s history than now, although of course it’s lower during icehouse intervals such as at present, with so much water locked up in ice sheets. It was some 140 meters lower during the Last Glacial Maximum.

        • John – OK, sorry. I didn’t quite understand which direction you were coming from. You made it clearer.

          Continental drift seems to be badly misunderstood by the lab rats who run up data spreadsheets on computers.

          Apart from getting some more cash out of grant funding, I don’t know what their purpose was in producing this “report”. Any geologist could have come up with a similar result without looking silly.

      • John Tillman
        Sara,

        Sea level was higher,
        __________________________________________________

        JT, the nowadays subcontinent India over geological times wandered as sole tectonic plate over a vulcanic Hotspot.

        That + every year monsunes* makes the whole subcontinent India to one of the most fertile subcontinents on planet earth.

        So what’s the problem with “heat” and “flash floods”.
        __________________________________________________

        *India every year NEEDS and PRODUCES and WEARS OUT more than 1 Mil. umbrellas.

        India is crowded because people search for and thrive on exactly such conditions!

        • Johann,

          Yes, India is lucky to have the volcanic soil which it owes to having crossed the Reunion Island Hot Spot during its record high speed (in tectonic terms) trip across the Indian Ocean from Antarctica to collide with the Eurasian continent, producing the Deccan Traps flood basalt eruptions. Which passage happened around the Cretaceous-Paleogene boundary, roughly coincident with the celestial impact associated with the demise of the dinos and many other groups in the famous mass extinction event.

    • Not only were there more oceans, but the number of shallow seas was a lot higher as well.
      Shallow seas warm up a lot faster than do deep ones.

      We could also point out that ocean circulation patterns were vastly different as well.

      Of course none of those were factored into this “study” since their climate models only look at the atmosphere and assume that everything else is the same.

  12. Great, now, if they can only predict tomorrow’s weather as accurately, I will be happy to sign over my future to these one-world-government, (by them), socialist drongo’s.

  13. Please correct me if I’m wrong. My understanding of scientific gathering of evidence is that the primary requirement is observation, preferably multiple observations, and repeatability, both in a lab, and in the open. Therefore, science, without observations and repeatability, especially without others being able to get the same results, would be like “cold fusion” and not real science.

    • John Minich

      That’s also my uninformed perception. Yet there hasn’t been a reliable, credible, empirical study conducted that demonstrates CO2 causes the planet to warm. That’s at least 40 years of the best scientific minds in the world working furiously to prove the relationship. There should be dozens, if not hundreds of studies by now but there’s not one.

      Amazing anyone with half a brain would consider committing the worlds population to an unproven hypothesis. Which, to me, is fairly conclusive that the whole scam is just a political ploy from the left to impose global socialism.

  14. Are these computer geniuses going to try to blame this nonsensical and alleged fluctuation stuff on humans? Just asking, because we did not exist as a species until Homo Erectus showed up, and that poor soul died out or was bred out by other Hominids. So that’s – what? 3.2M to 1.5M years in the past, not even close to the time frame of this “study”.

    You know, if they’re out of something to do, I have laundry and vacuuming that need to be done.

    • Sara,

      H. erectus is considered a different species from H. sapiens. It existed from c. 1.8 million years ago until replaced by H. heidelburgensis-grade humans some 500,000 years ago. H. erectus might have survived in Java until as recently as 140 Ka, or even later, if H. floresiensis be a dwarf variant of H. erectus.

      https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021562

      https://www.sciencedirect.com/science/article/pii/S0047248417300866?via%3Dihub

      At 3.2 Ma, our genus Homo, as presently defined, didn’t yet exist. Rather the hominins at that time belonged to genus Australopithecus. IMO however, all hominins should be assigned to Homo. Some specialists think that genus Pan, ie chimps and bonobos, should be subsumed under Homo as well.

      As currently classified, the first member of our genus was H. habilis, extant from about 2.1 to 1.5 Ma. It evolved into H. erectus-grade humans, followed by H. heidelbergensis, from whom Neanderthals, Denisovans and anatomically modern humans arose.

      But, obviously, you’re right that humans and hominins were far in the future during the PETM, as were other modern primates.

      • I know, John, but sometimes, I like to “compress” things to save space. And as you understand, my point is that we, as a genus (Homo), which branched out into other species of many, many kinds, weren’t even around to witness what went on.

        The rise of mammals came out of this post-dinosaur epoch. The grant guzzlers ignore that in their quest to get more money. I’m not sure what the point was to the production of their “essay”, other than getting more grant money, but they haven’t produce anything that any reasonably good geologist could have produced, and most likely already has.

        And I have no idea what the grant-seekers were trying to prove that is NOT already known in geology. That there were more and shallower seas back then is already widely known. The Sand Hills in Nebraska are the remains of some of that, and I live in an area that is not too far north of the delta that formed the Mazon Creek fossil beds 300 million years ago. I have a shrimp fossil from that epoch that I picked up on a museum field trip. It is part and parcel of the temperate planet process.

        That this readily-available information, which is common knowledge in geology, is ignored by these lazy people so that they can get more cash for doing nothing is just appalling. In fact, it makes entire “climate warming” schtick cheaper and more ridiculous.

        • Sara,

          As you know, the Great Plains were indeed covered by a warm, shallow epicontinental sea during part of the Cretaceous Period, in which, like the Paleocene and Eocene Epochs, Earth enjoyed a Hothouse climate. But the sea had receded toward the Gulf of Mexico and Arctic Ocean by the PETM.

          IMO, regardless of the merits or lack thereof of this paper, the PETM is worthy of study, but not because it can serve as some kind of model for the present or near future of our planet. As noted above, it was already a lot hotter than now, even before the spike, and Earth got at least as hot as its peak later in the Eocene.

          The Sandhills are interesting for their much more recent geography. The dunes were active during Medieval Warm Period (~1 Ka), when the region was about one degree C hotter than now, and the Holocene Climate Optimum (~5 Ka), if not also during the Egyptian (~4 Ka), Minoan (~3 Ka) and Roman (~2 Ka) WPs.

          Drought in those warm intervals meant that the Ogallala Aquifer didn’t recharge up to it present level (or its level before drawdown for irrigation), so the vegetation which stabilize the dunes couldn’t grow. Not held in place, the sand was swept by the wind.

          Just one of the places around the world showing that previous intervals warmer than now have occurred cyclically during the Holocene and prior interglacials.

  15. “With the same climate models used to study future climate change, we studied how a doubling of carbon dioxide concentrations would affect rainfall patterns on a world with Eocene geography.”

    Playing with fantasies, while treating models and tuned outputs to be representative of other than personal confirmation bias.

    More wasted funds and computer time.

    • This Eocene geography would also have to include Eocene ocean currents (including thermohaline circulation), Eocene topography, Eocene CCN (Cloud Condensation Nuclei) production and Eocene vegetation/albedo. All very important for precipitation, all very different from today and all very imperfectly known.

      We don’t even know for sure if there was ice in Antarctica or not.

      • Ice/snow in Antarctica would depend on how far south that continent had migrated, and how much influence it had on ocean currents at that time.

  16. I am still waiting for 6 numbers for the National Lottery, I know their puter modul is that clever!!!

    Seriously, what possesses these “scientists” to believe they can foresee the future?

  17. “In many places, river systems that had been transporting silt or sand became associated with fist-sized rocks or even boulders; and more sediment was transported to and buried in coastal margins. In some locations, the rate of sediment accumulation increased by a factor of ten. But at the same time, there is also evidence that these systems became more arid.”

    This refers to braided river deposits. They do indicate strongly varying and intermittently intense precipitation. However the piece about “more arid” is extremely dubious. This is often claimed because at the present time braided rivers are most common in arid areas. However, in contrast to what is usually said in textbooks, if precipitation and sediment supply are sufficient braided rivers can occur even in rainforest areas. See for example here, one of the finest braided rivers I have ever seen, in northeastern Taiwan, an extremely wet area with almost untouched subtropical rain forest:

    https://www.google.com/maps/@24.5922716,121.509282,2595m/data=!3m1!1e3

    • tty,

      It is my impression that braiding represents a stream system where the particles in the bed load (because of their size), and the quantity of sediment, are too great to be moved by the available water and gradient. Thus, the water tends to move around the larger cobbles and boulders, except during floods.

      Some of the best examples I have seen are wide streams in the mountains of the northern part of the South Island in New Zealand. New Zealand is no stranger to rain!

      The Eocene river deposits in California don’t resemble braided streams. Although, they are often poorly sorted, suggesting deposition by flood stage.

        • tty,
          I don’t know how well they have been dated, but Eocene paleosols are fairly abundant in the western foothills of the Sierra Nevada. The PETM was a fairly short-lived event, which would have been sandwiched between the speculated Cretaceous ‘Blue Leads’ and the late-Eocene paleosols covered by the Oligocene volcanics. There has probably not been a lot of incentive to work out the Paleocene terrestrial stratigraphy in California.

  18. Amazing that people actually get paid for ‘research’ which involves clicking the “Run the made-up algorithm again” button!

  19. From the University of Cardiff and the University of Bristol:

    ‘An analysis of 50 years of rainfall data in arid regions by researchers at Cardiff University and the University of Bristol in the UK has shown a decline in rainfall intensity, despite an increase in total rainfall. The findings run counter to research that suggests that global warming causes heavier rainfall, because a hotter atmosphere can hold more moisture, and warmer oceans evaporate faster, thus feeding the atmosphere with more moisture.’

    https://meteorologicaltechnologyworldexpo.com/en/industry-news.php?release=d2cdf047a6674cef251d56544a3cf029

  20. I wonder where they got the observations that rivers carried fist sized rocks and boulders several million years ago? ….. apparently their models double as magic time machines.

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