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Eucalyptus trees cope fine with extreme heatwaves, defy climate models, survive 50C temps

What happens to a poor tree when you withhold rain for a whole month, then hit it with four days in a row of 43C temperatures? It was so hot, some of the leaves on these trees got close to 49-50 °C.

In at least one gum species in Australia, the answer is “not much”. They suck up lots of water from their deep roots and sweat it out til the heatwave passes. The trees become evaporative coolers “siphoning up” water. They cope so well, that not only did the trees not die, but their trunk and height growth were unaffected. Indeed, only about 1% of the leaf area even exhibited browning.

Extreme Heat Experiment, Gum Trees, field, Drake, 2018

Whole tree chambers in Richmond, New South Wales, Australia. Twelve 9-m-tall chambers in a field setting (a) enclose the canopies of individual Eucalyptus parramattensis trees rooted in soil (b). Two heatwave chambers can be seen on the left of the infrared image, along with several control chambers (c; temperature in °C).

But with global warming running at a heady 0.13C per decade, you might wonder how many years will it take for the trees to adapt?

From the paper — “one day”:

The gums rapidly increased their tolerance for extreme heat, the researchers found. Within a day the threshold temperature for leaf damage had increased by 2C.

Righto. At the current rate of warming, the world might get two degrees hotter in 150 years.  So these trees can adapt 55,000 times faster.

The researchers say the trees were not just likely, but remarkably good with heatwaves:

“We conclude that this tree species was remarkably capable of tolerating an extreme heatwave via mechanisms that have implications for future heatwave intensity and forest resilience in a warmer world.”

This research (yet again) fits the hypothesis that life on Earth is well adapted to a wildly variable climate, probably because it happened all the time.  The researchers even looked to see if exposing trees to hot weather first would help adapt them to extreme heat, but found it didn’t matter. The trees ability to adapt was innate. They just coped.

The models didn’t predict this

As the trees transpired more, they also stopped photosynthesising — they shut down in a survival mode. This breaks a pretty long standing biology rule, and thus breaks most plant growth models (and some climate ones too).  It’s pretty central to plant biology, leaves give up water to bring in CO2. As plants transpire more, they absorb more CO2 and turn it into carbohydrate (i.e. more plant) which is photosynthesis.  We now know that rule breaks under extreme heat when trees take a sauna-break, stop working, and just … sweat. I’d probably do the same if my leaves were 50C.

As usual in the news, no one mentions that the models were totally wrong on this, they just say, they found “the opposite” and it needs revising.

The Australian –

Scientists have long known about this evaporative cooling mechanism, known as transpiration. But current climate models suggest transpiration is closely related to trees’ photosynthesis rates, and that it declines during heatwaves.

The researchers found the opposite, with photosynthesis all but stopping but water use increasing.

“Our dynamic global vegetation models, particularly those that simulate the exchange of CO2 and water vapour between land and the atmosphere, will need to be revisited in light of these findings,” Professor Tjoelker said.

Then there is The Caveat we’ve come to expect. Good climate news always has a bad news rider:

He said it was a “good news-bad news story”, suggesting that scientists had underestimated gum trees’ resilience but over-estimated their carbon fixing capacity.

 Since the trees kept on growing after the heatwave, any loss of carbon fixation measured in days or hours, seems pretty minor in the planetary scheme of things.

Extreme heat, plant growth, photosynthesis, canopy temperature, graph, Drake 2018.

The temperature of leaves during an extreme experimental heatwave in the Austral Spring-Summer. Leaf temperature (Tleaf) measured in the upper canopy of each tree was strongly correlated with air temperature (Tair; a). Points reflect 15-minute averages of data collected during high light conditions (PPFD > 500 μmol m-2 s-1) from 2016-10-31 through
2016-11-03. The dashed line shows 1:1, the solid black line was fit to the data: (Tleaf = 1.38 + 1.02 * Tair – 0.0012 * Tair 2, P< 0.001, r2 = 0.8), and the solid red line shows the predicted leaf temperatures by the photosynthetic model. Histograms of Tleaf in high light conditions (PPFD > 500 μmol m-2 s-1, 12-16 hrs) in control and heatwave treatments (b-c) were constrained to values below T50. The T50 values are shown as the vertical dashed lines (b-c; blue = control or
before heatwave T50, red = peak heatwave T50). Note that some leaves in the heatwave treatment exceeded the T50 value observed pre-heatwave (dashed blue line) but did not exceed the T50 value observed during the heatwave (dashed red line; c).

 

These trees dig deep for water, but other types of trees with shallow roots need other solutions to cope with a month of no rain and 4 days of extreme heat. Apparently they have tricks like reflective leaves or they use heat-shock proteins to limit the damage. Obviously nature has dealt with hot temperatures before.

 

Thanks to Lance for help.

REFERENCE

Drake et al (2018) Trees Tolerate an Extreme Heatwave via Sustained Transpirational Cooling and Increased Leaf Thermal Tolerance, DOI: 10.1111/gcb.14037

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79 comments to Eucalyptus trees cope fine with extreme heatwaves, defy climate models, survive 50C temps

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    • #
      Dennis

      Ok, but it is not behind a paywall.

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    • #

      Wiping out greenhouse gas emissions is another big win. Driving electric cars powered by renewables could wipe out a massive six to eight per cent of Australia’s greenhouse gas emissions. That’s more than the entire state of South Australia.

      SA is close to being wiped out anyway.

      I love how self-interest avoids all the negatives about electric cars.

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  • #
    Dennis

    I understand that Eucalyptus have survived in Australia for at least 120,000 years.

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    • #

      Our backyard has around 30 x 100′+ gum trees and what is described is exactly what they do when we have a string of hot days. The yard gets littered with leaves and small branches as the gums get rid of what’s not required. Our entire region is much the same.

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    • #
      Graeme No.3

      Fossil eucalyptus leaves have been dated to 55 million years ago.

      60

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      Hanrahan

      Ghost gums, possibly Eucalyptus pauciflora survive, even thrive on the hot, rocky, dry hill over my fence. We are in our fifth failed wet season but they still look good.

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    • #
      Another Ian

      As have at least the other woody species in semi-arid and arid Australia – and the others too

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      • #
        Another Ian

        I realise that I have the wrong slant on this.

        Extended research funding will be required to demonstrate whether similar results apply for other semi-arid and arid species

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    • #
      Extreme Hiatus

      But never before have people treated them with so much cruelty.

      As Jo described it: “What happens to a poor tree when you withhold rain for a whole month, then hit it with four days in a row of 43C temperatures? It was so hot, some of the leaves on these trees got close to 49-50 °C.”

      That’s the opposite of tree hugging. That’s tree abuse. Where are the protests?

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  • #
    Roy Hogue

    Just my luck, the one tree I can’t tolerate being anywhere near. I not only can smell them I can taste them and my eyes and throat throw a fit over them. Oh woe is me!

    Seriously, they bother me like nothing else on Earth.

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    • #
      Roy Hogue

      :-( :-( :-( :-( :-( :-(

      Bad stuff to be allergic to because they’re favored very heavily as decorative landscaping just because they are tough, almost invincible, even in a drought.

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      • #
        Ted O’Brien.

        And we use eucalyptus lollies for sore throats! Sad to hear of your allergy, because for me the smell of “the bush” in a dry time has been one of the delights of life.

        In your backyard eucalyptus trees probably have few natural predators, so may become weeds.

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        • #
          OriginalSteve

          I spend time in Greece…they have eucalypts….

          Its confusing when you can see Greece but it smells of Australia….

          Mind you, wandering past a few more unfinished houses with reo still sticking up in the air confirmed where I was.

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          • #
            OriginalSteve

            Correction : “spent”…not “spend”

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          • #
            Annie

            Ah yes…all those pretty bits sticking up on top of the houses. It was the same in Cyprus, to do with house rates/taxes as far as I know. They were lower for an unfinished house!

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            Annie

            When I was a child we lived in Egypt for a while. There were eucalypts around the quarters and my mother used to pick a leaf and tear it to let us smell it. I experienced the smell of Australia long before I ever came here!

            There were eucalypts and wattles planted in Cyprus too.

            40

          • #
            AndrewWA

            15% of Portugal is covered in man-made Eucalypt forests.
            Enjoyed a meal in a guest house beside a river.
            The setting felt like being in Warrandyte on the Yarra River.

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            Another Ian

            In my slide collection I have a fine Australian sunset taken through Euc trees in South Africa.

            And a fine South African sunset taken through prickly acacia trees in NW Qld

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        • #
          Roy Hogue

          Ted,

          Thankfully there are none close to me.

          Interestingly the first eucalyptus trees were brought to this country by the railroads because they grow rapidly and the railroads wanted a source of cross-ties that could be cultivated easily and fast. So huge stands of them were planted in the central Valley of California.

          Little did the genius who thought that one up know that eucalyptus twists and cracks as it dries, making it unfit for anything but firewood. But being greasy wood it does make a hot fire.

          Then farmers noticed the varieties that grow tall and provide good windbreaks and gazillions of them were planted for that purpose, also along some highways.

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          • #
            John of Cloverdale WA

            Lived in LA for a couple of years and the smell of the eucalyptus trees made me feel at home. BTW, was that little genius, who sold a pup, a relative of Al Gore?

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            • #
              Roy Hogue

              I can’t say for sure, of course. But probably not. The great boom in railroad building began after the driving of the golden spike in 1869 at Promontory Point, Utah, marking the meeting of the two competing companies, one building east from Sacramento and one building west from the Mississippi.

              Anyway, that wolud have been a little early for Al Gore.

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        Another Ian

        Roy

        Don’t I recall that early in the LA smog “cure” it was estimated that the eucs growing there were contributing a considerable proportion of the problem hydrocarbons?

        20

        • #
          Roy Hogue

          Ian,

          Probably more than eucalyptus can contribute to smog. The Santa Monica Mountains are covered with brush that’s aromatic to some degree although I have no idea how much that contributes to smog. They call it grease-wood. But vehicle exhaust was clearly the major cause and great strides have been made in cleaning it up.

          I used to drive over the top of the grade into the San Fernando Valley and if the wind was right it pushed the smog down into the gap toward downtown Los Angeles and I could see it hanging there like a gray cloud. But it’s been years since I’ve been able to see that gray pall of smog.

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    • #
      Rereke Whakaaro

      Then you would be well advised to avoid going into the bush.

      There is a theory that God put all of His failed experiments into Australia. That is why there are more species, that can kill you with a glance, in Australia, than any other place in the world. The Bronx being second on the list.

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      • #
        Roy Hogue

        If outback Australia was so bad then how come it is that so many have gone there and survived it. Even Crocodile Dundee was able to get along there with his beautiful girl in tow. ;-)

        Not too bad for a nobody bridge painter until someone noticed him and sent him down the road to fame. He could even act a little.

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        • #
          Rereke Whakaaro

          I am not saying that the outback is bad. I am just pointing out that it can be deadly, to those not in tune with it. I would not go for a swim, in a lake, in the bush, however enticing, the water may appear. Water snake venom is worse than rattlesnake venom, I am told.

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          • #
            Roy Hogue

            RW,

            Rattlesnakes are not much of a threat unless you go stumbling through the underbrush without watching where you’re going. If allowed the chance the snake will retreat. And if it doesn’t, pick up a handful of gravel and toss it at the snake.

            My boy Scout days saw a number of them as we were hiking. Usually they warn you and the telltale rattle is hard to mistake. But sometimes they don’t so it’s also advisable to wear boots thick enough and calf high so the fangs can’t penetrate. I assume that going outback requires similar measures with clothing sufficient to stop a crocodile’s teeth. ;-)

            So the rule is, don’t look like a threat to the snake and it won’t be a threat to you. They know they’re no match for anything so much bigger than they are.

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            • #
              Roy Hogue

              Children and pets, on the other hand, require strict supervision out in the chaparral anywhere around here.

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          • #
            Cloudbase

            And our women are worse Rereke !

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        • #
          el gordo

          Roy you may be interested, eucalyptus has a reputation for draining swamps.

          90

      • #
        Annie

        I heard a theory that the Platypus was made up of all the bits left over from creating all the other animals!

        20

        • #
          Roy Hogue

          Ah yes! The Duck Billed Platitude. An interesting denizen of the English language for sure. ;-)

          Definition: a remark or statement, especially one with a moral content, that has been used too often to be interesting or thoughtful, usually having a bill like a duck. The Duck billed kind tend to be morally superior to anything else to the point of being obnoxious. Which is what I’m going to be if I stick around much longer.

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      • #
        Another Ian

        RW

        To add to Roy’s appreciation of Australia in the wild.

        One of our sons was driving home last Thursday night. Wearing thongs. Got out, walked off the bitumen for a leak and was bitten by a snake.

        Sensibly drove himself to the nearest hospital which wasn’t far away. Venom test didn’t ID the species. Muscular destruction test says it was a snake.

        He was out the next afternoon.

        Moral of that – if in need of a leak at night use the bitumen

        10

        • #
          Another Ian

          Roy

          For fine appreciation of the horrors of Australian wildlife from a US point of view I would recommend Bill Bryson’s “Down Under”

          20

          • #
            Roy Hogue

            Ian,

            Thanks for the recommendation. But right now I have my hands full with 2 writing projects, a science fiction novel and I’m determined to write down all the family history I know and leave it to my son and grandson. I’m the last person who knows what’s not already been forgotten and also has the will and the incentive to write it all down.

            Both projects will keep me going for quite a while. Among other things, my current wife, Catharine is my second wife, my first having died in 1992, and I have many memories of her I want to pass along to our son because I’m the only one with all those memories.

            I’ve been studying Australia slowly as I go along. Having rubbed elbows on the Internet with so many of you has shown me a picture of a place I would very much like to visit but for disability reasons that’s no longer an option.

            Discovering Slim Dusty was something I will never forget. He sings of the ordinary Aussie’s dreams, worries, problems and sometimes demons. The world should have more like him. He will be missed by many who will never even know of him but should have. The ordinary Aussie is every ordinary man everywhere, the man who keeps things going by his blood, sweat and tears, no matter what. And sadly, the world is becoming a place that will demand even more blood, sweat and tears. I don’t like it but can’t do anything about it except vote and speak against it.

            10

  • #
    Rereke Whakaaro

    The climate models do not allow for evolution.

    Nor do they allow for changes in human behaviour, in response to ever-changing political “incentives”, i.e. manipulation.

    The models say this … ! Reality says, “I don’t think so”

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  • #
    Another Ian

    Sort of fits here IMO

    “What are, in fact, the grounds for concern about global warming?”

    Javier – “This is an answer to the Geological Society of London position statement on “Climate Change: evidence from the geological record,” published in November 2010, and the addendum published in December 2013.”

    https://wattsupwiththat.com/2018/01/30/what-are-in-fact-the-grounds-for-concern-about-global-warming/

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    • #
      Kinky Keith

      It’s a long outline and covers everything about global warming you could think of.

      I couldn’t read it all, I got the message.

      Typically Stefan and Boltzmann were brought in to give an appearance of high level science. A sure sign of a lack of understanding of the basic science behind the supposed CO2 heat trapping mechanism. There is no mechanism that allows people to pontificate over the concept that “doubling of CO2 gives a 1 to 5 degrees rise. That’s scientific rubbish.

      No wonder people are confused, I’m confused just looking at the paper.

      Well spotted.

      KK

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    • #
      Kinky Keith

      Hi Ian,

      Had a look at the two documents put out by the Geological society. The first one from 2010 basically we are toeing the line and while they know and understand the Geological past, the present is not in their domain and they accept the IPICC portrayal of modern climate.

      The 2015 version is shorter and indicative of political pressure when they seem to be saying, ” we now believe in the human induced horror of CO2 greenhouse climate change and forever after hereby acknowledge our belief in CO2 the gas almighty”.

      Any reasonable scientist will acknowledge that CO2 cannot cause global warming.

      THERE IS NO HEATING MECHANISM RELATED TO CO2.

      The world has gone mad and we have lost control of our political elites when an engineering and scientific scam of this magnitude can be up and running for so long.

      The MONEY involved is uncountable.

      KK

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      • #
        Frederick Bennett

        So, would you care to elaborate on this a little further. What is the theory of atmospheric radiative transfer that suggests that THERE IS NO HEATING MECHANISM RELATED TO CO2 ? I don’t know of another theory that is based on fundamental physics that explains the observations very well. Just curious. It’s almost as if you are making a sweeping generalised statement about something you may not understand.

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  • #
    el gordo

    ‘On warm days, eucalyptus forests are sometimes shrouded in a smog-like mist of vaporised volatile organic compounds (terpenoids); the Australian Blue Mountains take their name from the haze.’

    wiki

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    • #
      TedM

      el gordo: I have never seen the blue haze in the blue mountains, but have seen it twice on hot days in the cooler SW of WA, when I was working in a fire surveillance role. It was one of the most beautiful things I have ever seen.

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      toorightmate

      What is it that provides the beautiful purple haze in the Pilbara>

      00

  • #
    TedM

    Tall forest trees red tingle (eucalyptus jacksonii) and karri (eucalyptus diversicolour) typically transpire 200 litres of water on a hot summers day.

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    robert rosicka

    Eucalypts can also shed limbs to conserve water which is why all the trees in my yard became firewood .
    I seen a report a few years ago about a researcher who was looking into Eucalypt die off ,in certain areas the trees were dying and dead over a wide area and it was thought that climate change was the cause .
    After many years of research and field work this scientist was shocked to find the Bellbird was eating a parasite that grew on the leaves and to make more food the bird spread the parasite from tree to tree sort of like farming .
    The parasite would eventually kill off the leaves in turn killing the trees , nature is amazing .

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    • #
      David-of-Cooyal-in-Oz

      Thanks for that Robert,
      I’ve not heard that before. Do you have a reference or any pointer to more detail, please? Even a memory of where the work was done?
      On my trip (of about 25kms) into town over the last couple of years I’ve seen some eucalypts die, particulary alongside the road. That made me think of the widespread dieback in the northern tablelands of NSW back in the 1970s (I think). But I never heard an explanation at the time. And I’m not aware of any bell birds close to me now.
      Cheers,
      Dave B

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      • #
        beowulf

        The dieback in the New England district of NSW was mostly in the mid 80s to early 90s. Dieback was the flavour of the month back then. It was found to be due to a complex assortment of natural causes all impacting simultaneously. There was no single cause. I used to drive the NE Highway back in the 80s and there was mile after mile of dead and dying trees along the road between Tamworth and Glen Innes. There was much gnashing of teeth at the time and predictions of doom about native forests, which proved to be garbage. Forests come and go and come again. Don’t panic.

        One book on the subject dating from 1986 was “DIEBACK – Death of an Australian Landscape” by Heatwole and Lowman, published by Reed Books. It is not definitive because it was written before a fuller understanding of the issues was available, but it does give an overview. I think you would have to look back to the 90s for any research on eucalypt dieback. It has gone out of fashion since then.

        With regard to Bell Miners, they are an aggressive bird that moves in packs and it was found they were not so much farming the psyllids they derive a sugary feed from as chasing away the birds that actually preyed on the psyllids and kept them in check, hence the outbreak of psyllids. What caused the initial spike in bellbird numbers is another question.

        Of more concern is the spread of Cinnamon Fungus to members of the Proteaceae family (banksias, grevilleas, waratahs etc), although it seems to have died away too. Eucalypts are Myrtaceae.

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    • #
      Annie

      A lot of eucalypts locally look really bad at present. Apparently it is to do with a bad lerp infestation and the trees have lost a lot of leaves. So there is more dead leaf litter to add to the fire hazards. However, I remember seeing them like this some years ago and thought they were dying but they all recovered. I can’t remember which year, whether before or after the 2009 fires; these are trees that weren’t burnt.

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      • #
        Annie

        We don’t hear bellbirds much around here, just a single chime once in a, dare I say it, blue moon.

        20

        • #
          Kinky Keith

          There’s a little nook at Merewether that seems to have have had Belllbird chimes every time I’ve driven past.

          20

    • #
      Hanrahan

      There was a naturalist who used to do talk back on ABC radio, maybe only in Qld but he was enthusiastic and to him, nothing was a pest, even possums. Like Erwin but less crazy and like Erwin died young.

      He explained the mistletoe killing trees near highways was because of the road-kill limiting the possum numbers which enjoy the M fruit.

      10

      • #
        Annie

        That’s very interesting. There is lots of mistletoe on the trees along the highway here and some on red ironbark on our place too. It seems to be an aggressive type of growth.

        00

  • #

    Oh, the gumanity!

    When the whole continent got baked back in 1902 and even Kidman couldn’t make a quid, the eucs kept powering. It’s what they do. They’re not calendulas or aspidistras. They’re gums, okay?

    As for pure heat, since the eucalypts survived the Holocene Transgression just a few thousand years back it’s a pretty safe bet they can handle a bit more heat now, if it should come.

    But maybe our Green Betters have become neo-creationists, insisting the gums materialised less than four thousand years ago?

    10

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    yarpos

    Trees survive, who would have thunk? thats probably why, when you look around, there are lots of them. They will get in trouble if they keep doing reserach that aligns with reality, no grants for them!

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    • #
      Another Ian

      Y

      Can’t possibly be so. According to the Qld vegetation management act if you wave a steel chain and two dozers across the landscape you have an instant treeless region

      /s just in case.

      Regrowth management would be much easier if it were just so.

      30

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    OriginalSteve

    Jo, I think your one tag line sums up the whole CAGW nonsense:

    “The models didn’t predict this”

    Like pretty much everything else in the witch-doctoring that is also known as climate science….

    90

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    • #
      PeterS

      The idea that Bill Nye, who believes that man is responsible for the mythical runaway global warming catastrophe, is tacitly endorsing climate denial only proves he’s either a comedian or schizophrenic, or very likley both.

      50

  • #
    Another Ian

    “Recycled science: Reflective surfaces alleviate heatwaves”

    Plus somewhat O/T in comments – this and subsequent comments at

    https://wattsupwiththat.com/2018/01/30/recycled-science-reflective-surfaces-alleviate-heatwaves/#comment-2730478

    on green aviation fuels

    10

  • #
    Greg in NZ

    OK, so gum trees can handle the heat: can they handle sub-zero, freezing temperatures AND snow in January? Mt Mawson’s webcam (Tasmania) is showing minus 0.8˚C at 0700 this morning with FRESHLY FALLEN SNOW on the ground. Next stop, New Zealand’s mountainous Southern Alps, where SNOW is expected from tonight, 31 Jan, through the first two days of February – during our so-called high summer heat wave.

    Anyone familiar with the mountains of N.Z. knows it can snow anytime, any month, anywhere. For the 97 Warmish Cu!t believers, the claim of 2018 being the h•ttest year EVAH may struggle to float as frigid, snowy, cold waves kick-off the first 2 months of the year. What’s the saying: a thorn in their side?

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    • #
      Allen Ford

      The snow gum, Eucalyptus pauciflora, is one such gum that can stand immersion in snow – see here for a picture gallery of same in a variety of snowy and non-snowy situations.

      See also here for a list of other frost-resistant gums, from the Oz National Herbarium site.

      20

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        Hanrahan

        Hi Allan. I looked up ghost gum and got the same answer, Eucalyptus pauciflora. The ghost gums I’m looking are on a hot, barren hillside in Townsville.

        Generally though eucalyptus are a NYMBY tree if you live in the bushfire belt and many shed big branches in a cyclone. Like puppies, they should be chosen with care. :)

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    PeterS

    The models didn’t predict this

    As usual models rarely predict anything even close to the truth. Only those that have been tested and verified, such as Einstein’s theory of general relativity can be trusted. Unless a model can be tested and verified, it belongs in the rubbish bin. The problem though is many such nonsense models are being taught at schools as though they are fact but are anything but, including climate change models.

    50

    • #
      Allen Ford

      It’s not only models that can be wide of the truth mark, but also florid, imaginative, evidence-free conjectures of one sort or another, like climate pontifications!

      30

  • #
    Extreme Hiatus

    “scientists had underestimated gum trees’ resilience but over-estimated their carbon fixing capacity”

    Funny. Since the whole CAGW propaganda machine now calls CO2 ‘carbon’ to make things sound worse, there’s no doubt they have overestimated “their carbon fixing capacity.”

    They have a “carbon fixation,” an obsessive-compulsion disorder caused by way too much funding.

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    John F. Hultquist

    As the trees transpired more, they also stopped photosynthesising — they shut down in a survival mode. This breaks a pretty long standing biology rule,…

    Grape growers have used fine-spray during hot days to lower temperature to counteract this.
    I first saw this about 1970, but it was not new then.

    00

  • #
    Peter Wilson

    “We now know that rule breaks under extreme heat when trees take a sauna-break, stop working, and just … sweat”

    I kind of think we knew that already. This is largely due to photorespiration, in which an O2 molecule replaces the CO2 molecule at high temperatures, wasting a rubisco molecule and frustrating photosynthesis. Greenhouse operators know nothing grows much over 30C for this reason.

    00

  • #
    Frederick Bennett

    To be clear, this study is for one species, Eucalyptus parramattensis. It would be a bit ambitious to generalise this result. Extreme temperature and prolonged drought has previously been implicated as drivers of forest mortality as the paper states (see Allen et al. “On underestimation of global vulnerability to tree mortality and forest die-off from hotter drought in the Anthropocene”. Ecosphere, 6, 129 for example).
    The fact that standard leaf phtosynthetic models were able to robustly simulate the tree parameters in the control conditions but not in the heatwave conditions may be significant.

    0.13C decadal trend is the UAH lower troposphere anomaly, possible a bit more relevant to talk in terms of surface temperature trends in this case.

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    duncanm

    The lone gum in the Simpson desert is doing just fine.

    00