How plants are working hard for the planet

Since the beginning of the industrial era, photosynthesis has increased in nearly constant proportion to the rise in atmospheric CO2

James Cook University

As the planet warms, plants are working to slow the effect of human-caused climate change – and research published today in Trends in Plant Science has assessed how plants are responding to increasing carbon dioxide (CO2).

“We know that terrestrial plants are currently absorbing more CO2 than is released into the atmosphere through the combination of fire, decomposition, plant respiration, and human-related emissions,” lead researcher Lucas Cernusak said.

“This is commonly known as the land carbon sink, and we know it’s currently slowing the rate at which atmospheric CO2 is increasing. What we don’t know is how strong that response is, and how long we can count on it.”

Associate Professor Cernusak, a terrestrial ecologist at James Cook University in Cairns, Australia, worked with colleagues from CSIRO Oceans and Atmosphere in Canberra and the Université de Lorraine in France to measure the strength of the terrestrial biosphere’s response to increasing CO2.

They focussed on photosynthesis – the process in which plants capture energy from the sun and use it to synthesize carbohydrates from CO2 and water – and examined terrestrial gross primary productivity (GPP), a measure of global photosynthesis.

Their modelling and analysis revealed that, since the beginning of the industrial era, photosynthesis has increased in nearly constant proportion to the rise in atmospheric CO2.

“We expected the two would corelate, since CO2 stimulates photosynthesis, but given the complexity of plant and environmental interactions we were impressed by how closely they have kept pace,” Associate Professor Cernusak said.

“We can say that plants are working hard – the response is at the highest end of the expected range.”

The researchers used a combination of existing analyses and new modelling, alongside laboratory studies, to examine how increased CO2 affects photosynthesis, from individual leaves up to a global scale.

“This is an important step forward in the long and complex task of gauging how terrestrial vegetation will respond to climate change in the longer term,” Associate Professor Cernusak said.

While increased CO2 has allowed an increase in photosynthesis and global leaf area, the researchers warn that further climate change – with increasing frequency of events such as heat waves, droughts and storms – has the potential to significantly stress terrestrial vegetation and decrease production.

“It’s also important to remember that global change will manifest differently in different regions,” Professor Cernusak said.

“Our observations and modeling analyses suggest that in high latitude ecosystems it’s global warming that is driving the increase in leaf area and growing-season length.

“That’s quite different from the tropics, where our study indicates that CO2 fertilization is driving the growth in photosynthesis, while climbing temperatures can create significant stress for some plant species.”

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From EurekAlert!

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66 thoughts on “How plants are working hard for the planet

    • Mike – I read this quite differently:

      Below is the Key Statement which states that Human-related CO2 emissions are Not Causing any Increase in Atmospheric CO2 levels – Because all and more of this CO2 is being taken up by plants. Taken at face value it wholly disproves the IPCC statement of any human ‘fingerprint’ on global temperatures.

      That would lead to the conclusion that any global temperature changes are Natural and the slight increase in CO2 levels comes from natural temperature increase which causes some out-gassing of dissolved CO2 from oceans.

      ” “We know that terrestrial plants are currently absorbing more CO2 than is released into the atmosphere through the combination of fire, decomposition, plant respiration, and human-related emissions,” lead researcher Lucas Cernusak said.”

      As an aside JCU may find it harder to get ‘climate funding’ with conclusions like this !

      • More CO2 in the atmosphere due to humans emitting more fossil fuel exhaust is not evidence of a human fingerprint on global temperatures. There’s no evidence more CO2 causes climate warming. There’s more than one way ‘greenhouse gas’ effects on the atmosphere can be modeled. No physical evidence, nor observations point to the IPCC greenhouse gas effect model being any better than my Aunt Sally’s, nor Ferenc Miskolczi‘s.

        • Mark, totally agree.
          But If – and it’s a very big If – temperatures are rising, and JMA raw data shows a 30 year cooling trend, and All of the CO2 emitted by mankind is being absorbed by plants then it can’t be having an effect on temperature. And that has to apply even if CO2 were able to force temperature upwards.

          And of course we must never forget, and I forget which working group number it was, that the scientific consensus in the draft report was that there was No Identifiable Human Finger Print – it was a rogue individual who changed that around before publication to read that there was a human fingerprint.

          Deception – the Life Blood of “Climate Change”

        • Photosynthesis (CO2 + water + energy (sunlight)) only takes place in (sun)light, producing glucose plus O2. At night, the stored glucose recombines with O2, and is converted back to carbon dioxide, water, plus the energy the plant needs.
          Fortunately for life, plants produce more glucose during the day than it requires at night, providing a path for non-photosynthesizing life to evolve.

          So O2 is released during the day; CO2, at night.

          • Hi jtom,
            so do plants use up more Co2 during the day photosynthesis than they enit duirng the night during respiration ?
            ( Currently having a big debate on this with a friend so thought you may be able to help )

    • It is certainly not all models, and the observations of CO2 growth and plant growth are observations.

      Where it gets interesting is here;
      “Our observations and modeling analyses suggest that in high latitude ecosystems it’s global warming that is driving the increase in leaf area and growing-season length.”

      ( As CO2 is well mixed there is no reason to think it is not the combination of warming, particularly night warming and less frosts, and CO2 stimulation)

      “That’s quite different from the tropics, where our study indicates that CO2 fertilization is driving the growth in photosynthesis, while climbing temperatures can create significant stress for some plant species.”

      This appears to be contradictory, as in observations show increased plant growth in the tropics as well, but higher temperatures COULD or are capable of creating significant stress for SOME plants. So the observations are good for both high and low latitudes, but models suggest there could be problems. AFAIK the tropics have barely warmed at all, so perhaps that is why they attribute the increased bio-mass growth to CO2 there. Yet thousands of studies show that increased CO2 results in increased growth for plants in all latitudes plants grow.

      • I think their point is that the growing season is getting longer in higher latitudes and this has a bigger impact on how much CO2 plants fix than the increased rate of photosynthesis in the tropics. This makes sense as there is a minimum temperature for most plants to begin growing and in the tropics it never gets that cold.

        They are trying to stay on track with the alarmists by speculating on high temperature stress in the tropics, but gloss over the absolute low temperature stress experienced by plants in higher latitudes!

      • First, the plants are not working to bring down our emissions. They are doing their business of fixing CO2 and growing, thus increasing our food sources.

        As the planet is not warming, increased growth in the higher latitudes cannot be from Increased CO2. It is indeed true that higher CO2 makes plants more tolerant of both high and low temperatures, thus extending their growth temperature range. Plants can get going earlier in the Spring, grow more after sundown during the summer and enjoy the daytime highs.

        In addition, such plants are more efficient with suing nutrients and, have lower numbers of stomata, they are more efficient with their water, with less transpiration during the day.

        There is no downside to CO2. The article above indicates rightly what plants are doing, but involving global warming was the fatal error for their discussion. As we are cooling, being more heat tolerant is not a problem..

        • Charles Higley

          As the planet is not warming, increased growth in the higher latitudes cannot be from Increased CO2.

          Should that not be: “As the planet is not warming significantly, increased growth in the higher latitudes cannot be only from increased temperature, but instead, is primarily due to increased CO2”.

  1. If ‘plants are working hard’ won’t they eventually collapse from exhaustion?
    THEM we’ll see how bad the CO2 really is! A virtual amphetamine epidemic for plants, sob.

  2. “That’s quite different from the tropics, where our study indicates that CO2 fertilization is driving the growth in photosynthesis, while climbing temperatures can create significant stress for some plant species.”
    Translation: we don’t want to upset Sandra Harding or the Provost, or we might be in trouble like Peter Ridd. Sandra thinks the Snow Possum up in the higher reaches of the Daintree Rainforest ought to be a poster animal for “climate change”. It is very difficult to check on their numbers.
    And the temperatures here haven’t been climbing.

    • In general the tropics have barely warmed at all, so it must be the CO2.

      AS to the harms the “can” occur, that is likely model based, and not observed. As usual with CAGW, the benefits of CO2 are real world, and the harms theoretical.

      There reluctance to credit CO2 for bio-mass growth in high latitudes reflects badly on their work.

  3. Just as I thought. The increase in CO2 cannot be attributed to humans. More likely, the general warming of the oceans in the 20th century is responsible.

  4. Plants – working hard?

    Plants don’t ‘work’ they respond. They have no concept of ‘work’. They take advantage of the prevailing conditions.

    Plants are, in fact, incredibly selfish. They don’t give a monkeys about anything but themselves.

    This is a feeble attempt to humanise vegetation, to suggest we can ‘work with’ it to ‘combat climate change’.

    • That’s why since plants evolved to cover most of the land surface the CO2 content of the atmosphere has been in decline with occasional short duration recoveries.

    • HotScot, if plants are not capable of working hard, they are also not capable of being selfish.

      Just sayin.

    • My trees are always goofing off, dancing in the wind. They don’t listen to me at all and in the fall they not only threaten, but they do leaf me.

      [The mods ask, wood the trees knot also threaten you by their fall each spring, fall, summer and winter, as well? .mod]

    • HotScot: Plants don’t ‘work’ they respond.

      Are you saying that no work occurs? Physically, squeezing carbon molecules with others into tight molecules with high bond strengths, after first breaking the C-O bonds in CO2, is certainly work. Since the work is occurring in plants, there is no harm to the language or to science in saying that the plants are working.

  5. ”“We know that terrestrial plants are currently absorbing more CO2 than is released into the atmosphere through the combination of fire, decomposition, plant respiration, and human-related emissions,” lead researcher Lucas Cernusak said.”

    Am I reading that correctly?
    Can we all go home now?

    • No, it’s just that he’s implying that there are more sources of CO2 than “fire, decomposition, plant respiration, and human-related emissions”.

      It’s kinda like when YHVH is giving Moses the first of the Fifteen Commandments, and He says (I paraphrase) “You will have no other gods before me.” Which is a DIRECT implication that there ARE other gods, and we’d better stay the heck away from them, OR ELSE.

      How else can you take a statement like that?

      • If you read further, there are many references where he states, “I am the one TRUE God. “
        No implication there. He clearly says the other Gods are false, thus the Commandment.

        • 2Kings 3:27 Then he took his oldest son that should have reigned in his stead, and offered him for a burnt offering on the wall. And there was great indignation against Israel: and they departed from him, and returned to their own land.

          The Moabite king knew how to scare of the attacking Israelites. –AGF

    • The statement concludes that anthropogenic carbon dioxide emissions have been progressive, so warming under the CAGW hypothesis cannot be reasonably attributed to human activities, and the so-called “greenhouse” effect characterized in isolation is less effective in the wild than preconceived.

  6. James Cook University

    “As the planet warms, plants are working to slow the effect of human-caused climate change…..”

    First sentence, first fail, James Cook University. Sounds too much like anthropomorphism to me. I guess being clubbed on the head on a remote Pacific Island didn’t work out so well for your faculty.

    The plants are merely growing more vigorously in response to the increased CO2 accompanied by mild warming, not wilfully trying to change it. They are, after all, just plants, doing what plants do.

    • Anthropomorphism works on lots of people to motivate changes in thinking/behaving towards animals/plants/rocks/etc & this is well known by activists, especially those with shaky science basis for their arguments. So off they go with plants even “working hard” – goal directed rather than responding to increased stimuli – just like people, some anyway….

  7. A terrestrial ecologist, hmm … as distinct from an extra-terrestrial ecologist perhaps?

    But then who can take anything from the disgraced Jame Cook University of Truth Suppression at face value anymore.

    Doubtless the first order of business every Monday morning at this climate prostitute academy is a meeting to decide what grandiose title each person is going to have for the following week. Everyone must all titles, the more impressive the better…

  8. … further climate change – with increasing frequency of events such as heat waves, droughts and storms – has the potential to significantly stress terrestrial vegetation and decrease production.

    That’s an admission that nothing bad has happened yet. Everything else is pure speculation. Anyway, those farther down the alarmist ladder will state the above speculation with absolute certainty.

  9. Plants again? Are these brilliant researching types going to blame plants for not soaking up enough junk from the air, soil and water?

    Plants are far more resilient than they get credit for. They are just “things” to researchers, not living creatures. M. Night Shyamalan’s silly movie about plants rebelling against humans by infecting them with a suicide virus was a hoot, but — well, plants do communicate through scent and pollen and other forms of biochemistry.

    Frankly, I do not believe those researchers have a clue to the real purpose of plants. We’re only here to feed them. Once we die, we are fertilizer. Excuse me, my geraniums are calling.

  10. I worry that the plants will unionize. and go on strike for higher pay and better working conditions. I mean, sure, the scabs (weeds) may continue working, but is that what we really want?

    • I sense the phytoplankton are stirring up all this labour unrest in cahoots with the weeds and the leaves shouldn’t fall for it.

  11. The earth has lost 90% of its CO2 since the age of the dinosaurs to limestone. The plants are loving the improved level but would still like it 4x higher.

  12. The more CO2 in the atmosphere the more the plants gobble it up hungrily BUT…..climate change.

  13. “While increased CO2 has allowed an increase in photosynthesis and global leaf area, the researchers warn that further climate change – with increasing frequency of events such as heat waves, droughts and storms – has the potential to significantly stress terrestrial vegetation and decrease production.”
    ___________________________________________________

    YES – the potential to significantly stress terrestrial vegetation and decrease production:

    all the leaves are brown in indian summer.

    AND

    NO – further climate change – with increasing frequency of events such as heat waves,

    AND NO2 increasing frequency of events such as heat waves, droughts and storms –

    ___________________________________________________

    What utter drivel.

  14. Wow. I thought I was the only one writing (a couple of occasions on WUWT threads) on the “Great Greening ^тм”. My ‘model’ was 15% increase in forest cover in 30 years, earth tree stock of 3 trillion individual trees, “avg tree” mass growth, assumed similar sequestration in other plant types, plankton and other biota in the sea. My logic was that the terrestrial plant growth was exponential, at least fringing arid areas. I speculated that since the activity is endothermic, it cooled and noted it coincided with the Dreaded Pause. I assumed the ‘cooling’ was equivalent to the dry mass of new plant material equivalent to the energy in equivalent anthracite. I was going to put an article on WUWT but never got around to it.

    It is the only palpable manifestation of climate change and it has been largely ‘that which must not be spoken about.’ Oh, and the dangerous future that one aleays expects, I also forecast “Garden of Eden Earth^тм” after mid century coupled with peak population of ~9B.

  15. A warming world. Lordy. We are supposed to be warming! Which means we are greening up. And will continue to green up until solar incidence angle into the oceans changes with the Earth orbital mechanics back to cold regimes. These cycles will continue as they have done for the past 800,000 years until continental land positions move to a place that sets up something new. Sit back and enjoy the warmth and water. On the down side, warmth and water will not readily be at hand.

  16. “Just because all is good, at least for the plants (forget how important that is for us), it can’t last forever, so when it inevitably goes very very bad it will still be our fault, I have written a computer program that says so,”

  17. Tropical planet response to temperature bears explaining. There are genetics involved in how different plants “respire” in response to solar light intensity (radiation) as a function of temperature.

    In simple terms as temperature goes up in the context of a plant trying to use light radiation there is tendency for the plant to respire more. What this means is that temperature induces the plant to respire more & in this context less plant assimilates get put into productivity products.

    In more precise terms, increased respiration causes more ATP (energy) to be diverted just keeping what the plant tissue/mass functioning. We are talking about functions like ion-gradients, ion uptake, situational mitochondrial electron transport, protein (ex: enzymes) turnover, shunting photosynthesis byproducts (source to sink) & assimilation of nitrogen/sulphur.

    For a plant like rice, average daily maximum temperatures of <29.5 Celsius in the tropics give maximum yield (grain); then by an average daily maximum temperature of 30 Celsius the tropical rice grain yield declines. Selection of rice for tropical niches has some influence – but there has been sparse genetic breeding gains in rice (so far) for improving the efficiency with which it can utilize light radiation [without having internal plant house-keeping functions take away from “yield” & plant go for “stayin’ alive” functions].

    So, yes elevated CO2 make more assimilates – but leaf area & developmental rate are not the only factors in plant physiology. Another example is how high temperature can negatively affect tropical tree pollen (not discussed here).

    I am making no claims what-so-ever to knowing where/what/when/how temperatures are going to be. As for CO2 levels – I am not for human intervening in what is occurring.

    • Regardless, whatever ‘negatives’ are associated with higher than optimal tempertures for plants in the tropics must be mitigated by the more optimal temperatures for plants now experienced in the higher latitudes. Do not fail to consider that there is more land mass at higher latitudes than tropical.

      I suspect, globally, warmer temperatures are to the benefit of plant life by a huge amount.

  18. You are all doing the same thing continually walking straight past the most important climate force on the planet, surface tension.

    • I always thought that plant respiration was driven by a purely mechanical process. As the plant gives off water (in the vapor form?), the (would this be surface tension) tendency of water to stick together pulls more water from the roots in the ground up to the leaves in the sun. It seems this would require little to no energy from the plant to maintain.

      Full disclosure: I never liked biology classes.

    • Surface tension was what in 1700?
      Now, in 2019, surface tension is what?

      I guess I missed your point, RMB.

  19. Marine plants, both fresh water and ocean, photosythsize more CO2 than land plants. Encyclopedia Britannica puts the estimate at around 90% for marine plants and 10% for terrestrial plants–including agricultural.
    That would be a lot of “greening” going on from marine plants which wouldn’t have been noticed even if the split was 50%/50%.

    • Paywalled research is not worthy of the paper it’s written on. Blame scam journals for their money making mob rule.

  20. Considering that commercial glass houses run between 800 and 1100 PPM CO2 for optimum growth I would say we have a long way to go yet .

  21. Well, there are three parameters which affect total photosynthesis on land (oceanic capacity is different) and should thus be evaluated when wishing to estimate capacity for photosynthesis to continue to increase.

    1. Total land area hosting photosynthetic organisms.

    There is huge capacity to restore deadlands, desert margins, deforested areas etc.

    2. Photosynthetic capacity per unit area.

    Obviously, at any latitude or longitude, there is a maximum photosynthetic capacity where soil is optimal, ecosystem is optimal and regenerative capacity is optimum. Whether many areas are remotely close to that is up for debate.

    3. Resilience to destructive shock.

    Floods, fires, hurricanes, pests etc can all transiently reduce photosynthetic capacity in a given area.

    How an area recovers from such shocks, in terms of restored capacity and speed to recovery, has a major impact on ongoing global photosynthetic capacity.

    I suspect there is quite a long way to go before earth reaches its photosynthetic limit, but that is an opinion, not a scientific insight.

  22. Funny that greenhouse growers artificially raise the level of CO2 two to three times that of the ambient CO2 level to get their plants to grow healthier and faster. Doesn’t seem to be stressing them at all. Plants evolved in an era when CO2 was many times higher than the current levels. The paper acknowledges that plants are doing better under increased CO2 but can’t let go of their belief that increased CO2 will eventually harm the environment. Sounds like someone is worried about losing their funding if it is actually proven that CO2 is harmless or that the world is actually cooling.

  23. Nature in the form of plants are the main unknown here in the CO2 conundrum. It’s been known for quite a while that forests (and some quite small forested areas) seasonally affect the local weather patterns and the local climate (see https://www.quantamagazine.org/forests-emerge-as-a-major-overlooked-climate-factor-20181009/ ). But so too does ground hugging scrub plants as Allan Savory shows in his video (see more at https://youtu.be/vpTHi7O66pI ).

    Isn’t nature wonderful, I’m glad it is in control of our climate and not fickle and feckless humans.

  24. Can anyone answer a question for someone who last did biology at school .
    So as far the plant photosynthesis goes, 6 molecules of the gas (CO2) taken from the air by the plant contains 6 atoms of CARBON. The plant then uses sunlight energy and nutrients from the ground to make sugars which contain 6 atoms of CARBON now, but at night during RESPIRATION it then releases the CO 2 X 6 back IN TO AIR.

    So if you 10 had plants, it would still be 10 x 6CO2 MOLECULES (= 60 Carbon atoms) taken in in the day, but then 10 x 6 CO2 MOLECULES ( =60 Carbon atoms) get released at night.
    So where and how do plants help remove CO2 from the air ?
    Anyone .

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