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Earth

Tropical Rainforests Could Get Too Hot For Photosynthesis, Scientists Warn 249

Using data collected from the International Space Station (ISS), scientists found that a small yet growing percentage of tree leaves in tropical forests are approaching the maximum temperature threshold for leaves to photosynthesize," reports Live Science. If this trend continues, it could spell disaster for Earth's climate systems and biodiversity. The findings have been published in the journal Nature. From the report: The average critical temperature beyond which photosynthetic machinery in tropical trees begins to fail is 116 degrees Fahrenheit (46.7 degrees Celsius). Currently, only 0.01 % of all leaves surpass this critical temperature every year. But scientists warn that air temperature rises of 7.2 F (4 C) could push trees in tropical forests beyond a tipping point and into mass death. "It's concerning from our perspective that you see nonlinear trends. So you heat the air by, let's say, 2, 3 degrees Celsius [3.6 to 5.4 F], and the actual upper temperature of these leaves goes up by 8 degrees [Celsius; 14.4 F]," Christopher Doughty, an associate professor of ecoinformatics at Northern Arizona University, said during a press conference on Monday (Aug. 21). "Even though a small percentage of leaves are currently doing this, our best guess is that a 4 degrees Celsius increase in temperature could cause some serious issues for certain tropical forests." [...]

Plugging these peak temperatures into a mathematical model, the scientists found that an average 7 F (3.9 C) increase in the air temperature surrounding the leaves caused those most exposed to the heat to have their water-carrying stomata closed off by the tree, leading to their deaths. This triggered a cascade effect, increasing the temperature around the remaining leaves and potentially killing them, their branches and the trees in turn. "If you have 10% of the leaves dying, the whole branch is going to be warmer because a critical part of that branch can no longer cool the broader branch. Likewise you can make that assumption across the whole forest when a tree dies," Doughty said.
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Tropical Rainforests Could Get Too Hot For Photosynthesis, Scientists Warn

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  • With the current velocity of world heating the only solution is active geo engineering efforts in the opposite direction. Simply reducing the emissions is not fast enough.
    The problem is that such actions will inevitably be met with fierce opposition and accusations of incompetence, danger, global conspiracies, etc. They will be very likely to end political careers. On the other hand - not doing something can always be portrayed as "being careful" or "there is just not enough support" by the politicians, s
    • by iAmWaySmarterThanYou ( 10095012 ) on Friday August 25, 2023 @05:50AM (#63795492)

      Geo engineering is such a stupid plan that even Hollywood acknowledges it with several movies over the years. The idea that we can actively and consciously "set" the temperature of the planet and not fuck it up is the height of arrogance and true insanity. Humanity has an extremely long track record of fucking shit up and unintended consequences when we play God with Nature and a neatly non existent record of success. But oh it'll be different this time!

      • It is stupid but we are nearly to the point where we try that or die.
        • You base this gloom and doom on what?

          There are 2 things to look at.

          1) the daily weather
          2) predictions of effects based on models

          Daily weather, up to and including hurricanes, giant snow storms, fires, and so on are "shit happens". For example, the hurricane in California? There hasn't been one like that for ~90 years. And the one before that was about 90 years earlier. And.... so having a once a hundred year event happen once a hundred years is a sign of nothing. Shit happens.

          Model predictions: there

      • by KT0100101101010100 ( 7179190 ) on Friday August 25, 2023 @06:36AM (#63795550)

        Well, climate change shows that we *can* set the temperature. Oil extraction *is* an ongoing massive geoengineering project. Yes there are unintended consequences, but we know about them, right?

        We do have success in some sense. We can feed billions of people where every other N2 molecule in our bodies is provided by the Haber-Bosch process for example.

        Did you personally check all of the hundreds of possible geoengineering idea and determined that they are 'insane'? If yes, please elaborate. If you only watched Hollywood movies, maybe better post your conclusions on a movie review site.

        • Every single geo engineering idea is insane. Either they will have insufficient impact or we go back to the historic zero success rate of humans having a successful controlled geo engineering program. For example, go look at China and everywhere else they have tried huge rain seeding programs. They created vast dead unfarmable regions. Go look at every place we have introduced a new species to handle a native species we don't like. Not just animals, either. California has basically no native plant lif

          • I'm absolutely for stopping to put shit in the air. This is very obviously the easiest and cheapest solution.

            But what if it isn't enough or oil&gas manages to delay the stop even more?

            Interesting comment about rain seeding in China. Could you post a link to relevant information?

            • If we get to the point where human activity is clearly destroying the planet and we lack the will to do anything about it for the very short term benefit of petro corporations then nothing else we think of will help anyway. We would not be the first species wiped out for lack of survival fitness and won't be the last. We are not entitled to our survival as a species.

              I typed "china seeding clouds" into Google and got a zillion articles going back at least ten years with no effort. Take your pick. The the

            • by gTsiros ( 205624 )

              Our track record of managing the ecosystem we rely on is abysmal. Our knowledge of it is pitifully poor.

              What gives you the confidence that we will be able to *actively* adjust it without fucking it up even worse and even faster? Do consider that there is no second chance here. An error in this effort could very easily simply end the planet.

              We still do not have the technology to make hair grow on your body at a location where it has stopped growing, something completely insignificant and comparatively trivia

  • Individually we all recognize this is bad but collectively we are incentivized to destroy the planet for a paycheck.
    • by sinij ( 911942 )
      While externalizing costs is a thing, this is not what is happening here. What happening here is a distributed computation of risk analysis and definitive conclusion that such scenario is a B-rated movie plot and not an actual risk.
  • But hey, let's keep on NTF-ing, crypto-coining, Alexa-ing, video doorbell-ing, chatbot-ing, etc. (just read today's Slashdot headlines for a list, we nerds create much of the problem).

    And I hope that you're reading this on your second or third monitor.

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