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That's an incorrect understanding of rainforests, and has me scratching my head at the article. It rains because of Hadley cells. Hadley cells don't disappear

That's an incorrect understanding of rainforests, and has me scratching my head at the article. It rains because of Hadley cells. Hadley cells don't disappear with global warming, so it will still rain a lot in the tropics. Why on Earth would it be "barren?" A few degrees of temperature doesn't matter to plants: as long as there is sunlight and tons of water, they should be fine. Now if Hadley cells widen or shift northward, that could be a problem for the US. But no matter what happens, Hadley cells still have to rise near the equator.

lkrubner 5y ago
No, you're putting too much emphasis on Hadley cells. The air patterns are only one part of a very much more complex cycle. As the poster above you noted, for any given amount of water, the amount going into the air in a particular place is influenced by the density of plants. Plants pull water from underground and help evaporate it in one particular place. The evaporated air can then condense and become rain again. Therefore, very dense masses of plants can increase the rate with which water is pulled from the ground and then evaporate and then condenses into rain and then returns to the ground, starting the cycle over again. Remove the trees and you still have Hadley cells, but you won't have a rainforest anymore, if the density of the plants falls below some threshold -- you won't have as much rain, even though the Hadley cell is still there -- you might have the same amount of water, but the speed at which it evaporates, and therefore becomes rain, will be lessened.
titzer 5y ago
> as long as there is sunlight and tons of water, they should be fine. That's completely ridiculous. Plants don't fit your magical conception of them. Talk to any farmer or someone with a degree in forestry. Every species has its preferred temperate zones, moisture, and sunlight requirements. Heck, a gardner will tell you that. Plants need to be pollinated. The pollinators die, the plants die. Plants don't break down dead plants. Fungus, insects, and herbivores do. Those parts of the ecosystem die, plants die too. Throw in invasive species, pests like bark beetles that won't die in winter, and you can absolutely expect forests to collapse. Everything is connected. It's a system with millions of parts. It's already showing signs of abuse. Collapse is starting. Forests are weakening, tree lines are changing, some whole regions are showing signs they may die off. I've seen it with my own eyes in SW Utah. Biologists see climate change happening everywhere. We're looking at vast loss of biodiversity and collapse of ecosystems as things speed up.
- goatlover 5y ago
  It's ridiculous to think that whole ecosystems will just collapse instead of adapt with the species that are good generalists and can manage a warmer climate and the ongoing impact of humans. Plenty of wildlife manages to live inside cities, including various plants, fungi, insects, birds and mammals. Will it be pristine and as diverse before? No, but it will be what survives, as has always been the case on Earth since life evolved. Some parts of forests and ecosystems will die and other parts will take their place, and some will do even better because it's warmer with more CO2. Not always what we'd like, but nature will be there in one form or another. The current diversity of the world evolved form times of less diversity which came from times of greater diversity and so on for several major and minor extinctions over the past couple billion years, and plenty of upheaval on more local and regional scales. Nature is always changing and adapting. There are always species migrating around and adapting or going extinct.
  - jschwartzi 5y ago
    All of the trees I’ve seen where I live have been damaged either by the current drought or by various bark beetle attacks. All of them. We had to cut down a birch tree that was girdled by bark beetles, and I’m very worried about the mature red cedars on our property surviving the next ten years. You can drive around the city here and count dead or dying trees. Tell me how are they supposed to adapt?
    - goatlover 5y ago
      Maybe they won't? Maybe you will have to plant trees that can live there. The article mentions that while the Amazon could become barren by 2500, the American midwest may be tropical. Guess what kinds of plants would grow there? And crops would grow closer to the poles. So Canada and Russia would grow much of the world's food. That's not ideal, but I'm guessing that 480 years is enough time for humans to adapt. Anyway, there have been several articles on here saying that global plant growth and the number of trees have increased over the past century based on NASA's satellite imagery and counts from 50,000 locations. So while your area may be losing trees, other areas are gaining them. Nature adapts and changes.

lkrubner 5y ago

No, you're putting too much emphasis on Hadley cells. The air patterns are only one part of a very much more complex cycle. As the poster above you noted, for any given amount of water, the amount going into the air in a particular place is influenced by the density of plants. Plants pull water from underground and help evaporate it in one particular place. The evaporated air can then condense and become rain again. Therefore, very dense masses of plants can increase the rate with which water is pulled from the ground and then evaporate and then condenses into rain and then returns to the ground, starting the cycle over again. Remove the trees and you still have Hadley cells, but you won't have a rainforest anymore, if the density of the plants falls below some threshold -- you won't have as much rain, even though the Hadley cell is still there -- you might have the same amount of water, but the speed at which it evaporates, and therefore becomes rain, will be lessened.

titzer 5y ago

> as long as there is sunlight and tons of water, they should be fine. That's completely ridiculous. Plants don't fit your magical conception of them. Talk to any farmer or someone with a degree in forestry. Every species has its preferred temperate zones, moisture, and sunlight requirements. Heck, a gardner will tell you that. Plants need to be pollinated. The pollinators die, the plants die. Plants don't break down dead plants. Fungus, insects, and herbivores do. Those parts of the ecosystem die, plants die too. Throw in invasive species, pests like bark beetles that won't die in winter, and you can absolutely expect forests to collapse. Everything is connected. It's a system with millions of parts. It's already showing signs of abuse. Collapse is starting. Forests are weakening, tree lines are changing, some whole regions are showing signs they may die off. I've seen it with my own eyes in SW Utah. Biologists see climate change happening everywhere. We're looking at vast loss of biodiversity and collapse of ecosystems as things speed up.

goatlover 5y ago
It's ridiculous to think that whole ecosystems will just collapse instead of adapt with the species that are good generalists and can manage a warmer climate and the ongoing impact of humans. Plenty of wildlife manages to live inside cities, including various plants, fungi, insects, birds and mammals. Will it be pristine and as diverse before? No, but it will be what survives, as has always been the case on Earth since life evolved. Some parts of forests and ecosystems will die and other parts will take their place, and some will do even better because it's warmer with more CO2. Not always what we'd like, but nature will be there in one form or another. The current diversity of the world evolved form times of less diversity which came from times of greater diversity and so on for several major and minor extinctions over the past couple billion years, and plenty of upheaval on more local and regional scales. Nature is always changing and adapting. There are always species migrating around and adapting or going extinct.
- jschwartzi 5y ago
  All of the trees I’ve seen where I live have been damaged either by the current drought or by various bark beetle attacks. All of them. We had to cut down a birch tree that was girdled by bark beetles, and I’m very worried about the mature red cedars on our property surviving the next ten years. You can drive around the city here and count dead or dying trees. Tell me how are they supposed to adapt?
  - goatlover 5y ago
    Maybe they won't? Maybe you will have to plant trees that can live there. The article mentions that while the Amazon could become barren by 2500, the American midwest may be tropical. Guess what kinds of plants would grow there? And crops would grow closer to the poles. So Canada and Russia would grow much of the world's food. That's not ideal, but I'm guessing that 480 years is enough time for humans to adapt. Anyway, there have been several articles on here saying that global plant growth and the number of trees have increased over the past century based on NASA's satellite imagery and counts from 50,000 locations. So while your area may be losing trees, other areas are gaining them. Nature adapts and changes.