6 ms·

Yeah, but the truth doesn't appear to be that much better. It doesn't seem likely that it will be 100% fatal, but with runaway climate problems, you're potentia

by ericd 11y ago

Yeah, but the truth doesn't appear to be that much better. It doesn't seem likely that it will be 100% fatal, but with runaway climate problems, you're potentially looking at mass flooding, natural disasters, crop failures and starvation, and potentially the collapse of many societies in the ensuing unrest. It seems likely that it will result in large changes in the makeup of vegetation and wildlife, potentially to the point of mass extinction, if the food chains in the oceans and on land break down. Our social systems are not set up to deal with this kind of event, at all. The planet's ecology will rebound as it always does, but that happens on timescales not very compatible with human lives. Then again, maybe it will happen slowly enough for us and the ecosystem to adapt. I hope that's the case.

leereeves 11y ago
How much of that scenario are actual scientific predictions? Sources?
- shoo 11y ago
  >> It doesn't seem likely that it will be 100% fatal, but with runaway climate problems, you're potentially looking at mass flooding, natural disasters, crop failures and starvation, and potentially the collapse of many societies in the ensuing unrest. It seems likely that it will result in large changes in the makeup of vegetation and wildlife, potentially to the point of mass extinction, if the food chains in the oceans and on land break down. Our social systems are not set up to deal with this kind of event, at all. > How much of that doomsday scenario are actual scientific predictions? Sources? I believe there are a large number of studies looking at individual impacts. E.g. "flooding" / "crop yields in sub saharan Africa" / etc. For studies that look at the grim end of the spectrum (i.e. +4 degrees C global warming or higher), there was a conference in 2007 that considered the consequences of a +4 degrees C world - not a bad place to start reading: http://www.eci.ox.ac.uk/events/4degrees/ http://www.eci.ox.ac.uk/events/4degrees/ Similarly, there are studies regarding mass extinction. Current estimates of species extinction rates are way above what the estimates of "normal" rates are-- this won't all be due to climate change - as a species we are changing a lot more than just the climate (e.g. destroying ecosystems to make way for agriculture, etc). Do a google scholar search for words like "current mass extinction event" and you'll no doubt find many things to read. I am not sure if we are capable of making "actual scientific predictions" regarding the cumulative impact of all these different threads - e.g. "collapse of many societies" / "ensuing unrest". Personally I reckon such things would be fairly plausible and unsurprising consequences of +4 degrees global warming. Pragmatically, we just have to make the best decisions we can now with what information we have available. Certainty is a luxury and is not necessary to make decisions or take action, particularly when we're time constrained, and it takes a while for the consequences of our actions to manifest. Here's an analogy from one of the decks of slides from the 4degrees conference. > We are walking in Florida. > You find you have just been bitten on the hand by a snake. > We did not see the snake. > If it was the deadly carbonblack snake, the bite will kill you in a painful way, unless you cut off your hand within 15 secs. > I have a hatchet. > You have 5 seconds left. > Did you cut off your hand? > > How would a society learn to make such decisions? > > Luckily with climate change we have more than 15 seconds. Without knowing exactly how much more... http://www.eci.ox.ac.uk/events/4degrees/ppt/8-1smith.pdf http://www.eci.ox.ac.uk/events/4degrees/ppt/8-1smith.pdf
- DennisP 11y ago
  A great book on the impacts of climate change is Six Degrees by Mark Lynas, who read 3000 peer-reviewed papers on climate change effects and summarized them, with extensive references. A lot of it is based on what's happened in previous warming periods. The book has six chapters, one for each degree of warming. Ericd's comment is a good description of the effects at three to four degrees, depending on how widespread a collapse he's talking about. That alone underestimates the risk. Many scientists worry that somewhere between 1.5 and 2.5 degrees, positive feedbacks will kick in and take the planet several degrees further even if we stop emissions entirely. Hansen's book Storms of My Grandchildren has a good account of the geological evidence for that.
username223 11y ago
> ... mass flooding, natural disasters, crop failures and starvation, and potentially the collapse of many societies in the ensuing unrest... As I like to think of it, life as a whole and humans in particular have evolved to be amazingly good at not going extinct. But the way nature fixes problems can be exceedingly unpleasant. If 7 billion humans are too many, nuclear war and mass starvation both solve that, but current and future humans would probably prefer other solutions.
prewett 11y ago
I'm unconvinced that we have any idea what a temperature rise will do. We've already had mass flooding, natural disasters, crop failures, starvation, and societal collapses for thousands of years. People apparently survived during the Ice Age, which was quite a bit colder than 4 deg, so I'm guessing the +4 deg is handleable, too. The lush plant growth and large animals of past hot ages makes me think it must be pretty livable. I doubt the food chains in the ocean or land will break down; we've seen plenty of robust food chain in previous hot ages. If the ocean can support huge dinosaurs and giant ammonids in hotter ages, seems like the food chain will do just fine. People might have to move and change their habits, though. And national borders might change or societies collapse if people don't move/change.
- Retric 11y ago
  What I think most people miss, is most people don't live near the equator for a wide range of reasons and most infrastructure can't be moved. Also, there is less sunlight when you move further north so worm does not mean good farmland. Yes, civilization will survive, but it might cost ~20% world GDP which is far more than swapping to non CO2 energy. PS: Just stare at the read line on this map for a little while: https://upload.wikimedia.org/wikipedia/commons/f/f8/World_map_with_equator.jpg https://upload.wikimedia.org/wikipedia/commons/f/f8/World_ma...
  - prewett 11y ago
    Well, warmer in the north means longer growing seasons than at present, so that makes the land capable of growing better crops. Plus, there is less sunlight in the winter, but a lot more sunlight in the summer, which happens to coincide with the growing season. What is the cost of swapping to non-CO2 energy? I don't think that number exists. Also, I'm not entirely convinced that switching to completely non-CO2 energy is even practical at present. Could we provide our energy needs with full solar / wind, even if we were willing to pay the price, given current efficiency and availability of supply? What do we do when it is dark or not windy? I totally don't understand your point about the red line on the map. I was already familiar with the location of the equator, which is what it seems to emphasize. The reason most people don't live at the equator is that most land is not at the equator. A lot of the land there is desert, but that is not the equator's fault. The people that are in the watered parts get all sorts of diverse plants and animals to live in, and yummy tropical fruits. I'll take more of that up north, thanks!

by ericd 11y ago

leereeves 11y ago

How much of that scenario are actual scientific predictions? Sources?

shoo 11y ago
>> It doesn't seem likely that it will be 100% fatal, but with runaway climate problems, you're potentially looking at mass flooding, natural disasters, crop failures and starvation, and potentially the collapse of many societies in the ensuing unrest. It seems likely that it will result in large changes in the makeup of vegetation and wildlife, potentially to the point of mass extinction, if the food chains in the oceans and on land break down. Our social systems are not set up to deal with this kind of event, at all. > How much of that doomsday scenario are actual scientific predictions? Sources? I believe there are a large number of studies looking at individual impacts. E.g. "flooding" / "crop yields in sub saharan Africa" / etc. For studies that look at the grim end of the spectrum (i.e. +4 degrees C global warming or higher), there was a conference in 2007 that considered the consequences of a +4 degrees C world - not a bad place to start reading: http://www.eci.ox.ac.uk/events/4degrees/ http://www.eci.ox.ac.uk/events/4degrees/ Similarly, there are studies regarding mass extinction. Current estimates of species extinction rates are way above what the estimates of "normal" rates are-- this won't all be due to climate change - as a species we are changing a lot more than just the climate (e.g. destroying ecosystems to make way for agriculture, etc). Do a google scholar search for words like "current mass extinction event" and you'll no doubt find many things to read. I am not sure if we are capable of making "actual scientific predictions" regarding the cumulative impact of all these different threads - e.g. "collapse of many societies" / "ensuing unrest". Personally I reckon such things would be fairly plausible and unsurprising consequences of +4 degrees global warming. Pragmatically, we just have to make the best decisions we can now with what information we have available. Certainty is a luxury and is not necessary to make decisions or take action, particularly when we're time constrained, and it takes a while for the consequences of our actions to manifest. Here's an analogy from one of the decks of slides from the 4degrees conference. > We are walking in Florida. > You find you have just been bitten on the hand by a snake. > We did not see the snake. > If it was the deadly carbonblack snake, the bite will kill you in a painful way, unless you cut off your hand within 15 secs. > I have a hatchet. > You have 5 seconds left. > Did you cut off your hand? > > How would a society learn to make such decisions? > > Luckily with climate change we have more than 15 seconds. Without knowing exactly how much more... http://www.eci.ox.ac.uk/events/4degrees/ppt/8-1smith.pdf http://www.eci.ox.ac.uk/events/4degrees/ppt/8-1smith.pdf
DennisP 11y ago
A great book on the impacts of climate change is Six Degrees by Mark Lynas, who read 3000 peer-reviewed papers on climate change effects and summarized them, with extensive references. A lot of it is based on what's happened in previous warming periods. The book has six chapters, one for each degree of warming. Ericd's comment is a good description of the effects at three to four degrees, depending on how widespread a collapse he's talking about. That alone underestimates the risk. Many scientists worry that somewhere between 1.5 and 2.5 degrees, positive feedbacks will kick in and take the planet several degrees further even if we stop emissions entirely. Hansen's book Storms of My Grandchildren has a good account of the geological evidence for that.

username223 11y ago

> ... mass flooding, natural disasters, crop failures and starvation, and potentially the collapse of many societies in the ensuing unrest... As I like to think of it, life as a whole and humans in particular have evolved to be amazingly good at not going extinct. But the way nature fixes problems can be exceedingly unpleasant. If 7 billion humans are too many, nuclear war and mass starvation both solve that, but current and future humans would probably prefer other solutions.

prewett 11y ago

I'm unconvinced that we have any idea what a temperature rise will do. We've already had mass flooding, natural disasters, crop failures, starvation, and societal collapses for thousands of years. People apparently survived during the Ice Age, which was quite a bit colder than 4 deg, so I'm guessing the +4 deg is handleable, too. The lush plant growth and large animals of past hot ages makes me think it must be pretty livable. I doubt the food chains in the ocean or land will break down; we've seen plenty of robust food chain in previous hot ages. If the ocean can support huge dinosaurs and giant ammonids in hotter ages, seems like the food chain will do just fine. People might have to move and change their habits, though. And national borders might change or societies collapse if people don't move/change.

Retric 11y ago
What I think most people miss, is most people don't live near the equator for a wide range of reasons and most infrastructure can't be moved. Also, there is less sunlight when you move further north so worm does not mean good farmland. Yes, civilization will survive, but it might cost ~20% world GDP which is far more than swapping to non CO2 energy. PS: Just stare at the read line on this map for a little while: https://upload.wikimedia.org/wikipedia/commons/f/f8/World_map_with_equator.jpg https://upload.wikimedia.org/wikipedia/commons/f/f8/World_ma...
- prewett 11y ago
  Well, warmer in the north means longer growing seasons than at present, so that makes the land capable of growing better crops. Plus, there is less sunlight in the winter, but a lot more sunlight in the summer, which happens to coincide with the growing season. What is the cost of swapping to non-CO2 energy? I don't think that number exists. Also, I'm not entirely convinced that switching to completely non-CO2 energy is even practical at present. Could we provide our energy needs with full solar / wind, even if we were willing to pay the price, given current efficiency and availability of supply? What do we do when it is dark or not windy? I totally don't understand your point about the red line on the map. I was already familiar with the location of the equator, which is what it seems to emphasize. The reason most people don't live at the equator is that most land is not at the equator. A lot of the land there is desert, but that is not the equator's fault. The people that are in the watered parts get all sorts of diverse plants and animals to live in, and yummy tropical fruits. I'll take more of that up north, thanks!