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It may require a complicated computer model to pin down exactly what the effects will be, but it doesn't take any of that to accept the basic premises that lead

It may require a complicated computer model to pin down exactly what the effects will be, but it doesn't take any of that to accept the basic premises that lead to accepting climate change. We know (and have known for over 100 years) that CO2 in the atmosphere slows the escape of heat energy, which means the equilibrium temperature will go up. The specifics of 1 degree or 1.5 or 1.6 are more complicated, but it's really as simple as that. When I was in grade school, we learned that there were 300 PPM of CO2 in the atmosphere, and now they're learning that there are 400 PPM of CO2. It may take some math to figure out how much warmer you'll get, but it's simple enough to realize that if you go outside on a comfortable sunny day, and then put on a blanket, you'll get warmer.

SpicyLemonZest 6y ago
The problematic aspects of climate change aren't its first-order effects. The worst case scenarios involve warming by a couple of degrees Celsius - much smaller than existing variations from day to day or city to city. The only reason we're concerned is that we expect, based on climate modeling, that a worldwide shift of even this relatively small magnitude will have large second order effects.
- delecti 6y ago
  But you're getting into "why is warming bad?", when the issue is people doubting that warming might be an outcome at all.
darawk 6y ago
It isn't actually that simple, though. Adding CO2 to the atmosphere in isolation, with no reaction from the environment will indeed cause warming. But we don't live in a static model. The environment reacts to things in complex ways. It's entirely possible that adding CO2 to the environment could have caused cooling, in equilibrium (by, e.g. increasing tree density in response to the increased fuel, leading to an ultimately cooler climate). It doesn't happen to work out that way, unfortunately, but it was a possibility.
- Pfhreak 6y ago
  Every time I've seen someone suggest that plants could have taken up the load it seems trivial to demonstrate this is not the case. For plants to take up the load, they would need to absorb and retain 30,000,000,000 tons of additional plant matter annually. A pine tree can absorb ~1 ton/year. If you put 100 per acre, and assume the trees are 100% sequestered, you'd need 30,000,000 acres (50,000 sq. miles) of additional pine forest, where none of the material was allowed to decay back into CO2 just to break even. Plants don't generally sequester much of the carbon they capture in their lifetimes naturally. Mostly it's the root matter of the plant that stays sequestered. So, if you wanted the world to take this up without human intervention, you'd have to figure out how to get 30,000,000,000 tons of root matter generated each year.
  - darawk 6y ago
    I agree, but that's beside the point. The point is that the earth is a complex, dynamic suite of feedback loops, where changing one knob does not necessarily lead to the simplistic outcome that it might, if all else were held constant.
- delecti 6y ago
  Without knowing if there were some mechanism that could balance the effect of added CO2, it would indeed be possible for such a thing to exist. Without checking, you couldn't assume it didn't exist, but coming from a place of ignorance, it's not reasonable to assume such a thing does exist. So without making unfounded assumptions, upon learning that CO2 insulates, the reasonable conclusion is that the measurable increase in CO2 (~300 to ~400 PPM) will lead to warming.
  - darawk 6y ago
    There is a vast gulf between "we should assume it would be likely to cause warming, all else equal", which is more or less reasonable, and "We have proven that it would definitely cause warming".
    - 6y ago
kyleee 6y ago
Please take this question in good faith, as I am not a denier, but how do we rule out unknown earth-scale homeostasis mechanisms without a full understanding of the whole system? If you have any links or thoughts I'd appreciate it
- SpicyLemonZest 6y ago
  It's known that there were "greenhouse periods" in the distant past where substantially all the glaciers melted, so whatever homeostasis mechanisms might exist can't be strong enough to prevent that scenario.
- Pfhreak 6y ago
  I think most folks aren't super worried about a Venus-like runaway scenario where the planet starts boiling lead. Instead the concern is that while the planet will reach homeostasis over the long term, in the short term it will cause mass extinctions, destroy coastal communities, disrupt food production, destabilize governments, etc. It's like saying, "Won't a city rebuild after a major disaster?" Yes, of course. New Orleans wasn't completely eradicated by Katrina. But it was also awful. If we had it within our power to avoid a disaster, we should try to avoid it.
- tuatoru 6y ago
  We can look at the geological evidence from past periods when atmospheric CO2 was higher than 280 ppm. And of course that has been done in great detail. The evidence confirms the theory.

SpicyLemonZest 6y ago

The problematic aspects of climate change aren't its first-order effects. The worst case scenarios involve warming by a couple of degrees Celsius - much smaller than existing variations from day to day or city to city. The only reason we're concerned is that we expect, based on climate modeling, that a worldwide shift of even this relatively small magnitude will have large second order effects.

delecti 6y ago
But you're getting into "why is warming bad?", when the issue is people doubting that warming might be an outcome at all.

darawk 6y ago

It isn't actually that simple, though. Adding CO2 to the atmosphere in isolation, with no reaction from the environment will indeed cause warming. But we don't live in a static model. The environment reacts to things in complex ways. It's entirely possible that adding CO2 to the environment could have caused cooling, in equilibrium (by, e.g. increasing tree density in response to the increased fuel, leading to an ultimately cooler climate). It doesn't happen to work out that way, unfortunately, but it was a possibility.

Pfhreak 6y ago
Every time I've seen someone suggest that plants could have taken up the load it seems trivial to demonstrate this is not the case. For plants to take up the load, they would need to absorb and retain 30,000,000,000 tons of additional plant matter annually. A pine tree can absorb ~1 ton/year. If you put 100 per acre, and assume the trees are 100% sequestered, you'd need 30,000,000 acres (50,000 sq. miles) of additional pine forest, where none of the material was allowed to decay back into CO2 just to break even. Plants don't generally sequester much of the carbon they capture in their lifetimes naturally. Mostly it's the root matter of the plant that stays sequestered. So, if you wanted the world to take this up without human intervention, you'd have to figure out how to get 30,000,000,000 tons of root matter generated each year.
- darawk 6y ago
  I agree, but that's beside the point. The point is that the earth is a complex, dynamic suite of feedback loops, where changing one knob does not necessarily lead to the simplistic outcome that it might, if all else were held constant.
delecti 6y ago
Without knowing if there were some mechanism that could balance the effect of added CO2, it would indeed be possible for such a thing to exist. Without checking, you couldn't assume it didn't exist, but coming from a place of ignorance, it's not reasonable to assume such a thing does exist. So without making unfounded assumptions, upon learning that CO2 insulates, the reasonable conclusion is that the measurable increase in CO2 (~300 to ~400 PPM) will lead to warming.
- darawk 6y ago
  There is a vast gulf between "we should assume it would be likely to cause warming, all else equal", which is more or less reasonable, and "We have proven that it would definitely cause warming".
  - 6y ago

kyleee 6y ago

Please take this question in good faith, as I am not a denier, but how do we rule out unknown earth-scale homeostasis mechanisms without a full understanding of the whole system? If you have any links or thoughts I'd appreciate it

SpicyLemonZest 6y ago
It's known that there were "greenhouse periods" in the distant past where substantially all the glaciers melted, so whatever homeostasis mechanisms might exist can't be strong enough to prevent that scenario.
Pfhreak 6y ago
I think most folks aren't super worried about a Venus-like runaway scenario where the planet starts boiling lead. Instead the concern is that while the planet will reach homeostasis over the long term, in the short term it will cause mass extinctions, destroy coastal communities, disrupt food production, destabilize governments, etc. It's like saying, "Won't a city rebuild after a major disaster?" Yes, of course. New Orleans wasn't completely eradicated by Katrina. But it was also awful. If we had it within our power to avoid a disaster, we should try to avoid it.
tuatoru 6y ago
We can look at the geological evidence from past periods when atmospheric CO2 was higher than 280 ppm. And of course that has been done in great detail. The evidence confirms the theory.