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And there are many, many such feedback loops, and not all of them linked to methane. For example, as the climate warms there are more and more wildfires, and th

And there are many, many such feedback loops, and not all of them linked to methane. For example, as the climate warms there are more and more wildfires, and those emits tons of carbon as well. Another example is the decrease in CO2 absoption by water as its temperature increases. There are tons of them that have not been modelled (if they even have been envisaged / discovered); mostly because they are very hard to estimate when it comes to their impact. As for your suggestion, I doubt this is even possible; we released millions of year worth of concentrated solar energy in the span of a century (edit: slightly misleading statement, see below). Scrubbing so much carbon from the atmosphere would take huge amounts of energy, and that energy needs to be clean or you're just adding to the issue. And all this needs to be done in a capitalistic system without any direct profit motive - good luck with that. The most "realistic" examples of geoengineering I have read about usually have downsides that end up killing most of us as well (such as a solar shield at L1 to decrease warming - the impact on plant life and as a result, food, would be pretty bad). Meanwhile we're still pretending less than 2C is possible, and even pretending that 2C is survivable as-is without profound changes to our way of lives. That being said, they mention that human CO2 emission have plateau-ed; I'm far from sure that this the case as a lot of it comes from self reporting and those numbers are likely heavily under reported (especially - but not only - from China). It should also be mentioned a lot of this could come from El Nino; but then again climate change is expected to impact that cycle and we may get stronger and/or longer El Nino periods - it may be partly consequence as well.

titzer 9y ago
> we released millions of year of concentrated solar energy This seems like an overestimate of how much energy it would take to do capture and sequestration. The energy density of fossil fuels is nowhere near that high. A gallon of gasoline is ~33kwh of energy, which is about the same amount of energy that falls on a square meter of Earth's surface in about 22 hours. In terms of barrels of oil, with global consumption at 96 million barrels per day, assuming 12hrs of sunlight a day, I calculated 8600km^2 of Earth's surface, or a square about 93km on a side.
- mikeash 9y ago
  I don't think they're talking about total insolation. They're talking about the total amount of energy which gets stored up by the biosphere and kept in long-term forms of storage like oil and coal. I believe what humanity has used so far does account for millions of years of that.
  - duozerk 9y ago
    Indeed. I edited my post accordingly.
- duozerk 9y ago
  Agreed; it's a good way to visualize just how much time was required for the biosphere to produce those fossil fuels but not how much energy would be required to scrub the carbon itself (and I didn't say that, although my statement was a bit misleading - edited). I still think my point stands - scrubbing it from the atmosphere would involve an amount of energy that is unrealistic without deep, deep changes in our society.
- acqq 9y ago
  Oil is not the only fossil fuel we use. Moreover, if some result seems too good to be true, there's big chance there's something missing.
- Retric 9y ago
  The surface of a sphere can't get 12 hours of sunlight a day. It collects light across a circle with same radius as the planet. A = (pi)r^2. The surface of a sphere is A = 4(pi)r^2. Net result on average you get 6 hours of full sunlight equivalent averaged cross a planet. In northern latitudes panels tilt to collect more sunlight, but that means you can't completely cover an area with panels without some of them being in the shadow of another panel. TLDR; you need 2 squares that are each 93km on a side, or one ~131 km on a side assuming 100% efficient panels and energy conversion. At say 20% net efficiency which would be very high that's a square ~300km on a side.
  - 9y ago
koverstreet 9y ago
Solar shield at L1 would have a minimal impact on plant life. You don't need to block much sunlight to counteract warming.

titzer 9y ago

> we released millions of year of concentrated solar energy This seems like an overestimate of how much energy it would take to do capture and sequestration. The energy density of fossil fuels is nowhere near that high. A gallon of gasoline is ~33kwh of energy, which is about the same amount of energy that falls on a square meter of Earth's surface in about 22 hours. In terms of barrels of oil, with global consumption at 96 million barrels per day, assuming 12hrs of sunlight a day, I calculated 8600km^2 of Earth's surface, or a square about 93km on a side.

mikeash 9y ago
I don't think they're talking about total insolation. They're talking about the total amount of energy which gets stored up by the biosphere and kept in long-term forms of storage like oil and coal. I believe what humanity has used so far does account for millions of years of that.
- duozerk 9y ago
  Indeed. I edited my post accordingly.
duozerk 9y ago
Agreed; it's a good way to visualize just how much time was required for the biosphere to produce those fossil fuels but not how much energy would be required to scrub the carbon itself (and I didn't say that, although my statement was a bit misleading - edited). I still think my point stands - scrubbing it from the atmosphere would involve an amount of energy that is unrealistic without deep, deep changes in our society.
acqq 9y ago
Oil is not the only fossil fuel we use. Moreover, if some result seems too good to be true, there's big chance there's something missing.
Retric 9y ago
The surface of a sphere can't get 12 hours of sunlight a day. It collects light across a circle with same radius as the planet. A = (pi)r^2. The surface of a sphere is A = 4(pi)r^2. Net result on average you get 6 hours of full sunlight equivalent averaged cross a planet. In northern latitudes panels tilt to collect more sunlight, but that means you can't completely cover an area with panels without some of them being in the shadow of another panel. TLDR; you need 2 squares that are each 93km on a side, or one ~131 km on a side assuming 100% efficient panels and energy conversion. At say 20% net efficiency which would be very high that's a square ~300km on a side.
- 9y ago

koverstreet 9y ago

Solar shield at L1 would have a minimal impact on plant life. You don't need to block much sunlight to counteract warming.