5 ms·

If CO2 levels were this high previously, and temperatures were higher, what caused the CO2 levels to drop?

flukus 10y ago
Natural sequestration that takes many thousands to millions of years.
themgt 10y ago
No offense, because this is complicated stuff and IANA climate scientist - but this is a really serious topic, and I'd really recommend you spend some time studying the basics before posting a bunch of denialist-type stuff online where you may seed doubts to others. I would highly recommend a couple background, approachable videos on the topic from mainstream experts: * 11 min, Glen Peters, climate scientist: https://www.youtube.com/watch?v=529Og_YR0IU https://www.youtube.com/watch?v=529Og_YR0IU * 53 min, Kevin Anderson, climate scientist: https://www.youtube.com/watch?v=ZF1zNpzf8RM https://www.youtube.com/watch?v=ZF1zNpzf8RM To answer your specific question: paleoclimate has varied for many reasons, from solar and ecological changes to ongoing natural processes. CO2 is absorbed by the biosphere - by acidifying oceans, by plants that capture carbon then die and don't decay it all back into the air/water. The problem is this cycle is far too slow and low in capacity in human-relevant periods of time, relative to our present emission levels (or politically achievable fractions thereof). The biosphere is already absorbing about half the CO2 we emit, and there's evidence that share may be dropping as we overload its capacity in myriad ways (see today's permafrost bubble story as an example of a carbon sink turning upside down). Just as a final ironic point - where do you think all the CO2 we're emitting is coming from? From carbon sequestered naturally over millions of years into oil, natural(!) gas and shale/tar sands/etc. The natural processes that put it there are what resulted in the climate we have today. We're literally digging up the carbon that millions of years ago kept the planet warm enough for dinosaurs and pumping it back up into the atmosphere. That climate is the mean to which we will return.
- _red 10y ago
  For the majority of the earths existence, there has been no ice on the poles.
  - BEEdwards 10y ago
    For the majority of the earths existence, there weren't humans either... so yeah, if that's the world you prefer.
  - intended 10y ago
    May HN forgive me for responding to this. For the majority of Solar existence, we have been a ball of incandescent star dust. For the vast majority of earths existence, it has not been supportive to complex life.
  - FullMtlAlcoholc 10y ago
    For the majority of earth's existence, 100% of all current species did not exist. Or do you want to go back to those halcyon days of the preCambrian period
throwaway7312 10y ago
CO2 levels dropped once the temperature did[1]. [1]https://www.liveleak.com/view?i=0e7_1420745413 https://www.liveleak.com/view?i=0e7_1420745413
Oletros 10y ago
The problem is not only the level, it is the rate of change.
CalRobert 10y ago
Why do you ask? In all seriousness, why? Have you not been able to look it up yourself? Will any sort of argument or evidence persuade you? We know two things at this point about your stance. 1) Your gut is a valid data source. 2) You haven't looked up any of the plentiful information on this topic and prefer to ask people here. This suggests that you're asking disingenuously. Please comment on how you will use the information we share with you (perhaps to supersede your gut?) before asking us to spend time constructing sourced, cogent responses.
- snovv_crash 10y ago
  Please don't be confrontational. You don't need to convince this commenter. You need to convince the hundreds of people who will read their comments and decide which stance is more reasonable.
  - intended 10y ago
    This isn't about reasonable. Theres tons of data out there, literally an entire field of work in science. And that entire field of work is regularly debunked and debated with such old adages as - "scientists have an incentive to get grants, so they keep putting out material which the < evil illuminati types > want to hear". And I've seen such arguments on HN. I think there isn't any convincing left to be done, at most link people to sources and if they are motivated they'll cover it themselves. Whats left is collective action.
    - snovv_crash 10y ago
      >This isn't about reasonable. Well then, in the court of public opinion at least, you've already lost. Nobody is going to listen to the hobo screaming about how the government is spying on us in our own houses with our TVs. It doesn't matter if he's right if everyone ignores him, in fact the opposite, since people will associate the argument with screaming hobos. Don't be a scientifically literate screaming hobo. It hurts the cause.
      - 10y ago

Natural sequestration that takes many thousands to millions of years.

No offense, because this is complicated stuff and IANA climate scientist - but this is a really serious topic, and I'd really recommend you spend some time studying the basics before posting a bunch of denialist-type stuff online where you may seed doubts to others. I would highly recommend a couple background, approachable videos on the topic from mainstream experts: * 11 min, Glen Peters, climate scientist: https://www.youtube.com/watch?v=529Og_YR0IU https://www.youtube.com/watch?v=529Og_YR0IU * 53 min, Kevin Anderson, climate scientist: https://www.youtube.com/watch?v=ZF1zNpzf8RM https://www.youtube.com/watch?v=ZF1zNpzf8RM To answer your specific question: paleoclimate has varied for many reasons, from solar and ecological changes to ongoing natural processes. CO2 is absorbed by the biosphere - by acidifying oceans, by plants that capture carbon then die and don't decay it all back into the air/water. The problem is this cycle is far too slow and low in capacity in human-relevant periods of time, relative to our present emission levels (or politically achievable fractions thereof). The biosphere is already absorbing about half the CO2 we emit, and there's evidence that share may be dropping as we overload its capacity in myriad ways (see today's permafrost bubble story as an example of a carbon sink turning upside down). Just as a final ironic point - where do you think all the CO2 we're emitting is coming from? From carbon sequestered naturally over millions of years into oil, natural(!) gas and shale/tar sands/etc. The natural processes that put it there are what resulted in the climate we have today. We're literally digging up the carbon that millions of years ago kept the planet warm enough for dinosaurs and pumping it back up into the atmosphere. That climate is the mean to which we will return.

_red 10y ago
For the majority of the earths existence, there has been no ice on the poles.
- BEEdwards 10y ago
  For the majority of the earths existence, there weren't humans either... so yeah, if that's the world you prefer.
- intended 10y ago
  May HN forgive me for responding to this. For the majority of Solar existence, we have been a ball of incandescent star dust. For the vast majority of earths existence, it has not been supportive to complex life.
- FullMtlAlcoholc 10y ago
  For the majority of earth's existence, 100% of all current species did not exist. Or do you want to go back to those halcyon days of the preCambrian period

throwaway7312 10y ago

CO2 levels dropped once the temperature did[1]. [1]https://www.liveleak.com/view?i=0e7_1420745413 https://www.liveleak.com/view?i=0e7_1420745413

Oletros 10y ago

The problem is not only the level, it is the rate of change.

CalRobert 10y ago

Why do you ask? In all seriousness, why? Have you not been able to look it up yourself? Will any sort of argument or evidence persuade you? We know two things at this point about your stance. 1) Your gut is a valid data source. 2) You haven't looked up any of the plentiful information on this topic and prefer to ask people here. This suggests that you're asking disingenuously. Please comment on how you will use the information we share with you (perhaps to supersede your gut?) before asking us to spend time constructing sourced, cogent responses.

snovv_crash 10y ago
Please don't be confrontational. You don't need to convince this commenter. You need to convince the hundreds of people who will read their comments and decide which stance is more reasonable.
- intended 10y ago
  This isn't about reasonable. Theres tons of data out there, literally an entire field of work in science. And that entire field of work is regularly debunked and debated with such old adages as - "scientists have an incentive to get grants, so they keep putting out material which the < evil illuminati types > want to hear". And I've seen such arguments on HN. I think there isn't any convincing left to be done, at most link people to sources and if they are motivated they'll cover it themselves. Whats left is collective action.
  - snovv_crash 10y ago
    >This isn't about reasonable. Well then, in the court of public opinion at least, you've already lost. Nobody is going to listen to the hobo screaming about how the government is spying on us in our own houses with our TVs. It doesn't matter if he's right if everyone ignores him, in fact the opposite, since people will associate the argument with screaming hobos. Don't be a scientifically literate screaming hobo. It hurts the cause.
    - 10y ago