11 ms·

40 years is kind of nothing in terms of geological time. It's definitely an outlier but trend following has two different schools, that the trend will continue

40 years is kind of nothing in terms of geological time. It's definitely an outlier but trend following has two different schools, that the trend will continue forever, or that the trend will revert to the mean. I'm in the camp that things will revert to mean for things like this, just like how California drought recovered so violently. I guess time will tell.

archgoon 10y ago
What mechanism do you propose would result in an increase in sea ice?
- pfarnsworth 10y ago
  Obviously, humanity is going to curb its use of CO2 and the Earth will start to cool again.
  - flukus 10y ago
    It would still take centuries for the process to begin to reverse.
    - rangibaby 10y ago
      That's not really that long. If you're 20 today that will mean an inhabitable world for your great great great grandchildren. If they're really lucky, they will even be able to see some real animals.
      - flukus 10y ago
        Assuming no mass extinctions or desperate wars in between.
    - pfarnsworth 10y ago
      So we should just give up? That's a stupid attitude to take.
    - deepnet 10y ago
      100,000 years - for Anthropocene CO2 reversal by natural processes. The Paleocene-Eocene Thermal Maximum took 100,000 years to remove the CO2 from the atmosphere naturally.[1] The current situation is directly comparable. Humans have input 1000 Gigatons of CO2 to date and ~1000 Gigaton more by centuries end. Roughly PETM CO2 estimates [1]. The big PETM change came when the Methane Clathydrates at the bottom of the sea started melting. [1] http://www.bbc.co.uk/programmes/b08hpmmf http://www.bbc.co.uk/programmes/b08hpmmf : 35:42 In our time: The Paleocene-Eocene Thermal Maximum, Melvyn Bragg & Guests.
  - deleted 10y ago
    [deleted]
iLoch 10y ago
I'm undecided, but I tend to prefer to err on the side of caution (even if there are economic consequences.) I believe you're referring to this trend? https://en.wikipedia.org/wiki/Temperature_record#/media/File:EPICA_temperature_plot.svg https://en.wikipedia.org/wiki/Temperature_record#/media/File... Edit: If anyone is familiar enough with the science to explain the (in)significance of this graph vs. current trends I'd like to hear an explanation!
- pfarnsworth 10y ago
  I was talking specifically about the graph that OP linked to.
themgt 10y ago
If by "return to the mean" you're talking about the Pliocene[1], the last time CO2 levels were this high, when temperatures were 2-3C higher, ice sheets collapsed and seas were 25m higher, then yes - we're likely returning quite soon to that Pliocene mean, if not beyond! [1]: https://en.wikipedia.org/wiki/Pliocene_climate https://en.wikipedia.org/wiki/Pliocene_climate
- pfarnsworth 10y ago
  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.
tstactplsignore 10y ago
I'm curious about this: what exactly do you think the (paleo)climatologist community thinks about this? Why do you think that the people most knowledgeable about how the climate has changed in the past, and what causes the climate to change, are so worried about the current situation, and what do you know or realize that they don't? I understand these questions seem loaded or accusative, but I'm genuinely trying to understand an outlook that I cannot begin to fathom.
- basurihn 10y ago
  There is no they. The climate science community is not united.
dzdt 10y ago
You have a gut feeling it will revert. Okay, great. But the consequences are on the scale of a significant fraction of the world's GDP as well as a significant fraction of the world population. Should we maybe have someone study it more carefully? So say we find a bunch of smart people to think about the question. Give them the biggest computers money can buy. Have multiple competing teams who double-check each other and get rewarded if they find mistakes in others' work or have new ideas to improve the study. Make it big -- it is important, right? Global. Lots of smart people, lots of the biggest computers. Anything they need to help their work. And after years of their work, when they come back with a report [1], then lets just ignore it and trust your gut instead, right? [1] http://www.ipcc.ch/report/ar5/wg1/mindex.shtml http://www.ipcc.ch/report/ar5/wg1/mindex.shtml
- senorjazz 10y ago
  bravo (although you did make me spit coffee all over my laptop which I am not happy about....)
- pfarnsworth 10y ago
  What are you talking about? You're acting like I dismissed global warming as not existing. I'm just saying that I believe the one year anomaly that we're experiencing will revert back to the mean. Keep your misdirected politics out of my thread, save it for Yahoo Answers.
FullMtlAlcoholc 10y ago
> 40 years is kind of nothing in terms of geological time. True, but if you take that view, that 40 years is a blink of an eye, we could be creating the equivalent of a supervolcano. It's a bad rule of thumb and extremely simplistic to apply the law of large numbers on an extremely complex, dynamic and chaotic system like the earth, it's ecosystem, weather patterns, etc, like the system oscillates back and forth as a pendulum moving in one or two dimensions would. The mean is always in flux and sometimes it is completely obliterated.
sharemywin 10y ago
If human civilization/population is causing the change then reverting to the mean doesn't sound like that great of an outcome.
mikeash 10y ago
> 40 years is kind of nothing in terms of geological time. Right, which is why this stuff is so worrying. Such a huge change in only 40 years is unprecedented. Pointing out the short timescale as a reason not to worry makes no sense.

archgoon 10y ago

What mechanism do you propose would result in an increase in sea ice?

pfarnsworth 10y ago
Obviously, humanity is going to curb its use of CO2 and the Earth will start to cool again.
- flukus 10y ago
  It would still take centuries for the process to begin to reverse.
  - rangibaby 10y ago
    That's not really that long. If you're 20 today that will mean an inhabitable world for your great great great grandchildren. If they're really lucky, they will even be able to see some real animals.
    - flukus 10y ago
      Assuming no mass extinctions or desperate wars in between.
  - pfarnsworth 10y ago
    So we should just give up? That's a stupid attitude to take.
  - deepnet 10y ago
    100,000 years - for Anthropocene CO2 reversal by natural processes. The Paleocene-Eocene Thermal Maximum took 100,000 years to remove the CO2 from the atmosphere naturally.[1] The current situation is directly comparable. Humans have input 1000 Gigatons of CO2 to date and ~1000 Gigaton more by centuries end. Roughly PETM CO2 estimates [1]. The big PETM change came when the Methane Clathydrates at the bottom of the sea started melting. [1] http://www.bbc.co.uk/programmes/b08hpmmf http://www.bbc.co.uk/programmes/b08hpmmf : 35:42 In our time: The Paleocene-Eocene Thermal Maximum, Melvyn Bragg & Guests.
- deleted 10y ago
  [deleted]

iLoch 10y ago

I'm undecided, but I tend to prefer to err on the side of caution (even if there are economic consequences.) I believe you're referring to this trend? https://en.wikipedia.org/wiki/Temperature_record#/media/File:EPICA_temperature_plot.svg https://en.wikipedia.org/wiki/Temperature_record#/media/File... Edit: If anyone is familiar enough with the science to explain the (in)significance of this graph vs. current trends I'd like to hear an explanation!

pfarnsworth 10y ago
I was talking specifically about the graph that OP linked to.

themgt 10y ago

If by "return to the mean" you're talking about the Pliocene[1], the last time CO2 levels were this high, when temperatures were 2-3C higher, ice sheets collapsed and seas were 25m higher, then yes - we're likely returning quite soon to that Pliocene mean, if not beyond! [1]: https://en.wikipedia.org/wiki/Pliocene_climate https://en.wikipedia.org/wiki/Pliocene_climate

pfarnsworth 10y ago
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.

tstactplsignore 10y ago

I'm curious about this: what exactly do you think the (paleo)climatologist community thinks about this? Why do you think that the people most knowledgeable about how the climate has changed in the past, and what causes the climate to change, are so worried about the current situation, and what do you know or realize that they don't? I understand these questions seem loaded or accusative, but I'm genuinely trying to understand an outlook that I cannot begin to fathom.

basurihn 10y ago
There is no they. The climate science community is not united.

dzdt 10y ago

You have a gut feeling it will revert. Okay, great. But the consequences are on the scale of a significant fraction of the world's GDP as well as a significant fraction of the world population. Should we maybe have someone study it more carefully? So say we find a bunch of smart people to think about the question. Give them the biggest computers money can buy. Have multiple competing teams who double-check each other and get rewarded if they find mistakes in others' work or have new ideas to improve the study. Make it big -- it is important, right? Global. Lots of smart people, lots of the biggest computers. Anything they need to help their work. And after years of their work, when they come back with a report [1], then lets just ignore it and trust your gut instead, right? [1] http://www.ipcc.ch/report/ar5/wg1/mindex.shtml http://www.ipcc.ch/report/ar5/wg1/mindex.shtml

senorjazz 10y ago
bravo (although you did make me spit coffee all over my laptop which I am not happy about....)
pfarnsworth 10y ago
What are you talking about? You're acting like I dismissed global warming as not existing. I'm just saying that I believe the one year anomaly that we're experiencing will revert back to the mean. Keep your misdirected politics out of my thread, save it for Yahoo Answers.

FullMtlAlcoholc 10y ago

> 40 years is kind of nothing in terms of geological time. True, but if you take that view, that 40 years is a blink of an eye, we could be creating the equivalent of a supervolcano. It's a bad rule of thumb and extremely simplistic to apply the law of large numbers on an extremely complex, dynamic and chaotic system like the earth, it's ecosystem, weather patterns, etc, like the system oscillates back and forth as a pendulum moving in one or two dimensions would. The mean is always in flux and sometimes it is completely obliterated.

sharemywin 10y ago

If human civilization/population is causing the change then reverting to the mean doesn't sound like that great of an outcome.

mikeash 10y ago

> 40 years is kind of nothing in terms of geological time. Right, which is why this stuff is so worrying. Such a huge change in only 40 years is unprecedented. Pointing out the short timescale as a reason not to worry makes no sense.