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Wow, Table 14.1 is terrifying: > Considering both historical and projected non-CO2 effects reduces the estimated cumulative CO2 budget compatible with any fut

Wow, Table 14.1 is terrifying: > Considering both historical and projected non-CO2 effects reduces the estimated cumulative CO2 budget compatible with any future warming goal, and in the case of 3.6°F (2°C) it reduces the aforementioned estimate to 790 GtC. Given this more comprehensive estimate, limiting the global average temperature increase to below 3.6°F (2°C) means approximately 230 GtC more CO2 could be emitted globally. To illustrate, if one assumes future global emissions follow a pathway consistent with the lower scenario (RCP4.5), this cumulative carbon threshold is exceeded by around 2037, while under the higher scenario (RCP8.5) this occurs by around 2033. To limit the global average temperature increase to 2.7°F (1.5°C), the estimated cumulative CO2 budget is about 590 GtC (assuming linear scaling with the compatible 3.6°F (2°C) budget that also considers non-CO2 effects), meaning only about 30 GtC more of CO2 could be emitted. Further emissions of 30 GtC (in the form of CO2) are projected to occur in the next few years (Table 14.1). Dates by when cumulative carbon emissions (GtC) since 1870 reach amount commensurate with 2.7°F (1.5°C), when accounting for non-CO2 forcings: 66% = 593 GtC 50% = 615 GtC 33% = 675 GtC --------- ---------------- ---------------- --------------- RCP4.5 2019 2021 2027 RCP8.5 2019 2021 2025 By next year, we'll (most likely) have burned through our chance of holding climate change to 1.5°C

jaggederest 8y ago
Yep. We will need significant investment in not just emissions reduction but active negative emissions, on the order of significant percentages of global GDP, for a long time. Think "all of the direct economic benefit of fossil fuels from all of human history but in reverse, plus inefficiency losses, in 1/4 the timespan"
graeme 8y ago
It's rather sobering. It's also my impression that most people who "believe" in climate change haven't near come to grips with the scale and urgency of the problem. I've been thinking of writing an essay along the lines of the world being "default dead". Basically, unless we come up with something to suck carbon from the air and replace our energy use, I believe we're sunk. A lot of people seem to believe that if we just stopped or "reduced" we'd solve the problem. But if we continue for just a few years as normal, then even a total cessation of emissions wouldn't solve our predicament. Reducing, eliminating: these are important things. But, we're basically dead by default, and need to do something more to actually reverse what we emitted.
- deleted 8y ago
  [deleted]
- CalRobert 8y ago
  I was talking to my dad last night and he was saying how important it is to maximize your 401k, etc. and all I could think was "but even I have money it won't effing mean anything when billions of people are starving and you need to defend any means to produce food with force". But hey, you know, reusable grocery bags and telecommuting 1 day a week should do it. I guess. It's like we found the asteroid headed for Earth and decided to pretend it doesn't exist.
  - ramblerouser 8y ago
    Or some rich and powerful people decided to tell you a metior was about to pummel the Earth and you better accept a reduced standard of living while they fly to and from climate conferences in their private jets. If your political beliefs tell you to not save for your retirement because the apocalypse is coming, that should be a serious red flag.
    - jacobwilliamroy 8y ago
      Are you saying that Al Gore's above-average energy consumption (private jets, mansions, etc) invalidates his claims about climate change? Are we meant to infer from his behavior that nobody needs to make any significant changes to their lifestyle?
      - whatshisface 8y ago
        Most people have some faith in scientists and close to zero faith in public figures.
        mrexroad 8y ago
        Does that still hold if you replace “public” with “religious?”
mrock 8y ago
Would you mind linking to the page where we can find that reference? I couldn't find it in Ch14 or by searching. Thank you!
- ForHackernews 8y ago
  Sure thing, here: https://science2017.globalchange.gov/chapter/14/#section-1 https://science2017.globalchange.gov/chapter/14/#section-1
shoo 8y ago
This old 2014 paper from Friedlingstein et al really helped me to understand the idea of global warming in terms of cumulative emissions budgets: http://www.globalcarbonproject.org/global/pdf/Friedlingstein_2014_Persistent%20growth%20of%20CO2%20emissions%20and%20implications%20for%20reaching%20climate%20targets.NatureG.pdf http://www.globalcarbonproject.org/global/pdf/Friedlingstein... Table 1 has estimates of how many years of remaining global emissions we have before we exceed the cumulative emission budgets for various goals of limiting warming to at most +2, +3 or +4 degrees, and different probabilities of success. Note that the Friedlingstein et al paper from 2014 didn't even bother to talk about the possibility of limiting warming to +1.5 degrees C. These estimates of emissions rates for remaining years before our cumulative emissions budget is exceeded are highly optimistic in the sense that they assume annual CO_2-equivalent emissions stop growing, i.e. the rate we are emitting greenhouse gas is held constant to whatever they were in 2014. In comparison, annual greenhouse gas emissions continue to grow: http://www.globalcarbonproject.org/carbonbudget/17/infographics.htm http://www.globalcarbonproject.org/carbonbudget/17/infograph...
avip 8y ago
Why is this report so low-key? Shouldn't climate scientists by now man up and just tell the public in plain English that climate catastrophe is inevitable?
- opportune 8y ago
  They’ve been doing that the entire time, the problem is that “inevitable” has connotations that it’s too late to do anything. Whereas, yes, it’s too late to prevent entirely, but the more action we take now the worse the catastrophe will be
  - hn_throwaway_99 8y ago
    I think a lot of people's problem (or at least mine) is that it's not clear exactly what "catastrophe" means, despite following climate news pretty closely. I've heard some descriptions of "human species ending event", but unless we get complete runaway feedback loops that turn our planet to Venus (which, my understanding is that most scientists find this extremely unlikely), that shouldn't really happen. My understanding is that coastal areas (where most people currently live) are generally fucked, but I don't really have a good understanding of what the difference is between 2C diff and, say, 3C diff. Anyone have links to some good, non-sensational estimates?
    - avip 8y ago
      Look for the comment "Define "immediate"?" by "ForHackernews"
    - graeme 8y ago
      The real short term problem if we get to those levels is migration and war. That will compound any intrinsic environmental stresses, especially if nukes fly. There are several nuclear armed countries in drought zones. That would then probably lead to continued emissions, as any international effort to reduce them would break down, and people would take what advantage they could in a more tooth and nail world.

jaggederest 8y ago

Yep. We will need significant investment in not just emissions reduction but active negative emissions, on the order of significant percentages of global GDP, for a long time. Think "all of the direct economic benefit of fossil fuels from all of human history but in reverse, plus inefficiency losses, in 1/4 the timespan"

graeme 8y ago

It's rather sobering. It's also my impression that most people who "believe" in climate change haven't near come to grips with the scale and urgency of the problem. I've been thinking of writing an essay along the lines of the world being "default dead". Basically, unless we come up with something to suck carbon from the air and replace our energy use, I believe we're sunk. A lot of people seem to believe that if we just stopped or "reduced" we'd solve the problem. But if we continue for just a few years as normal, then even a total cessation of emissions wouldn't solve our predicament. Reducing, eliminating: these are important things. But, we're basically dead by default, and need to do something more to actually reverse what we emitted.

deleted 8y ago
[deleted]
CalRobert 8y ago
I was talking to my dad last night and he was saying how important it is to maximize your 401k, etc. and all I could think was "but even I have money it won't effing mean anything when billions of people are starving and you need to defend any means to produce food with force". But hey, you know, reusable grocery bags and telecommuting 1 day a week should do it. I guess. It's like we found the asteroid headed for Earth and decided to pretend it doesn't exist.
- ramblerouser 8y ago
  Or some rich and powerful people decided to tell you a metior was about to pummel the Earth and you better accept a reduced standard of living while they fly to and from climate conferences in their private jets. If your political beliefs tell you to not save for your retirement because the apocalypse is coming, that should be a serious red flag.
  - jacobwilliamroy 8y ago
    Are you saying that Al Gore's above-average energy consumption (private jets, mansions, etc) invalidates his claims about climate change? Are we meant to infer from his behavior that nobody needs to make any significant changes to their lifestyle?
    - whatshisface 8y ago
      Most people have some faith in scientists and close to zero faith in public figures.
      - mrexroad 8y ago
        Does that still hold if you replace “public” with “religious?”

mrock 8y ago

Would you mind linking to the page where we can find that reference? I couldn't find it in Ch14 or by searching. Thank you!

ForHackernews 8y ago
Sure thing, here: https://science2017.globalchange.gov/chapter/14/#section-1 https://science2017.globalchange.gov/chapter/14/#section-1

shoo 8y ago

This old 2014 paper from Friedlingstein et al really helped me to understand the idea of global warming in terms of cumulative emissions budgets: http://www.globalcarbonproject.org/global/pdf/Friedlingstein_2014_Persistent%20growth%20of%20CO2%20emissions%20and%20implications%20for%20reaching%20climate%20targets.NatureG.pdf http://www.globalcarbonproject.org/global/pdf/Friedlingstein... Table 1 has estimates of how many years of remaining global emissions we have before we exceed the cumulative emission budgets for various goals of limiting warming to at most +2, +3 or +4 degrees, and different probabilities of success. Note that the Friedlingstein et al paper from 2014 didn't even bother to talk about the possibility of limiting warming to +1.5 degrees C. These estimates of emissions rates for remaining years before our cumulative emissions budget is exceeded are highly optimistic in the sense that they assume annual CO_2-equivalent emissions stop growing, i.e. the rate we are emitting greenhouse gas is held constant to whatever they were in 2014. In comparison, annual greenhouse gas emissions continue to grow: http://www.globalcarbonproject.org/carbonbudget/17/infographics.htm http://www.globalcarbonproject.org/carbonbudget/17/infograph...

avip 8y ago

Why is this report so low-key? Shouldn't climate scientists by now man up and just tell the public in plain English that climate catastrophe is inevitable?

opportune 8y ago
They’ve been doing that the entire time, the problem is that “inevitable” has connotations that it’s too late to do anything. Whereas, yes, it’s too late to prevent entirely, but the more action we take now the worse the catastrophe will be
- hn_throwaway_99 8y ago
  I think a lot of people's problem (or at least mine) is that it's not clear exactly what "catastrophe" means, despite following climate news pretty closely. I've heard some descriptions of "human species ending event", but unless we get complete runaway feedback loops that turn our planet to Venus (which, my understanding is that most scientists find this extremely unlikely), that shouldn't really happen. My understanding is that coastal areas (where most people currently live) are generally fucked, but I don't really have a good understanding of what the difference is between 2C diff and, say, 3C diff. Anyone have links to some good, non-sensational estimates?
  - avip 8y ago
    Look for the comment "Define "immediate"?" by "ForHackernews"
  - graeme 8y ago
    The real short term problem if we get to those levels is migration and war. That will compound any intrinsic environmental stresses, especially if nukes fly. There are several nuclear armed countries in drought zones. That would then probably lead to continued emissions, as any international effort to reduce them would break down, and people would take what advantage they could in a more tooth and nail world.