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Unforced variations: Nov 2019

Filed under: — group @ 1 November 2019

This month’s open thread.

108 Responses to “Unforced variations: Nov 2019”

  1. 101
    Andrew says:

    #88, Kevin McKinney and #90, MA Rodger

    Thank you for your replies.

    It seems both of you believe that we still have a carbon budget to burn while global warming will not exceed 1.5C above preindustrial by 2035.

    In other words, the global warming rate would magically drop below the current low estimate of 0.2C per decade, and then possibly go negative, and all that in the short span of 15 years, while simultaneously we continue to burn fossil fuels.

    I am wondering how do you reconcile that with this quote again from the same article by Michael E. Mann:

    “Ironically, if the world burns significantly less coal, that would lessen CO2 emissions but also reduce aerosols in the atmosphere that block the sun (such as sulfate particulates), so we would have to limit CO2 to below roughly 405 ppm.”

    Quoting from the WMO, “globally averaged concentrations of carbon dioxide (CO2) reached 407.8 parts per million in 2018”.

    https://public.wmo.int/en/media/press-release/greenhouse-gas-concentrations-atmosphere-reach-yet-another-high

    Also note that both CH4 and N2O atmospheric concentrations have continued to rise and just like CO2, reached record levels in 2018.

    So my question remains: shouldn’t climate scientists begin providing guidance to policymakers to avoid breaching the 2.5C or 3C warming thresholds?

  2. 102
    DP says:

    I notice the NASA/GISS temperature tables haven’t been updated since July. What is the reason and when will they be back up?

    [Response: v3 has been discontinued (see the updates), https://data.giss.nasa.gov/gistemp use the v4 tables instead. i.e. https://data.giss.nasa.gov/gistemp/tabledata_v4/GLB.Ts+dSST.txt – gavin]

  3. 103
    nigelj says:

    https://link.springer.com/article/10.1007%2Fs40641-019-00144-9

    Open access research on carbon cycle feedbacks. Might be of interest.

  4. 104
    mike says:

    https://m.phys.org/news/2019-11-climate-scientists.html
    Nine tipping points now active

    “More than half of the climate tipping points identified a decade ago are now “active”, a group of leading scientists have warned.
    This threatens the loss of the Amazon rainforest and the great ice sheets of Antarctica and Greenland, which are currently undergoing measurable and unprecedented changes much earlier than expected.

    This “cascade” of changes sparked by global warming could threaten the existence of human civilisations.”

    https://www.nature.com/articles/d41586-019-03595-0#ref-CR11

    Headline: Climate tipping points — too risky to bet against

    from the piece: “Some scientists counter that the possibility of global tipping remains highly speculative. It is our position that, given its huge impact and irreversible nature, any serious risk assessment must consider the evidence, however limited our understanding might still be. To err on the side of danger is not a responsible option.

    If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization. No amount of economic cost–benefit analysis is going to help us. We need to change our approach to the climate problem.”

    Enjoy your holiday, don’t travel if you don’t really need to.

    Cheers,

    Mike

  5. 105

    #101, Andrew–

    Sorry, I don’t know what you mean by this:

    It seems both of you believe that we still have a carbon budget to burn while global warming will not exceed 1.5C above preindustrial by 2035.

    As I explained, the concept of carbon budget is time-independent. So no, your summary statement, whatever it means, is not compatible with what “I believe” to be the case.

    Your next question is interesting and complex. To recap, it was this:

    …shouldn’t climate scientists begin providing guidance to policymakers to avoid breaching the 2.5C or 3C warming thresholds?

    I think there is seldom if ever a definitive answer to reasonably complex ‘should’ questions. But I’d come down on the side of “No.” My reasoning would be the classic ‘moral hazard’ argument: while even 2 C remains in play, it would be foolish to give any approval, no matter how tacit, to a less ambitious climate goal.

  6. 106
    Guest says:

    Journal ‘Nature’ retracts ocean-warming study
    https://phys.org/news/2019-09-journal-nature-retracts-ocean-warming.html

  7. 107
    Al Bundy says:

    Andrew: I am wondering how do you reconcile that with this quote again from the same article by Michael E. Mann:

    “Ironically, if the world burns significantly less coal, that would lessen CO2 emissions but also reduce aerosols in the atmosphere that block the sun (such as sulfate particulates), so we would have to limit CO2 to below roughly 405 ppm.”

    AB: Because there is lag in the system. The oceans are NOT in sync with the atmosphere so they WILL draw down CO2. The same can be said, with qualifications, with regard to land systems.

    Of course, some of those lags are seriously harmful (such as permafrost). So, who knows whether there is a carbon budget left? Kind of like the junkie who’s wondering if pushing one more syringe will end it all.

  8. 108
    Andrew says:

    #105, Kevin
    “My reasoning would be the classic ‘moral hazard’ argument…”

    Isn’t the moral imperative for climate scientists to tell things as they are, and try to avoid the worst catastrophe and the most suffering? Isn’t there a clear possibility that we will breach both the 1.5C and 2C warming thresholds defined in the Paris Accords, well before the end of the century?

    The very idea that there is a “carbon budget”, in other words that we can still continue burning fossil fuels, is immoral. It is placing an incredibly heavy economic and social burden on the coming generations to deal with a destabilized, increasingly dangerous global climate system, while a very small minority within this generation continues to enjoy a carbon-intensive luxury lifestyle.

    So I think your “classic ‘moral hazard’ argument” is misguided.

    Also, as Mike Roberts #98 wrote: “It’s pointless to hypothesize that some [human] action could have such and such effect, if that action simply cannot happen in the real world.”

    Emissions are still increasing, so the slope of the emissions curve for us to get to “net zero” by 2050 is becoming increasingly steep – and unrealistic.

    As I wrote before, we are already at or above 1.2C warming above pre-industrial, by whatever baseline you consider to be pre-industrial. Should climate scientists wait another 15 years, until we get to 1.5C warming, to begin providing guidance on 2.5C and 3C warming?

    I think it is a legitimate issue for debate, and a legitimate question every single climate scientist and climate policymaker should ask her/himself.