So @jamespeshaw @mfe_news haven’t got a clue what good the #ZeroCarbonBill will do


2 thoughts on “So @jamespeshaw @mfe_news haven’t got a clue what good the #ZeroCarbonBill will do

  1. There is good reason why neither he nor officials in MBIE, PCE, etc want to calculate those numbers: they are easily shown to be absurdly tiny.
    The effect of one emissions unit is roughly independent of any other (with moderate exceptions): the results are additive at any moment in time, although they accumulate non-additively. A 10% reduction in emissions will reduce the temperature increase by about 10% of what it would otherwise have been: it may be hard to calculate the number, but the effect of NZ’s emissions is not hard to estimate as a percentage of the unknown total. One can make more careful assumptions, which change the result a bit, but even if the true number is twice the approximate amount, an approximation is good enough to give us a feel for what we are talking about.
    The approximate calculation is easy. NZ’s net emissions (CO2 equivalent) are about 0.2% of the global total. If we achieve net zero emissions, we will reduce the future global temperature increase by less than 0.2% of what it would otherwise have been. (“Less than” because NZ’s past emissions will not be reversed; but let’s be generous and assume 0.2%.) So by the date when the world would have warmed by 2C above preindustrial temperatures, the Zero Carbon bill (if successful) will reduce that by about 0.2% of 2C, or 0.004C. As a check, Figure 16 of the PCE report cited by James Shaw shows an increase of less than 0.0016C by 2050 caused by NZ’s methane emissions. So 0.004C is not vastly wrong as the temperature rise that will be saved by making NZ carbon neutral.
    To really bring this home, consider how long it will take the world to catch up that 0.004C. That depends on how fast the world will warm as a result of emissions from China, India, USA, Europe and the others who provide the other 99.8% of emissions – and NZ legislation has no effect on what those countries do. But if you think the world will get to 2C by 2050 (30 years from now), getting NZ to carbon neutrality will delay that by about 0.2% of 30 years, or 3 weeks. This number is crude because it does not account for whether the temperature rise is accelerating or decelerating, but it is accurate enough to give a sense of the answer.
    How many billions of dollars should New Zealanders be willing to incur in order to defer global warming by a few weeks? Framed like that, it is no wonder that neither James Shaw nor his officials have not calculated the effect and have no interest in doing do. A back-of-the-envelope calculation shows that the effect of the policy is tiny; a more accurate calculation would simply show exactly how tiny, and the policy-makers do not want to know that.

    Liked by 1 person

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