Climate change debate

13/08/2012 § 3 Comments

Last week, I was reading a report on the economic impacts of climate change on New Zealand’s agricultural sector. I have written one or two such reports myself and try to keep up with other people’s research. It struck me that there’s a huge difference between these academic or policy documents and the public debate in the popular media.

The academic and policy documents make it very clear that climate change is neither good nor bad for New Zealand. The main variables are temperature, rainfall, and distribution of extreme events. That last variable is difficult to analyse, so it generally comes down to the first two. The impacts are quite different by region. In some areas, a little more warmth and rain make everything grow better. In other areas, reduced rainfall makes farming more difficult.

Climate change researchers try to grapple with this variation with a series of models built on models. The main IPCC climate change scenarios are analysed with global climate models. The modellers feed in a set of assumptions and see what happens to different regions, but these regions are defined fairly broadly. Then, those modellers feed in a new set of assumptions to see what happens.

New Zealand researchers then have to take the international results and downscale them to account for local variations. That’s another set of modelling. The downscale modelling has to choose which internal climate change model and which scenario from that model to use as a basis. For example, a lot of New Zealand work relies on the HadCM3 (Hadley Centre Coupled Model v3) international model, and tends to start with the ‘central’ scenarios as opposed to the extreme ones.

There is also the very important question of how people will adapt. New Zealand is generally temperate and well supplied with water. Other countries are very successful with higher temperatures and less rainfall, so it’s clear that we could make a few changes and still live fairly well.

The economic research is essentially a large number of chained assumptions from scenario to international model to downscaling model to economic model. At each step along the way, we could have informed and thoughtful debates: how we select likely scenarios, which international model is best for New Zealand, how downscaling captures local conditions, how weather affects production, the extent and speed of economic adaptation, etc.

Instead, the popular media seems stuck in a loop. Is climate change happening? Are humans to blame? When will we run out of time?

It’s climate change as soap opera. Which suggests we’ll be seeing the same storylines in another 50 years, just with a new cast of characters.




§ 3 Responses to Climate change debate

  • So very strange that we’re an early mover where effects are a bit of a wash for NZ.

    Not strange at all that the press focuses on conflict. That’s what readers want.

    • Bill says:

      Agreed — I’m not sure why NZ is keen to implement carbon policies when other countries won’t (although the ETS policy around ag suggests we are trying both to do and not to do). The three reasons seem to be
      (a) a marketing advantage — but I think that misunderstand’s NZ’s overseas image
      (b) dynamic potential — but I think that overstates the potential both to develop and to commercialise carbon-friendly technologies
      (c) additional benefit — but if the policies are good for energy efficiency or nitrate management, then those benefits are more likely to be captured directly by NZ and so the policies should stand by themselves.

      • detmackey says:

        Eric’s making some leap from ‘a bit of a wash’ for agriculture to ‘a bit of a wash’ for New Zealand.

        Didn’t we discuss this in an earlier post? What you’re really arguing against is New Zealand paying its liability, not how it pays its liability.

        Whether or not I support paying the liability, I’d favour the ETS as a better way of paying the liability than subsidising agriculture.

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