Friday, November 02, 2018

Climate Change: The opposite conclusion

Another day, and another article full of special pleading from farmers (or their mouthpieces) about how the rest of us should continue to subsidise them on climate change. This one is from National MP Stuart Smith, and takes the usual farmer line that cars, not cows, are the real threat to climate. The "justification" is that methane, produced by cows, is a short-lived greenhouse gas, whereas carbon dioxide, produced by cars, is long-lived, and hangs around forever. Utterly ignored: methane decays into carbon dioxide, so its effectively a long-lived gas anyway, while its warming effect - the thing that does the damage - is significantly higher than that of CO2. Our normal greenhouse maths averages this out over 100 years, during which a ton of methane has 34 times the warming effect of a ton of CO2 (the ETS uses the older estimate of 25 times - another hidden subsidy). If we look at a shorter timescale, the warming effect of 20 years is 86 times that of carbon dioxide (or 72 times in subsidy-maths). If we look at a longer one, its still seven times as bad over 500 years.

In other words, no matter how you look at it, methane is worse for warming than carbon dioxide. But worse, the climate crisis is now, so we no longer have a long-term to average over. We need to reduce warming as quickly as possible, to stop it from shifting the climate and driving destructive storms. And the most effective way of doing that is to target high-GWP gases. The bonus with methane is that because it is short-lived, the short-term effects of reducing it will be so-much greater, and the temperature will be that much faster to return to normal. Meanwhile, a rapid reduction of warming due to methane will give us time for longer-term solutions to deal with long-lived gases.

So, we should draw the opposite conclusion from farmers' special pleading on methane: rather than ignoring it, we should target it. We should target cars too, of course, but if we really want to do something effective, we need to target cows.