I haven’t had too much of a chance to think through it, but Brian Easton has put up a interesting post at Pundit which looks at how we should measure and therefore constrain our methane emissions. However my initial impression is that his approach defeats the purpose of trying to reduce the effects of climate change by targeting the short term gases while learning how to deal with the long-term gases we have already emitted.
Anyway, this is Brian’s idea.
The proposed Climate Change Response (Zero Carbon) Amendment Bill treats biogenic methane emissions differently from all other carbon emissions. The latter are to be measured net so that emissions from fossil fuels can be offset by carbon stored in trees. However, methane from livestock is measured gross.
Why make the distinction? Measuring methane net both clarifies what is going on and simplifies how to deal with it. Our problem arises because we are focusing on emissions and not paying sufficient attention to the fact that global warming is the consequence of clouds of gases in the stratosphere which cause the earth’s heat to be retained rather than escaping. Emissions contribute to these clouds. But at the same time molecules in the methane cloud are breaking down.
In effect he is arguing that we should be looking first at constraining what is causing the growth in the greenhouse effect of our methane emissions rather than trying to dial back the total.
Most sectors contributed to the rise but there have been two big ones: energy emissions from fossil fuels, especially from the transport sector, while land-use change and forestry are absorbing less carbon today than thirty years ago. The methane story – gross emissions having hardly changed in the period – has hidden the overall disastrous record of these two sectors.
The consequence of this muddled thinking is that too much of the blame for the New Zealand contribution to global warming is attributed to farmers and insufficient attention has been given to the transport sector which is the number one problem. Forty years ago, livestock was contributing to global warming but it is no longer doing so today.
At the bottom of his post, there are some document links that I’d have to have a read to decide myself one way or another. However the effect of his proposed changes to the bill would be…
As far as the farm sector is concerned, the proposed change replaces an arbitrary target with the feasible one of doing the best the sector can. While it is already in (about) balance as far livestock methane emissions are concerned, any further reduction in them eventually reduces the methane cloud, which reduces global warming. That is obviously beneficial. The proposed change to the legislation in no way inhibits that goal, but treats it in a sensible way.
My biggest disagreement is probably going to be that his proposal provides little incentive for the farming sector to continue to try to dial back their current emissions. Even if he is accurate about the last few decades, he is wrong about the effect of reducing methane emissions contribution to near future climate change in total.
Over the last century in total the effective methane emissions expanded both by changes in land use from woodlands to farms and with the changes in farming practices that shifted to larger numbers of larger ruminants like dairy cows. In effect he is saying that we should ignore that long history.
Now that would be correct if we were talking about CO2 with its colossal residence time in earth’s volatiles, and most of the changes world wide need to be done on that.
However for NZ sharply reducing methane emissions back to the something closer to what they were in my grandfathers day would have a large effect on decreasing the effect of climate change gases over this coming century. We would contribute less temperature rises, less disruptive changes in climatic patterns, less sea level rise, and more time to wean our global civilisation from converting fossil carbon into CO2. And we can do this in the short term effect over the coming century.
CO2 is the real danger, the one that causes many of the mass extinctions that show in our geological history – the kind that kill off top-tier species like ourselves.
But we can’t reduce the level of CO2 we have already pumped into the surface volatiles. Most of that is in the oceans and is going to keep resurfacing for centuries. There currently simply isn’t any viable technology to sequester it.
What we can do, as well as limiting the CO2 that gets emitted in the future, is to reduce the worst short-term gases. And methane is the highest and easiest that we as a nation can do. The same applies to everywhere that there are farms from rice paddies to feedlots.
It will provide breathing room while we figure out and implement the technologies to stop emitting CO2 and maybe sometime in the future come up with some viable ideas to sequester it.