By Keith Woodford*
The recent note on methane emissions put out by Parliamentary Commissioner Simon Upton in late August, and underpinned by a contracted research report written by Dr Andy Reisinger from the Government-funded New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC), will change the methane narrative. History will look back at Upton’s note as a fundamental contribution that moved the methane debate towards a logic-based science-informed position.
The key message is that short-lived gases such as methane do need to be considered differently than long-lived gases. That does not mean that they are unimportant. But lumping them together with long-lived carbon dioxide and nitrous oxide has led down false pathways.
Some of us have known for a long time that short and long-lived gases needed to be considered separately, and that the so-called CO2 equivalence notion was not helpful. As I have said previously, methane and CO2 belong in different regulatory baskets. But it needed someone from an authoritative position to take a stand.
Upton has made earlier public forays into the topic of short-lived versus long-lived gases, but he was somewhat tentative in putting those views forward. The recent change is that he is now being authoritative, drawing on the Reisinger Report, in saying these issues need to inform the political debate. The Productivity Commission report of early September 2018 has also now picked up on this, that a single cap for combined greenhouse gases is not appropriate.
Dr Reisinger is advising that methane emissions from New Zealand’s pastoral agriculture have already peaked. However, it seems that the quantities in the atmosphere may not have yet peaked – although they cannot be too far away.
Surprisingly, Reisinger does not estimate when pastoral-sourced methane stocks will start to decline, but he does put forward a notion that will be new to many people, that even after the methane has gone it will still have a warming effect due to changes it has created in ozone levels and stratospheric water vapour.
These indirect effects are more than a little contentious and quantification is still at an early stage. However, by bringing in these indirect effects, Reisinger thinks we will have to reduce methane emissions further to prevent further warming.
By including the indirect effects, Reisinger’s calculations suggest that if we are to have no further warming from pastoral-sourced methane, then we need to reduce our pastoral methane emissions by between 10 and 22 percent on a sliding scale through to 2050. On average that is around 0.5 percent per annum, but with a slightly faster rate in early years.
So, how easy would it be for New Zealand to reduce its pastoral methane by between 10 and 22 percent?
Whereas the dominant narrative has been that there is no magic bullet to reduce the required methane emissions from livestock except by reducing livestock numbers, that narrative has been promoted within a political framework where huge reductions in methane emissions were going to be required.
In contrast, reducing methane emissions by Reisinger’s upper limit of 22 percent does not seem particularly daunting over the more than 30-year time period.
Independent of the methane debate, the Government has determined that New Zealand is going to plant large areas of forestry to soak up atmospheric carbon dioxide. This could mean anything from one to three million hectares of new forest.
The pastoral land that will be lost to forestry will be on the hills, with lower productivity than on the softer country. But it is easy to see, with pastoral agriculture currently being in the order of 12 million hectares, that this will be enough to significantly reduce methane emissions, probably in excess of 10 percent, and maybe considerably more.
It is also reasonable to expect methane emissions to further reduce with increasing animal productivity. This has been the way that we have reduced emission intensity from agriculture in recent years. Put simply, the more productive that animals are, then the less energy has to go into the methane-producing furnace (the rumen) per unit of output.
It’s not easy to achieve increasing productivity from each animal, but consider the increased productivity per animal that we have achieved over the last 20 years with both dairy (more milk per cow) and sheep meat production (higher lambing percentage and heavier lambs). Another 0.5 percent improvement per annum over the next 30 years and we will be well ahead of any zero-warming targets.
It is also insightful to look at the effect of New Zealand’s pastoral-sourced methane on global climate. By Reisinger’s calculations, New Zealand’s pastoral-sourced methane has so far led to global temperatures rising by 0.0013 degrees C above background levels. If methane emissions stabilise where they are now, it would supposedly raise global temperatures by another 0.0002 degrees by 2050.
Those minute numbers help put things in perspective. However, the mantra is that everyone in the world is supposed to do their bit for the greater good, and that includes us.
The contrasting situation of carbon dioxide is that atmospheric levels will inevitably continue building up because it is so long-lived. We would have to reduce carbon dioxide emissions to almost zero to stop those levels building up. So yes, to the extent that climate change is considered a problem, the real enemy is CO2, not pastoral-sourced methane.
As Upton points out, determining targets for methane emissions is a policy decision for Government. Given the huge difficulty in getting to zero carbon dioxide emissions, then the Government could in theory ask agriculture to do even more and reduce methane emissions to a level where future pastoral-sourced methane levels in the atmosphere contribute to global cooling. That perhaps unlikely scenario would truly place agriculture on the moral high ground!
Those of us in agriculture also need to acknowledge that there are issues with nitrous oxide (N2O) that need to be considered. Unlike methane, this gas is long-living. However, whereas the supposed methane problem has largely been considered intractable, for nitrous oxide we do have a number of technologies that can reduce these emissions from manure and soils.
In summary, the societal negativity towards agricultural emissions of greenhouse gases has been influenced by false information by people who have shaped the narrative in line with simplistic understandings of the science. The axis of the debate is now slowly changing.
That is not to say that the debate is over. Indeed, there is a long way to go. To paraphrase a statement from earlier this year by Federated Farmers spokesperson Andrew Hoggard, agricultural leaders will still need to step up to the table because agriculture will still be on the menu.
Currently, the understandings of the science amongst agricultural industry leaders leaves a lot to be desired. The same can be said of key policy makers in Government, none of whom appear to have a strong science background.
It is unfortunate that the overall climate change debate is very much influenced by noble-cause corruption. On both sides, it is easier to shape the so-called facts to fit prior beliefs, than to engage in genuine informed debate, independent of personal and strawman attacks. That is unlikely to change. Already, some have had a crack at Upton from both sides.
*Keith Woodford was Professor of Farm Management and Agribusiness at Lincoln University for 15 years through to 2015. He is now Principal Consultant at AgriFood Systems Ltd. He can be contacted at email@example.com