Climate change and farming in New Zealand

Climate change is creating a double whammy on the farming industry in New Zealand.  On one hand, farmers will bear most of the brunt of extreme weather that is on the way.  How many of us are likely to see our livelihoods literally drown in floods, roasted in heat waves, starved in droughts, fried in wildfires or blown down in cyclones?  This is what scientists predict, and looking at their predictions going back to the 1980s, they’ve been close to spot on, if not perhaps a bit conservative.

On the other hand, farmers are being asked to join the New Zealand emissions trading scheme (ETS) and account for the greenhouse gases methane and nitrous oxide emitted by agriculture.  Methane being from the digestive systems of livestock and nitrous oxide principally from animal waste.  Including these gases in the ETS would require farmers to either reduce these emissions in the coming years or buy carbon credits to cover their emissions above a certain threshold, with that threshold scheduled to gradually decline from year to year.  At best, farmers will have to adapt to new ways of farming and at worst, farming is going to get more expensive relative to competitors overseas who don’t take steps to limit their emissions.  Either way, the farmer’s life is going to get tougher.

The national debate on including methane and nitrous oxide in the ETS and in New Zealand’s zero emissions targets will require tough choices and clear-eyed discussion.  Articles like the recent opinion editorial by Stuart Smith in this newspaper (“Emission impossible: Cars, not cows, the real threat to climate”, 3 November 2018) do not help.  Attempts to shift the blame from agriculture to transport for GHG emissions only hardens opposing positions and delays effective decision making, delays that humanity can ill-afford at this point. 

Here are some facts that need to be considered in this debate:
It is argued that methane is a short-lived pollutant and therefore should be treated differently.  But, “short-lived” is relative.  Methane stays in the atmosphere for an average of 9 years, which, according to the latest IPCC report, is about the time frame humanity has to stabilise greenhouse gas (GHG) emissions in order to avoid the worst impacts of global climate change.  And methane is a much more potent greenhouse gas than CO2, producing 104 times the global warming potential (GWP) of an equivalent weight of CO2 over a 20 year period.  Even over CO2’s average 100 year lifetime in the atmosphere, methane yields 25-32 times the GWP of CO2.  Nitrous oxide is worse still, creating 298 times the GWP of CO2 over a 100 year period, as well as causing depletion of stratospheric ozone, leading to more sun burns and skin cancer.  In short, methane and nitrous oxide are much worse greenhouse gases than CO2, especially when we consider the speed with which we need to act.  CO2 is only the most damaging greenhouse gas emission because there is so much more of it emitted worldwide. 

New Zealand is unique in producing a relatively high proportion of methane and nitrous oxide compared to other countries.  In fact, we have the highest per capita emissions of these gases worldwide.  The Ministry for the Environment website lists agriculture as the source of 49% of New Zealand’s GHG emissions in 2016, compared to 40% from energy and road transport.  This analysis equates the GWP of methane and nitrous oxide to that of CO2 over a 100 year time frame.  If we consider the effects of methane emissions over a shorter time frame, say over the next 20 years, our methane emissions will have several times the warming impact of our CO2 emissions and easily create the lion’s share of our nation’s contribution to global warming today.
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I empathise with those who wish to shield agriculture from the economic cost of limiting GHG emissions.  But it makes no sense to penalise one industry over another for their respective contributions to a global problem.  The best we can do is to help New Zealand agriculture shift to low GHG farming techniques and support the farming science community in pioneering new ways to limit emissions.  We, as a nation, will also need to help NZ agriculture adjust to the severe and unpredictable weather expected to come with continued global warming, which we already see impacting farming overseas.  Of all the sectors of our economy and communities, agriculture will be the hardest hit by the changes expected to come.