Monday, 11 November 2019

Methane emissions from farm animals a 'green herring' in New Zealand

Photograph: Cattle belch monitoring, Moorepark, Ireland 2010

A recent article in The Guardian reports that climate change denial is changing tack from outright denial to a clever 'deflection' campaign.  This focuses on making individuals feel guilty about their food and travel choices, and then descends into 'doomism', which leads to hopelessness and inaction.  In this way, society is misled into failing to deal with the main cause of climate change - fossil fuel use.

Global greenhouse gas (GHG) sources are usually quoted at around 70% from fossil fuel use (energy production), agriculture 24%, industry, buildings and waste disposal the remaining 6%.  

New Zealand's GHG profile is quite different from the global profile, with energy production 41%, agriculture 48% (sourced mainly from animals belching methane), industry and waste 11%.

Recently the issue of methane emissions from farm animals has been controversial in New Zealand. The Agriculture sector has pointed out that methane is a short-lived GHG (about 14 years), while others have countered that it has a high Global Warming Potential (GWP), 25 times stronger than carbon dioxide.  The New Zealand Government has agreed to the sector's proposal to leave agriculture out of the New Zealand Emissions Trading Scheme until 2025, giving the sector until 2022 to come up with methods for reducing farm emissions.  

One way to reduce farm emissions is to reduce the number of animals farmed.  Leaving aside land use stocking and water quality issues, it would seem extraordinary that a food producing nation would be asked to consider reducing its production levels in a world that needs more food, not less.  And this from a pasture-based farming system in New Zealand that has a much lower overall environmental footprint (GHG plus everything else) and animal welfare footprint than barn-based intensive stock feeding regimes overseas.

So are methane emissions from farm animals really a problem locally or globally, compared to fossil fuel emissions?  Take a quick look across the latest science and we find:
  • Globally methane is 16% of all GHG;
  • Methane disappears from the atmosphere in about 14 years;
  • Modelling of methane's global warming effects from 1900 show a small decline relative to carbon dioxide;
  • World methane emissions have increased about 25% from 2005-2018.  This is thought to be from frozen wetlands melting (as the northern hemisphere warms), natural gas production, and livestock, although the global cattle population has increased only 0.6% in that time;
  • Fossil-fuel sourced carbon dioxide is about 80% of all GHG;
  • Carbon dioxide takes 20-200+ years to transit out of the atmosphere;
  • Recent studies show fossil-fuel sourced carbon dioxide is now about 86-87% of global carbon dioxide emissions; 
  • World fossil-fuel sourced carbon dioxide increased 50% from 1990-2015, increases in India (7.2%), Russia (3.5%), China  (2.9%) and the USA (1.5%); and,  
  • Emissions from New Zealand Agriculture 1990-2017 rose 13.5%, due to a near doubling of the dairy herd and 650% increase in use of nitrogen fertiliser. New Zealand's cattle population is about 0.1% of the global cattle population. 

There are some significant changes to note:

(1) Fossil-fuel sourced carbon dioxide sources have increased to 87% of global carbon emissions in the last ten years, so that they almost completely dominate the global GHG cycle;
(2) Global methane emissions over time have had no impact compared to fossil-fuel sourced carbon dioxide (so far);
(3) Global methane emissions are recently up from permafrost melting and natural gas production;
(4) Globally, New Zealand's cattle populations and their emissions do not register at all on any statistic; and,
(5) Local increases in New Zealand's dairy herd and their emissions have impact in New Zealand alone.

And so what to conclude?

Methane emissions from pasture-based farm animals are a "green herring" in New Zealand, and most probably globally.  

The reduction and reversal of global warming depends almost entirely upon reducing fossil fuel use.  Switch away from fossil fuels and the job is mostly done.  Reducing animal farming in New Zealand will make absolutely no difference to world GHG levels, and would be a pointless exercise in climate guilt.  Another 'deflection' away from dealing with the real problem.

Because of the structure of the Paris Climate Agreement and New Zealand's unusual GHG profile, the nation could be held fiscally responsible for methane emissions that are just a very few cattle breaths in reality, with no global impact.  There could, however, be a very high impact on the nation's pocket if the situation isn't shrewdly managed.  

And one wonders...how many more green herrings are out there?






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