A carrot approach that rewards the lowering of methane emissions has the US state of California on track for a 40% cut in the greenhouse gas by 2030, says a leading US academic.
Dr Frank Mitloehner, a professor in the Department of Animal Science at the University California Davis, said he was not sufficiently briefed to comment on New Zealand’s approach of pricing agricultural greenhouse gases to reduce emissions, but said it is human nature to respond positively to a carrot approach rather than a stick or cane.
“I have seen a carrot approach work but I have not seen anywhere in the world where a cane works,” Mitloehner said.
Californian farmers are financially rewarded for reducing or capturing methane.
Dairy farmers contain emissions from their manure systems, which are then put through a process of cleaning and conversion to fuel for use in trucks and buses.
This reward approach has reduced methane emissions from all sectors in California by 30% – well on the way to the state’s goal of a 40% reduction below 1990 levels by 2030.
“With rules and regulations, if people don’t accept them or obey them, what do you do? How do you enforce it?” he asks.
In 2018 California passed a law to reduce methane emissions and Mitloehner said agriculture focused on achieving that through genetics, nutrition, vet care and reproduction.
In 1950 there were 25 million dairy cows in the United States. Today there are 9 million but milk production is 60% higher and the carbon footprint two-thirds lower.
Mitloehner is also advocating a shift in the way methane is calculated, from GWP 100 to GWP*, a metric that more accurately reflects its short lifespan but also methane’s warming affects.
“To accommodate its short lifetime is important,” he said.
Mitloehner said reducing fossil fuel emissions lessens carbon dioxide in the atmosphere but because the gas lasts thousands of years, reducing emissions does not have an instantaneous effect.
Methane lasts about decade in the atmosphere, so reducing methane emissions immediately reduces the effects of warming.
“If we reduce methane we reduce warming. It’s a unique lever that we can pull that others do not have.”
GWP* is scientifically robust and, he said, fits with the aims of the Paris Agreement to reduce anthropogenic atmospheric warming.
Conversely, should methane emissions increase, the impact as measured by the metric is unforgiving.
“GWP* is not a ‘get out of jail free’ card. If there is an increase over time, it makes GWP* three to four times worse than GWP100.”
While developed countries such as NZ and the US need to reduce methane levels, addressing emissions from developing countries like India, which has 300 million dairy cows and milk-producing buffaloes, is more challenging.
During his brief visit to NZ, Mitloehner said he has been impressed with farmer knowledge and understanding about agricultural greenhouse gas emissions and their role.
