Methane needs to be treated differently – Mitloehner

Ask any farmer active on social media, particularly Twitter, and the chances are they will have heard of Prof Frank Mitloehner, an air quality specialist working in the animal science department at UC Davis in California.

German by birth, Mitloehner has become something of a celebrity among farmers right around the world in recent years, because he has been defending livestock farming in the increasingly polarised debate on tackling climate change.

This week, Prof Mitloehner arrived in Dublin to speak at a conference on climate change organised by the IFA.

For many climate activists, the most contentious thing about Prof Mitloehner is his position on methane, especially how it should be accounted for in comparison to other greenhouse gases (GHGs).

CO2 is a one-way street and only goes up and up and up and up

Methane

Speaking to the Irish Farmers Journal, Prof Mitloehner outlined how methane (CH4) has a much shorter lifespan of about 10 years compared to the other GHGs such as CO2 and nitrous oxide (N2O), which last for thousands of years in the earth’s atmosphere.

“Once you put CO2 in the atmosphere it pretty much stays there forever. Every time you drive your car you put new CO2 in the atmosphere. CO2 is a one-way street and only goes up and up and up and up,” said Prof Mitloehner. “But methane is different. While methane is produced, it is also destroyed via a process called hydroxyl oxidation and put away into soils. And that is a very important distinction if we are to properly account for the amount of methane in the atmosphere,” he added.

In essence, Mitloehner is saying ruminant animals such as cattle are part of a biogenic carbon cycle, where plants suck CO2 out of the atmosphere in order to grow and convert this carbon into cellulose (grass), the most abundant biomass in the world.

This cellulose is then eaten by a ruminant animal which converts, or upcycles it into proteins humans can consume (meat and milk). He describes this as a “beautiful process” where carbon is recycled from the atmosphere over and over again, even as methane is emitted from livestock.

While methane is produced, it is also destroyed via a process called hydroxyl oxidation and put away into soils

While ruminants release carbon (methane) into the atmosphere after digesting this cellulose, Mitloehner argues this is recycled carbon and therefore not comparable with the burning of fossil fuels which emits new carbon into that atmosphere.

Mitloehner’s argument boils down to a simple thesis – if the level of livestock remains constant, then livestock do not add to climate change and global warming.

However, the UC Davis professor was very clear that methane is a powerful climate pollutant and that if livestock numbers are rising, it adds significantly to global warming.

“As long as you do not add additional livestock to your herds and keep numbers stable, then farmers are not adding new carbon to the atmosphere. If you do not add extra methane to the atmosphere you do not add additional warming to the atmosphere, meaning constant livestock herds do not add to global warming,” he said.

Expansion

This is a key point from an Irish context, as the national dairy herd in this country has been expanding since the end of dairy quotas. However, the suckler beef herd has been in decline during this same period.

The total cattle herd in Ireland has risen 5%, or almost 300,000 head, since 2014 to reach 6.6m head at the end of last year. Within this, dairy cow numbers have risen 25% since 2014 to 1.4m, while beef cow numbers have fallen almost 10%, or 90,000 head, to just 936,000 head.

And while the total cattle herd has increased in Ireland over recent years, it’s also important to take a global view in terms of future population growth and agricultural efficiency in certain parts of the world.

Mitloehner says a huge number of the cows in the world are highly inefficient, with dairy cows in some countries producing less than 1,000l of milk every year. India has the world’s largest national cattle herd, but cows are not slaughtered for meat because of dietary preferences.

In the US, Mitloehner says the number of dairy cows has fallen from 25m in 1940 to just 9m today, while at the same time milk production has increased 60% to over 90bn litres.

On top of this, the world’s population continues to grow rapidly year after year.

As long as you do not add additional livestock to your herds and keep numbers stable, then farmers are not adding new carbon to the atmosphere

“There are roughly 7.6bn people in the world today. By 2050, there will be almost 10bn people on our planet. That means during my lifetime the human population on our planet will have tripled, but the natural resources to feed these people will not have tripled. We will not have three times more land in 2050, meaning we have to become a whole lot more efficient in how we produce food,” said Mitloehner.

To meet this 2050 challenge of feeding 10bn people, Mitloehner said we need to strategically produce food in parts of the world where it’s most efficient, like Ireland.

“We should produce food in the places of the world where it has the relatively lowest environmental footprint, " said Mitloehner.

“People will leave their home countries because of food insecurity.”

Efficiency

This is a point long argued by farmers when it comes to climate change targets – surely it makes sense to produce food in parts of the world where it is efficient and has the lowest possible impact.

Because Irish agriculture is constrained by the need to meet national carbon emissions targets, it often misses the bigger picture where we produce enough food to feed more than 30m people off a highly efficient grass-based system.

What good will it serve the world in 2050 if Ireland has culled up to 1m cows, only for a number of these animals to be replaced in another part of the world trying to feed a growing world population in a less efficient system.

The earth only has one atmosphere and shifting livestock production from a highly efficient part of the world such as Ireland, to a less efficient part will not help keep global warming below 2°C.