Dr. Frank Mitloehner:

I agree with everything Professor Allen just said. I recommend using a matrix that is fit for purpose. It is critical to describe the impact of a sector on warming because this is what it is all about. It is not about carbon equivalent emissions; it is about the impact the sector has on warming. We want to stop additional warming and, therefore, need to find tools to get us there.

The Deputy asked what herd sizes have done in the United States over time. There have been significant changes. Back in the 1950s, we had our peak in beef and dairy populations, with 25 million dairy cows in the country. Today, we have 9 million dairy cows. With that much smaller herd, we are producing 60% more milk. The carbon footprint of the dairy sector has shrunk by two thirds in that period. A drastic improvement in performance has led to a drastic reduction in the warming impact of the sector. I stated earlier that the most recent changes in California have been amazing. In the past five years, the California dairy sector has reduced its methane emissions by 30%. That is all metered and validated by the various agencies in the state. It was made possible by the state incentivising rather than penalising methane reductions, working hand in hand with farmers and generating a market approach to financially incentivise reductions in methane. That is a strategy that works. I have compared it with strategies throughout the world - in New Zealand, European countries and so on - but I have yet to find a strategy that has worked better than the one here in California.

The Deputy asked whether there have been spikes in methane emissions. Up until 2006, there was a plateauing of methane in the United States. This went on for some time. In 2006, there was a sudden uptick in methane. We wondered how that could be. We looked at all the different sources of methane, including livestock, rice paddies, fossil fuel and everything else. The cattle herd had not changed. The livestock sector did not suddenly emit far more than it did prior to 2006. We found that it was the onset of fracking - the extraction of fossil fuels using the fracking method - in 2006 that was largely responsible for the spikes that followed.