Friday, May 13, 2016

Climate change: The dairy slump

Farmers are whining about the dairy slump driving them to the wall. But there's a positive side: it means 200,000 fewer cows:

The number of dairy cattle in New Zealand has fallen for the first time in about a decade, according to the 2015 Agricultural Production Survey.

Statistics New Zealand says the number of dairy cattle fell to 6.5 million in 2015, which was the first decline after nine years of consecutive increases.


The national dairy herd hit a record high of 6.7 million in 2014.

That means cleaner waterways - but it also means lower greenhouse gas emissions. How much? By my back-of-the-envelope calculations (derived from the numbers in chapter 5 of the 2013 Greenhouse Gas Inventory), every cow emits 2.39 tons of carbon-dioxide equivalent emissions every year. Two hundred thousand fewer cows means roughly 475,000 tons of avoided emissions. Or about 0.6 percent of our total. And that's pretty substantial for a single year.

But now that the toxic, polluting herd is declining, the challenge needs to shift to keeping it down. Local authorities are already experimenting with intensity limits to protect rivers, and we need to go further. Time to cap the number of cows.