Why California's carbon manure math doesn’t add up. Let's mooooove on from climate shell games.

Something stinks in California’s climate policies, or at least their calculations. Years ago, the state set up a system that pays cattle farmers across the country to turn methane from cow manure into natural gas. This incentivises dairy farms to produce a gas we burn instead of one that just pollutes.

The dairy program is a case study in our flawed approaches to climate action. Instead of directly cutting pollution or paying for it, legislators opt for convoluted incentive systems that swap responsibilities between parties and regions. These carbon offsetting schemes often dramatically overstate the emissions reductions achieved in the atmosphere.

Despite this, California regulators decided to extend parts of the program beyond 2050, with a recent proposal sending millions more dollars to dairy farmers to ease restrictions on major greenhouse gas producers. The system works like this: the state’s climate regulations require transportation fuels to lower carbon dioxide levels or purchase credits from parties that cut fuel emissions, including cattle farmers.

The problem is in the carbon math. California assumes methane exerts about 25 times the warming effect of CO2 over a 100-year period. In reality, while methane is very powerful and breaks down quickly, carbon dioxide builds up cumulatively and will continue heating the planet for hundreds to thousands of years.

The problem is that by capturing methane today, we're potentially increasing long-term warming in place of short-term reduction. It’s a good idea to cut methane emissions, but not if it means swapping short-lived greenhouse gases for more permanent ones.