The best news about climate change that we've heard lately is that for three years in a row, the world's energy-related emissions of carbon dioxide, the most important greenhouse gas, have been flat. The gas has continued to accumulate in the atmosphere, but emissions haven't gone up, even as economies have ­continued to grow.

But now we learn that there's a major dose of bad news: What's true for carbon dioxide is not at all true for methane, the second most important greenhouse gas. Atmospheric concentrations of this gas — which causes a much sharper short-term warming, but whose effects fade far more quickly than carbon dioxide — are spiking, a team of scientists reported Sunday in the journal Environmental Research Letters.

Methane concentrations in the atmosphere, they report, were rising only about 0.5 parts per billion per year in the early 2000s. But in the past two years, they've spiked by 12.5 parts per billion in 2014 and 9.9 parts per billion in 2015. With carbon dioxide rising more slowly, that means that a higher fraction of the global warming that we see will be the result of methane, at least in the next decade or so.

The paper was written by a team of researchers with the Global Carbon Project, which tracks the flows of this element across the planet and publishes a global methane budget every two years.

"Looking at the scenarios for future emissions, methane is starting to approach the most greenhouse gas-intensive scenarios," said Rob Jackson, a Stanford earth scientist who co-wrote the study. "That's bad news. We're going in the wrong direction."

Methane reaches the atmosphere from a complex collection of human and natural sources. It is the main component of natural gas, and so can leak from drilling operations. But it also emerges from many biological processes, including the flooding of rice paddies and "enteric fermentation" in the stomachs of ruminant ­animals like cattle.

Jackson said some of the rise is "almost certainly" coming from livestock and specifically cattle, and also pointed to rice paddies, landfills and the management of manure in agriculture.

The research thus singles out an often ignored but still major contributor to global ­climate change: the agricultural sector.

Washington post