Global carbon dioxide emissions remained flat for a third year in a row, yet far more powerful greenhouse gases keep creeping up , according to the annual report from the European Union and the Netherlands Environmental Assessment Agency.

The U.S., Russia, China and Japan decreased their CO2 output from 2015 to 2016, while the EU stayed flat and Indias emissions continued to increase. But emissions of methane and nitrous oxide have been increasing.

Methane molecules trap roughly 30 times more heat than carbon dioxide over a century, and the gas comes from agriculture, coal and gas production, and landfills. Nitrous oxide, known as laughing gas, trap about 300 times more heat than carbon dioxide; its emitted by soil fertilizers and chemical production.

Agricultural statistics are not updated as frequently as energy and industry-related numbers, so the report did not include complete data for those gases. But a preliminary assessment showed an upward trend in the U.S., China, Japan, India, Germany, the United Kingdom, France, Poland, Italy and Spain.

Nitrous oxide emissions could get much worse as a result of global warming. Arctic permafrost contains roughly 67 billion tons of the gas, and, as that ice layer thaws, up to one-fourth of the region could become a net emitter, according to a study published in July.