This Colorado-built satellite will leave methane polluters nowhere to hide

Carbon dioxide isn't the only climate-warming gas that's reached record levels in the last few years.

Scientists are now racing to explain what's causing methane — CO2's potent sidekick — to build up in the atmosphere at an alarming pace. That's especially concerning because the gas packs a short-term punch, trapping 84 times more heat than carbon dioxide in the first 20 years after its release.

Methane is also a tricky problem due to the variety of natural and human-made sources. The invisible gas seeps out of landfills, wetlands, cow guts and oil and gas operations. That makes it far tougher to pin down than carbon pollution, which can usually be tracked to the nearest smokestack or tailpipe.