1. Talk about a case where paleo-climate research could have some big policy implications. washingtonpost.com/climate-enviro…
2. It sounds like scientists just doing what scientists do -- drilling into Greenland ice, withdrawing samples of ancient air from ancient ice...typical.
3. But this ancient air (about 270 years old) turns out not to contain much methane from fossil sources -- the very oldest methane, from deep in the Earth.
4. Scientists can determine this because that old methane won't contain the carbon 14 isotope in it any more -- it will have decayed.
5. 1750 is before fossil fuels. Before industrialization. The implication -- the Earth's geological processes weren't putting much methane into the air back then. And it's not even three centuries ago -- that shouldn't have changed much.
6. Today, though, scientists generally assume very large emissions of old, fossil methane from natural geologic process like mud volcanoes, underwater seeps, etc -- something like 45 million tons. earth-syst-sci-data.net/8/697/2016/ess…
7. If that assumption is wrong, then there could be a big gap in the global methane budget. And it would have to be filled by fossil fuels -- since after all, they, too, produce emissions of very old methane.
8. Ergo the very big conclusion -- we could be underestimating fossil fuel related methane leaks and other emissions by 25 to 40 percent! Study here nature.com/articles/s4158…
9. Now remember, atmospheric methane is going up fast. But methane is peculiar -- it causes a lot of warming but really only acts over about a decade. After that, it's gone (though it leaves carbon dioxide behind). 
10. So cutting down on methane emissions immediately would put the brakes on a lot of warming.
11. If it is correct, then, the new research means that finding and fixing fossil gas leaks would have a really big climate payoff, even bigger than we thought.
12. Those are some potent conclusions to draw based on ancient air bubbles. But, that's what the new study suggests. Our coverage here washingtonpost.com/climate-enviro… /end
