Scientists have obtained baseline numbers by analyzing air bubbles trapped in ice core drillings fron the Greenland icecap, and Antarctica, showing constant values at about 280 ppm for the 800 years prior to the early 1800's.
(air bubbles; trapped; in ice core drillings; T:fron the Greenland icecap, and Antarctica) (the Greenland icecap, and Antarctica; showing prior; L:at about 280 ppm for the 800 years) (Scientists; have obtained; baseline numbers; by analyzing air bubbles) Context(Scientists have obtained,List([0, 24))):(Scientists; have obtained baseline numbers by analyzing; air bubbles trapped in ice core drillings fron the Greenland icecap, and Antarctica)
Scientists have obtained,List([0, 24))
air bubbles the Greenland icecap, and Antarctica Scientists Scientists
trapped showing prior have obtained have obtained baseline numbers by analyzing
in ice core drillings T:fron the Greenland icecap, and Antarctica
L:at about 280 ppm for the 800 years
baseline numbers by analyzing air bubbles
air bubbles trapped in ice core drillings fron the Greenland icecap, and Antarctica