Assertion: carbon's level | /r/CapableOf | drop by 6 or 7 ppm
Facets:
value: from may
type: TEMPORAL
Source sentences:
text: As seen in the graph to the right, there is an annual fluctuation — the level drops by about 6 or 7 ppm (about 50 Gt) from May to September during the Northern Hemisphere's growing season, and then goes up by about 8 or 9 ppm.