The following chart plots minimum and maximum annual changes in CO2 occurring in May, from 1960 to 2010, measuring minimum and maximum values on a rolling 12-month basis. The color area is the spread between minimum and maximum change. Long plateaus indicate periods in which no new records were being set. Choppy areas indicate shorter time intervals between new maximum or minimum values. The white line is 10-year moving average.
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Here are the top-3 year-over-year CO2 increases which have occurred in May:
1. May, 2003 +2.96 ppm
2. May, 1998 +2.86 ppm
3. May, 2010 +2.76 ppm