April set a record you probably didn't hear about. You likely saw news that last month was the warmest April on record, as measured by average global surface temperature and by ocean surface temperature. January-April 2010 also set a new average temperature record for the 4-month period. Records date back to 1880. The Little Ice Age ended in 1850.
The news you didn't hear is that a new April record was set for year-over-year increase in carbon dioxide (CO2). Atmospheric CO2 in April 2009 was 389.46 parts per million (ppm) and was 392.39 ppm in April 2010, for a year-over-year April increase of 2.93 ppm. Data obtained from the Mauna Loa Observatory and is published by NOAA here. The data series begins with March 1958.
Measuring the monthly change in CO2 across a rolling 12-month window is relevant because CO2 experiences seasonal fluctuations. It rises in the (Northern hemisphere) spring and summer and falls during the winter. April 2010 was the 14th highest monthly increase in CO2 in the entire data series. CO2 has almost continuously increased on a year-over-year basis. There have been only eight out of 613 months since March 1959 in which CO2 levels declined. The last monthly decline occurred in September 1974.
The following chart plots minimum and maximum annual changes in CO2 occurring in April, 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 increase. 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.
Click chart to view full-size
Twenty-three of the top-30 monthly CO2 increases (in all months) have occurred in the past 12 years. "Top-30" equates to top-5%. The prior new monthly record was set in March 2009. Monthly annual increase records for June, July, August, September, October, November and December were all set in 1998. Prior to 1998, the other seven monthly records in the top-30 are found only in 1988 and 1973. TheRaven will be monitoring NOAA data to report new monthly records as they occur.
Since the worst global economic crisis in over 75 years didn't put a dent in CO2 growth, TheRaven expects that global economic recovery coupled with relentless population growth will trigger a few new CO2 growth records.