As Global CO2 Levels Increase, So Does CO2 Exchange in Northern Hemisphere

   Every year across the northern hemisphere of the globe, the seasonal cycle of the earth causes the planet to breathe. CO2 is released in the winter and absorbed in the spring as new plant growth uses the atmospheric CO2 for photosynthesis. A new study lead by Heather Graven at the Scripps Institution of Oceanography UC San Diego suggests that this breathing pattern is becoming significantly more dramatic.

   Many are aware that the amount of CO2 in the atmosphere is steadily increasing every year. Graven’s findings show that the amount of CO2 being absorbed during the summer months and released during winter months has increased throughout the northern hemisphere as well.

   The team collected data from two ground sites: One in Mauna Loa, Hawaii and the other in Barrow, Alaska. Data was also collected from aircraft observations conducted during from NOAA’s Carbon Cycle Group Aircraft Program and HIAPER Pole-to-Pole observations from 2009 to 2011. The team then compared these data to CO2 levels observed in 1958 to 1961 at the same ground sites, as well as aircraft observations collected during an international scientific study known as the International Geophysical Year.  

   Their results were somewhat shocking, with an increase of 32 to 59% seasonal CO2 exchange when the data from 1958 to 1961 were compared to data from 2009 to 2011.  Identifying the specific cause has proven to be difficult. The team compared several complex simulations that use historical data to account for various ecosystem processes, but did not find any clear trend. It is clear however that this increase will not slow down in future years. Furthermore, it is a definitive indicator of large-scale, widespread ecological change that has occurred over the past 50 years, especially throughout boreal forests. Graven’s team calls this a “major shift in the global carbon cycle”, and suggest that this may cause people to “under-predict future changes.” It is very possible that in the next fifty years, the earth's respiration patterns will increase at an even faster rate. The study was published in the journal Science on August 30^th and can be found online.

Source:

Graven, H. D., R. F. Keeling, and S. C. Piper. "Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960." Science Magazine. N.p., 08 Aug. 2013. Web. 15 Sept. 2013. http://www.sciencemag.org/content/341/6150/1085.short