Mauna Loa is a mountain in Hawaii and sounds like a nice place to live and work.  It is the location of an observatory where the US Government Agency NOAA (National Oceanic & Atmospheric Administration) measures the amount of carbon dioxide in the atmosphere on a regular basis. 

Thanks to the resources of the US Government this data is published and updated monthly on an easy to access website:  http://www.esrl.noaa.gov/gmd/ccgg/trends/ from which the graph below is taken.

The data tells a story about the annual increase in the amount of atmospheric carbon dioxide.  Every winter, while much vegetation in the northern hemisphere lies dormant, the amount of carbon dioxide in the atmosphere increases.  In summer rapid plant growth pulls carbon dioxide out of the atmosphere through photosynthesis, an annual cycle that shows up clearly in the Mauna Loa graph. 

But every year the peak amount of carbon dioxide in the atmosphere is higher than the year before.  It is now well over 390 parts per million (ppm) and increasing at about 2 ppm per annum.  This is our contribution, from the burning of fossil fuels such as oil, coal and gas.  

The peak figure may well exceed 400ppm in 2014 and, if not then, it certainly will in 2015. This figure has symbolic importance but perhaps more important is the figure of 450ppm, above which level it is estimated that global warming will exceed two degrees Celsius.  At the current rate of increase, this will take place in about 2025, many years earlier than previously thought, with potential consequences we are only beginning to understand.

By Adrian Shaw