Tuesday, July 22, 2014

CO2 Has Maxed Out For 2014

A milestone passed in May - we reached the maximum level of CO2 for the year and it is now declining, which it will do for the rest of the year. In fact, it was the highest level measured for anytime in the last 800,000 years. The CO2 level increases during the winter when plants are dormant and that increase continues through the spring as plants become more active. The level will typically reach its maximum sometime around May then start declining as plants reach full vigor. The level will begin to rise again in the fall as the plants start to become dormant. This seasonal fluctuation is due mainly to land plants and is larger in the Northern Hemisphere than in the Southern. Measurements taken on Antarctica exhibit only a small seasonal fluctuation. The measurements are so precise that it has been possible to show spring is coming earlier every year. This is the plot of measurements for the last two years, ending on July 19, 2014:
Source: SIO Keeling Curve

Last year (2013) the maximum monthly average came in just below 400 ppm and the highest weekly average was just a little over that level. That landmark level will be reached earlier every year from now on and April 2014 was the first year where the measurements exceeded 400 ppm for the entire month. With May and June added to the list, we now have three of those months. This year, the highest monthly average was better than 402 ppm and the highest weekly average was about 402.4 ppm. That was the highest level in the last 800,000 years and approximately 43.6% higher than pre-industrial levels of 280 ppm. This also continues a long-term trend where the level has increased by about 2 ppm per year.

Source: SIO Keeling Curve

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