Spring has Sprung
By Alison Hawkes
Ahh spring. Just three more days and it’s officially started. We know to expect the usual delights: warmer weather, rain, and with that a giant bloom of flowers, leaves, and fresh growth.
So giant, in fact, that all that photosynthesis will draw down atmospheric CO2 levels by several ppms. Check it out. This graph provided by the Mauna Loa research station in Hawaii shows the continuous climb in CO2 levels. The red line shows monthly mean values measured from the top of the volcano. The oscillations demonstrate the drop during the â€œspring is sprungâ€ season and the peaks during the fall die off, which releases a boatload of CO2.
The black curve represents the same data, corrected for the seasonal vegetative cycle, and shows the relatively steady upward curve that has us worried. This graph shows the same idea, but over a 1960-2010 time period.
One thing not so clear in these graphs is the trend towards an earlier drawdown in CO2 by several days. CO2 Science provides a good summary of the literature on this phenomenon. Is it warmer weather causing plants to bloom earlier? Or higher levels of CO2 that cause plants to grow bigger and faster?