Enjoy, Explore, and Protect the Planet Sierra Club Allegheny Group, Pennsylvania Chapter

Climate Change

A Milestone We Did Not Want – CO2 Concentration Exceeded 400 ppm

The remote mountaintop Mauna Loa Observatory (MLO) in Hawaii is an ideal location for monitoring the amount of CO2 in the atmosphere. For 24 hours on May 9 the CO2 concentration in the atmosphere atop exceeded 400 parts per million, or 0.04 pct. That is the highest CO2 level for more than two million years, it is the highest concentration in human history, and is a historically rapid increase of about 120 ppm since before the industrial revolution began in 1750. Passing 400 ppm is also an indication that the current efforts to curb CO2 emissions are inadequate, and we are on course for dramatic changes in the Earth’s climate.

The following is from a 8 March 2013 article in the Guardian.

Carbon dioxide levels fluctuate seasonally, with the highest levels usually observed in April. Last year (2012) the highest level at Mauna Loa was measured at 396.18ppm.

What is disturbing scientists is the the acceleration of CO2 concentrations in the atmosphere, which are occurring in spite of attempts by governments to restrain fossil fuel emissions.

According to the observatory, the average annual rate of increase for the past 10 years has been 2.07ppm – more than double the increase in the 1960s. The average increase in CO2 levels between 1959 to the present was 1.49ppm per year.

The Mauna Loa measurements coincide with a new peer-reviewed study of the pledges made by countries to reduce CO2 emissions. The Dutch government’s scientific advisers show that rich countries will have to reduce enissions by 50% percent below 1990 levels by 2020 if there is to be even a medium chance of limiting warming to 2C, thus preventing some of climate change’s worst impacts.

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