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CO2 in Atmosphere Reaches Record-Setting 400 PPM
By Tyler Collins

The National Oceanic and Atmospheric Administration (NOAA) reported that on May 9, 2013 the daily mean concentration of carbon dioxide in the atmosphere of Mauna Loa, Hawaii, surpassed 400 parts per million (ppm) for the first time since measurements began in 1958. Mauna Loa is the oldest continuous carbon dioxide (CO2) measurement station in the world and the primary global benchmark site for monitoring this potent heat-trapping gas.

Before the Industrial Revolution in the 19th century, global average CO2 was about 280 ppm. During the last 800,000 years, CO2 fluctuated between about 180 ppm during ice ages and 280 ppm during interglacial warm periods. Today’s rate of increase is more than 100 times faster than the increase that occurred after the last ice age ended.

Climate scientists have been warning that the atmospheric CO2 concentration must be reduced to 350 ppm in order to avoid the disastrous impacts of climate change. However, with the CO2 in the atmosphere climbing so fast, it won’t be long before we surpass 450 ppm. At this level, scientists predict that average global temperatures will have increased by two degrees Celsius and the planet will have reached the “point of no return.”

“Carbon dioxide pumped into the atmosphere by fossil fuel burning and other human activities is the most significant greenhouse gas (GHG) contributing to climate change,” noted the NOAA report.

Once emitted, CO2 added to the atmosphere and oceans remains for thousands of years. Thus, climate changes forced by CO2 depend primarily on cumulative emissions, making it progressively more and more difficult to avoid further substantial climate destabilization.

“There’s no stopping CO2 from reaching 400 ppm,” said Ralph Keeling, professor and geochemist at Scripps Institution of Oceanography. “That’s now a done deal. But what happens from here on still matters… and it’s still under our control. It mainly comes down to how much we continue to rely on fossil fuels for energy.”

Posted: May 21, 2013