Why does carbon dioxide get so much attention?

Answer 1

Examinations of Antarctic ice cores reveals atmospheric concentrations of CO2 have varied from 250 ppm to 290 ppm over the past eight hundred thousand (800,000) years. The natural rate of change was typically about 5 ppm per thousand years, between these two extremes.

Beginning in the year 1700, atmospheric CO2 concentrations rose rapidly from 280 ppm to 290 ppm. This was some ten times faster than at any time in the previous 800,000 years, though still not any real cause for alarm. At that rate it would have taken centuries more to pass 350 ppm, which many scientists consider a possible maximum sustainable level.

From 1900 to 1950 CO2 levels rose another 10 ppm, to 300. Now instead of ten times faster than any natural rate of change, CO2 was climbing 40 times its natural fluctuation rate. From 1950 to 1960 it rose 15 ppm, climbing at 133 times the natural rate. Between 1970 and 1975 it rose from 325 to 330 ppm, accelerating to 200 times the natural rate of fluctuation. We passed 350 ppm in 1988, and we are now close to 400 ppm. Before 2050 we will pass 500 ppm.

The concern is that earth's natural carbon sinks cannot cope with this rapid change, and that the increase will drive up the temperature. Earth's permafrost also contains billions of tons of CO2 and methane (CH4). Methane is about 25 times as potent a greenhouse gas as CO2 is. As the permafrost melts, the release of this gas is expected to create a feedback loop further accelerating earth's warming.

The consequences of global warming are only barely being realized now, with slightly increased storm energy and slightly greater incidence of coastal flooding. As sea levels gradually rise from melting glacial water, these effects are expected to become more pronounced. There is enough ice in Greenland to raise ocean levels close to 20 feet.