NORMAN — There are three facts everyone should know about carbon dioxide:
1. CO2 is a greenhouse gas. This is physics and not subject to debate. The CO2 molecule re-emits heat in Earth’s atmosphere. This is good, because Earth’s average temperature would be unbearably cold without it. Like many good things, however, too much is bad.
2. Levels of CO2 in the atmosphere have increased by 40 percent over pre-industrial values. We know this by directly measuring it since 1958 and from measuring CO2 in ice cores that date from more than 600,000 years ago.
3. Most of the increase is anthropogenic, or caused by man. We know this because we can measure the isotopic value of CO2 in the atmosphere, which precisely fingerprints it as derived from fossil fuels, and we can detect the corresponding (slight) reduction in O2 that accompanies any combustion.
Earth’s geological record archives many past examples of CO2-forced climate change, including ones with much higher values of atmospheric CO2. Humans, however, have never experienced these “alternative Earths.”
The fastest such change occurred 56 million years ago, but the rate of carbon emissions (<2 petagrams of carbon/yr.) was much slower than our current rate (about 10 petagrams of carbon/yr.), and even this change led to numerous extinctions. Earth’s atmosphere recovered but required thousands of years to “scrub” the excess CO2 to pre-perturbation values.
Current CO2 increases are happening at a geologically unprecedented rate because we are combusting carbon sequestered over millions of years and releasing that carbon geologically instantaneously. That is, we are short-circuiting the carbon cycle.
We find this message uncomfortable because the world economy runs on carbon. The argument goes that to change would spell economic ruin. Or would it?
In Abu Dhabi this January, the International Renewable Energy Agency (IRENA) reported that renewables are increasingly competitive with fossils fuels.