Saturday, October 7, 2017
Without the presence of carbon dioxide, methane, water vapor, ozone and other gases in the atmosphere, our planet would be perpetually and completely frozen over. The greenhouse effect sustains life. Indeed, in Earth's early geologic past when the sun's output was much fainter, temperatures were much higher due to much higher levels of methane. Nowadays, the sun is much brighter while greenhouse gases are fortunately much lower. Unfortunately however, mankind is disrupting this balance by artificially unsequestering large amounts of carbon. This is causing temperatures to rise and to release ever increasing amounts of methane via melting permafrost and methane hydrate degasification. The ocean's ability to absorb excess carbon dioxide is decreasing and ocean acidification is increasing. The greenhouse effect, instead of being a giver of life, will increasingly become a taker.
After the Earth first formed, the temperatures were higher than they are now. Anaerobic life evolved and flourished in conditions with high methane and CO2 levels for hundreds of millions of years.. Then Cyanobacteria came into being and consumed the CO2 while releasing oxygen, creating a great dying off of the anaerobics. The CO2 levels got so low that the Earth became what scientists call Snowball Earth. Eventually, however, the CO2 and oxygen levels balanced out and new life forms evolved and flourished in the pre-Cambrian Period. After this, the only times that great extinctions occurred were when CO2 levels soared.