When greenhouse gas levels dropped too low in Earth’s distant geologic past, its entire surface became deeply encrusted in ice for millions of years until their levels once again rose sufficiently to melt the ice. Later on, when carbon dioxide levels rose too high in conjunction with the extended volcanic activity that formed the Siberian Traps, the biosphere cooked and the Permian–Triassic extinction event known as the Great Dying occurred. Once the level of CO2 decreased to friendlier levels, life was eventually restored. Next, the extended period of volcanic activity that formed the Deccan Traps released so much carbon dioxide that much of life again was extinguished. Then, once again after much geologic time, balance was finally restored and life resumed.
Today, we see greenhouse gas levels increasing and again temperatures are increasing. However, instead of extreme volcanic activity releasing CO2 over hundreds of thousands and millions of years, the carbon dioxide is being released very suddenly by mankind burning vast amounts of carbon laden fossil fuels.
The wise thing would to have curtailed our consumption of coal, petroleum and natural gas when we realized the problem back in the 80s. Seemingly, however, the taxonomic name ‘Homo sapiens’ (meaning wise man in Latin) should be ‘Homo insapiens’ (unwise man).