The industrial activities of mankind continue to emit billions of tons of carbon dioxide, a greenhouse gas, into an incredibly thin atmosphere in increasing amounts year after year. This gas can remain in that atmosphere for more than a hundred years with each year building on top of the hundred previous. Meanwhile, deforestation activities continue to remove a natural mechanism for removing that gas from the atmosphere, a natural sink.
Natural sinks for carbon dioxide work to balance the emissions through absorption into the world’s oceans and increased vegetation growth. However, these mechanisms cannot keep pace, and the atmospheric concentration of carbon dioxide continues to steadily rise. These mechanisms also have their limits, and should oceans and forests stop absorbing carbon dioxide, the atmospheric concentration will skyrocket as these environments turn into a source for CO2 rather than a sink for it.
As the concentration of greenhouse gases in the atmosphere rises, more heat is trapped near the Earth’s surface, resulting in rising global temperatures. As these temperatures rise, they feed into many natural positive feedback mechanisms. As ice melts, it releases trapped greenhouses gases into the atmosphere and leaves behind much darker ocean water and land masses which absorb more heat than the light-surfaced ice. Also, warmer air can hold more water vapor, a much stronger greenhouse gas than CO2. These positive feedback mechanisms work in unison with rising CO2 levels to push temperatures higher.
These higher temperatures cannot be accounted for by natural climate forcing mechanisms that have historically driven climate change. Temperatures are rising too fast to be a result of variations in the Earth’s orbit around the Sun or shifts of continental tectonic plates which influence climate over thousands of years. Short term influences such as volcanic and solar activity and ocean and wind patterns have not seen variations that correspond with rising temperatures, and no climate changing comets or asteroids have impacted the planet over the industrial period. All of which leads back to mankind.