Is it true that humans make only a tiny contribution to the Earth’s carbon cycle each year? Yes. Does this mean that humans aren’t causing global warming? No. Science journalist Graham Wayne explains:
Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years (Tripati 2009). (A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years).
In other words, unlike with the natural carbon cycle, humans add carbon to the atmosphere, but don’t sufficiently offset their carbon footprint with things like, say, planting large tracts of additional forests. The result: a small but steady accumulation of carbon in the atmosphere because of human activity. Nature tends to recycle its carbon, generally maintaining a homeostatic balance, while humans don’t. The slow effect over time is global warming.
For more on this issue, see the below link.
How do human CO2 emissions compare to natural CO2 emissions?www.skepticalscience.com
The CO2 that nature emits (from the ocean and vegetation) is balanced by natural absorptions (again by the ocean and vegetation). Therefore human emissions upset the natural…