World Carbon Levels Caused by Human Activity
Here are some good lecture notes one quantities of carbon in the world.
The accompanying sketch (Figure 11) shows these reservoirs, with amounts given in petagrams of carbon and fluxes in units of petagrams of carbon per year. So, for instance, the atmosphere contains about 740 units of carbon. Terrestrial biology, including all of the plants from phytoplankton to giant sequoia trees and animals from mice to elephants, accounts for about 550 units.
Fossil fuels account for about 5 to 6 units of emission into the atmosphere, and the burning of standing carbon in the form of old growth tropical forests contributes about 1 to 2 units.
Thus, maybe human activities can account for a 30% increase in CO2 over the past 50 years. That would be about a 230 unit increase, and 50*5=250 increase in human production. Of course, it hasn’t beeen 5-6 each year for very long. But it does seem that human activity is responsible for the increased carbon.
John Martin of the Moss Landing Marine Laboratories proclaimed, “Give me a half tanker of iron, and I will give you an ice age.” His proposal was that by fertilizing the Antarctic ocean with iron, the growth in ocean marine plants would sequester large additional amounts of carbon dioxide from the atmosphere and counteract the anthropogenic increases, but numerous environmental concerns have been raised.