Since about 1750, human activity has increased the concentration of carbon dioxide and other greenhouse gases. Measured atmospheric concentrations of carbon dioxide are currently 100 ppm higher than pre-industrial levels. Which of these is NOT a human impact on the carbon cycle?
Responses
A Volcanoes have released significant carbon emissions with eruptions.Volcanoes have released significant carbon emissions with eruptions.
B Burning fossil fuels transfers carbon from the geosphere into the atmosphere.Burning fossil fuels transfers carbon from the geosphere into the atmosphere.
C Increased CO2 emissions from fossil fuel usage has increased ocean CO2 levels and led to ocean acidification.Increased CO 2 emissions from fossil fuel usage has increased ocean CO 2 levels and led to ocean acidification.
D Deforestation and land use changes have increased atmospheric CO2 by decreasing carbon stored in and used by plants in the process of photosynthesis.Deforestation and land use changes have increased atmospheric CO 2 by decreasing carbon stored in and used by plants in the process of photosynthesis.