Human energy use has led to an increase in the production of greenhouse gases.
Humans produce greenhouse gases faster than they can be taken up by carbon users, such as plants.
This increase in greenhouse gases has led to a continued, irreversible rise in planetary temperature.
Source: Boundless. “Environmental Problems Associated with Fossil Fuel Use.” Boundless Chemistry. Boundless, 13 Nov. 2014. Retrieved 29 Nov. 2014 from https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/thermochemistry-6/energy-use-and-the-environment-62/environmental-problems-associated-with-fossil-fuel-use-291-1025/