Excess carbon in the atmosphere increases the temperature of the earth by absorbing infrared and near infrared light. (ref: http://www.ideaconnection.com/solutions/7510-Excess-Carbon-Dioxide-in-Atmosphere.html)
Carbon dioxide is a greenhouse gas.
Greenhouse effect refers to circumstances where the short wavelengths of visible light from the sun pass through a transparent medium and are absorbed, but the longer wavelengths of the infrared re-radiation from the heated objects are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and a higher resultant temperature. Besides the heating of an automobile by sunlight through the windshield and the namesake example of heating the greenhouse by sunlight passing through sealed, transparent windows, the greenhouse effect has been widely used to describe the trapping of excess heat by the rising concentration of carbon dioxide in the atmosphere.
The increasing amount of carbon dioxide in the atmosphere is increasing the temperature of the earth by absorbing infrared and near infrared light.
How do plants help remove excess carbon? Photosynthesis
Plants use the energy from the sun to remove carbon dioxide from the atmosphere and use it to make carbohydrates (sugars).
Plants take up CO2 (carbon dioxide) from the atmosphere and uses it for the metabolic production of sugars. Carbon dioxide is fixed or incorporated into specific organic molecules by the Calvin Cycle which is the second stage of photosynthesis.