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A recent study has calculated the amount of atmospheric CO2 that has been captured by a new green belt in Leipzig, Germany. The footprint ranges from 29 to 218 tonnes of CO2 sequestered per hectare depending on the level of mortality among the trees and their rate of growth. If the area was given over to lawn without trees it would be a source of increased atmospheric CO2. The city would need an area of green belt about 33 times its size to mitigate all its emissions.