If you think of carbon foootprint ZOOKER, then you need to look in to move people over to public transport. Close to 16 million passengers at MAN used private transport to/from the airport according to the CAA 2012 survey. In addition to this you have the MAN workers carbon footprint from their daily private commute.
If we look at only the passenger CO2 emmision from their private transport, we are talking many 10,000s on tonnes CO2 - so let's start calculate. The survey says the average travel group size at MAN is 2.1 passengers, so let us say they come together to the airport. An average car today emits around 200 g CO2 per km. A low estimate of how far the passengers are traveling to get to the airport would be 30 km (based on the same survey), but let's use it for this calculation.
16 million passengers / 2.1 passengers x 30 km x 200 g CO2 per km = 45,714 tonnes CO2
If we so convert this to jetfuel, this equals to 18.1 million litres or if we think of aircraft this equals to filling 56 empty Airbus A380 to the rim with jetfuel (fuel capacity for an Airbus A380 is 323,546 litres).
This is a low estimate since the same survey also say a share are driven to the airport (wave off) and then we are talking double distance. The wave off share is around 8%. Had MAN had the same public transport share as another MAG airport, STN, the CO2 emission from private passenger transport been 57.9% of what it was in 2012. That would have saved a lot of green area around MAN - and the sheep could have continued to eat the grass north of the Ringway Road.