CO2 variability (IMAGE) National Institute for Environmental Studies Caption Maps of magnitude of CO2 variability over airports worldwide. Large and red circles indicate large variability. Cities are denoted by nearby airport codes. It was found that the CO2 variability was large over airports where a nearby city has large CO2 emissions. Credit CONTRAIL Team (Photo: Japan Airlines) Usage Restrictions Credit required. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.