While they only represent a relatively small fraction of total emissions now, greenhouse gasses from air travel are growing rapidly. That said, one largely unanticipated check against their long-term rise may exist, if the potential sea rise effects of the disintegration of the Greenland or West Antarctic ice sheets become manifest.
This clever Google Maps mashup will show you what I mean:
- Vancouver International Airport
- Logan Airport, Boston
- Newark, New Jersey
- La Guardia, New York
- John F. Kennedy, New York
- Hong Kong International Airport
- Changi Aiport, Singapore
- Sydney International Airport
- Amsterdam Airport (no surprise)
- Dubai International Airport
- San Francisco International Airport
- Etc, etc
Adding 7m to global sea levels (consistent with the melting of all of Greenland, all of West Antarctica, or half of each) would definitely drown a lot of runways. The Tokyo and London airports seem likely to be high and dry, though the cities themselves would be far from it.