Some analysis suggests that emissions and contrails from planes, can have positive and negative impact on global warming (e.g. reflecting sun or acting as greenhouse) depending on time of day, altitude, cloud and atmospheric conditions, time/season of year, geodesic location.

Update 10/02/09: Thank you very much for your participation in the Mozilla Labs Weave Web UI Design Challenge. The Weave team will go through the submissions in the coming days, evaluate, and discuss. Mozilla should finish this process by the end of next week, after which they will provide...