Aviation, melting sea-ice and polar bears.

On 11 May 2019, the Mauna Loa, Hawaii, Earth System Research Laboratory reported the highest CO concentration in human meteorological history. Continuing CO rise will devastate ecosystems, and ice dependent species like polar bears ultimately will disappear. Commercial aviation is presently a relatively small CO contributor, but this CO intensive mode of transportation is projected to increase greatly. Scientists and conservationists are often among the most frequent of flyers, despite their recognition that emissions must be reduced. Here we illustrate the carbon footprint of air travel in terms of its impact on the sea ice habitat necessary for polar bear persistence, and suggest our colleagues reduce their air travel where-ever possible. Each metric ton of CO emitted melts ~3 m of arctic summer sea ice, and current air travel melts over 5000 m each year. Each scientist making the short flight from Copenhagen to Oslo to join an IUCN polar bear meeting will melt ~1 m of Arctic summer sea-ice. Annually hundreds of scientists and conservationists make frequent flights of much greater distances for AMAP, CAFF, IUCN, and other conservation related meetings. Much of this travel could be avoided with better planning and employing internet linkages for remote participation. When air travel, such as for necessary fieldwork, cannot be easily substituted by Web linkage, we all should search for routes and carriers allowing the lowest CO emissions. We encourage all of our colleagues to join 'No Fly Climate Sci' to show their commitment to CO reduction and learn more about doing so. As scientists, if we are serious about preserving polar bears and their Arctic sea ice habitat, we need to walk the talk and show an example for the rest of society by significantly reducing our air travel.