![Naked Scientists Special Editions show](https://d3dthqtvwic6y7.cloudfront.net/podcast-covers/000/034/511/small/naked-scientists-special-editions.png)
Summary: This week in the Planet Earth Podcast, how hikers and walkers could be unwittingly changing the landscape by spreading alien species; what it's like to work as a marine biologist in the Arctic in temperatures of minus 40C; and exactly how stable is the West Antarctic Ice Sheet?