Today on This Green Earth, Chris Cherniak and guest host Claire Wiley speak with (02:10) Walt Meier, Senior Research Scientist with the National Snow and Ice Data Center who shares the science behind studying Environmental Arctic Change and what the outlook is for Arctic sea ice.Then, (26:18) acclaimed author Ben Rawlence comes on the show to discuss his new book, The Treeline, which takes us along the critical frontier of our warming planet from Norway to Siberia, Alaska to Greenland, to meet the scientists, residents and trees confronting huge geological changes.