The Bonnaroo Festival is releasing what is essentially a best of album, with a list of top alternative acts recorded live at the festival. There’s Wilco, Pearl Jam, Death Cab for Cutie, The Decemberists and a good few more. But the aim isn’t to make money or even promote the festival, oh no. The aim is to spread awareness of a forthcoming piece of climate change legislation going through the US Senate, and to mobilise music fans to write to Obama or Senators to voice your support for action on climate change and get the bill to pass. Just like they did with national healthcare. Ahem.