Green light: Undercover activist, coral at risk and giant pandas return to UK

Activism • Calls for inquiry into conduct of undercover police officer Mark Kennedy • Spying: green undercover operatives' tales revealed • Emily Apple: I can't forgive Mark Kennedy's betrayal • Mark Kennedy knew of second undercover eco-activist Environment news • US commission on BP oil spill demands tougher safety regulations • Conservationists unveil plans to save coral from extinction • Opposition mounts against Lincolnshire 'mega-dairy' • Electric cars win top awards at Detroit motor show Comment • Julie Hill: Time to get a grip on our material world • Damian Carrington: Violent rhetoric infects many US debates, including climate change • Felicity Carus: Dirty Business film debunks 'clean coal' myth • Ben Caldecott: What exactly are green bonds? Multimedia • In pictures: The world's most important corals in need of conservation • The week in wildlife • Share your photos of frost Green living • Al Gore, Gary Neville or Cheryl Cole: who would you trust on climate change? • Which is the bigger eco-villain: plastic or paper? • Hugh's fish fight takes Tesco to task • Ada Zanditon's innovation: sustainable biomimicry clothes • How to make cycling more fun: turn your bike into a horse (and other ideas) Best of the web • SolveClimate: Military v climate spending: How China outguns the US on clean energy • Earth Island Journal: Mongolia's wilderness threatened by mining boom • BusinessGreen: Supermarkets accused of 'misleading' fish labelling For more of the best environment comment and news from around the web, visit the Guardian Environment Network . ...And finally • Pass notes No 2,908: the giant panda How a new round of 'panda diplomacy' will see Edinburgh zoo welcome two new pandas from China