It's officially called the U.N. Summit on Sustainable Development, but everyone is calling it Rio+20. Twenty years ago, leaders from around the world met in the Brazilian city of Rio de Janeiro for the first Earth Summit. That meeting was fraught but productive, committing the nations of the world to dealing with climate change and other major environmental ills. Since then, though, the environment has mostly worsened, while nations have mostly bickered. International delegates will try again on June 20 to June 22 at the Rio+20 meeting, but expectations are lower, with U.S. President Barack Obama and most other developed world leaders giving the meeting a pass. That's too bad the list of priorities for a planet in peril is a long one. Here are the top 10 issues up for discussion in Rio this month.