This cartoon by Adams from The Daily Telegraph portrays U.S. President Barack Obama as Wile E. Coyote, a character from Chuck Jones's famous Warner Brothers animation series. The cartoons mostly involve Coyote chasing the Road Runner, a fast-running bird. If a chase sequence happens upon a cliff, the Road Runner is not affected by gravity, whereas the Coyote will realize his error eventually and fall to the ground below (see video here).
The cliff in Adams cartoon is the fiscal cliff, the metaphor used to describe the negative economic effects that could result from tax increases, spending cuts, and a corresponding reduction in the US budget deficit beginning in 2013 if existing laws remain unchanged. Obama has been trying hard to get Congress to agree a deal to avoid the fiscal cliff, but it looks increasingly likely that no agreement will be reached before tomorrow's deadline (hence the 2012-2013 reference). In the meantime, Obama remains suspended in thin air, attempting to defy the laws of gravity (aka economic reality).
For more fiscal cliff cartoons, see The Cagle Post.