U.N. climate talks starting in Mexico this month will seek a complex set of interlocking deals to slow global warming but will fall well short of a new treaty, the U.N.’s climate chief said on Wednesday.

Christiana Figueres said that governments had lowered their sights for the November 29-December 10 talks in Cancun, Mexico, after the Copenhagen summit in December 2009 failed to reach a sweeping new U.N. pact to slow climate change.

Even so, almost 200 nations faced a balancing act in Cancun, where governments were aiming for a less ambitious but still complex package deal.