The director of campaigns at the Howard League, Andrew Neilson, said a move away from a mandatory target system for police was likely to be the main reason for the third successive fall.

BBC: Child arrests continue to fall, says Howard League

While the U.S. delegation says it doesn't want to be an obstacle to a new agreement, Washington remains opposed to steps many other countries support, such as mandatory emissions cuts by rich nations and a target for limiting the rise in global temperatures.

NPR: Climate Experts Mull Payment to Stop Deforestation