BBC: A big spike in atmospheric carbon dioxide levels means the greenhouse gas is about to pass a symbolic threshold.
Twenty-sixteen will very likely mark the first time the concentration of CO2, as measured atop Hawaii's famous Mauna Loa volcano, has been above 400 parts per million for the entire year.
The forecast is from the UK Met Office.
It says carbon dioxide levels have seen a surge in recent months as a result of the El Nio climate phenomenon, which has warmed and dried the tropics....