"ROME (Thomson Reuters Foundation) - Human activity has pushed the planet across four of nine environmental boundaries, sending the world towards a "danger zone", according to a study published on Thursday in the journal Science.

Climate change, biodiversity loss, changes in land use, and altered biogeochemical cycles due in part to fertilizer use have fundamentally changed how the planet functions, the study said.

These changes destabilize complex interactions between people, oceans, land and the atmosphere, said the paper "Planetary Boundaries: Guiding human development on a changing planet" by 18 leading international researchers."

Chris Arsenault reports for Thomson Reuters Foundation January 15, 2015. [2]