World-wide battle deaths per 100,000 people from 1940s to 2000s.

Timeline from 400BC to 2000AD showing the number of deaths from all recorded international wars, colonial wars, and civil wars.

World map showing armed conflicts in different regions from 2008 to 2009.

RIO DE JANEIRO (AP) – The earth's environmental systems "are being pushed towards their biophysical limits," beyond which loom sudden, irreversible and potentially catastrophic changes, the United Nations Environment Program warned Wednesday.

Jonathan Watts

Money will be invested in building transport systems that will reduce greenhouse gas emissions

Fiona Harvey and Damian Carrington

Ministers attending clean energy summit in London to be gravely warned about continuing global addiction to fossil fuels

Deborah Zabarenko and Nina Chestney

(Reuters) - Representatives from around the world gather in Rio in June to try to hammer out goals for sustainable development at a U.N.

Some 32 social scientists and researchers from around the world, including a Senior Sustainability Scholar at Arizona State University, have concluded that fundamental reforms of global environmental governance are needed to avoid dangerous changes in the Earth system.

Alex Duval Smith

On another beach in a different world, Chinasa Paul would be sipping a soft drink bought by his parents. But if the 15-year-old eats today in Lagos, it will be thanks to tips he receives for lugging crates of drinks up and down Kuramo Beach.

Bill Scanlon

Providing clean, renewable energy to the 1.4 billion people who are living without electricity is the No. 1 priority of the United Nations, the secretary general of the U.N. said during a visit Aug. 24 to the U.S. Department of Energy's National Renewable Energy Laboratory.