Arctic monitoring stations show carbon dioxide levels are now above 400 parts per million. Carbon dioxide is the chief climate-change gas and stays in the atmosphere for 100 years. Before the Industrial Age, carbon dioxide levels were 275 ppm.
The world's air has reached what scientists call a troubling new milestone for carbon dioxide, the main global warming pollutant.
Money will be invested in building transport systems that will reduce greenhouse gas emissions
The world's biggest development banks have made a fundamental investment shift from roads to public transport, under a $175bn (£111bn) initiative to promote buses, trains and cycle lanes that was unveiled on Wednesday at the Rio+20 Earth summit.