"A campaign to plant a billion trees within a year was launched at the United Nations Climate Change Conference in Nairobi, Kenya, today in a bid to encourage all sectors of society, from concerned citizens to philanthropic corporations, to take small but practical steps to combat what is probably the key challenge of the 21st century.

"Action does not need to be confined to the corridors of the negotiation halls," UN Environment Programme (UNEP) Executive Director Achim Steiner said, noting that intergovernmental talks on tackling climate change can often be difficult, protracted and sometimes frustrating, especially for those looking on." More