The Theme of 2015 is
"Seven Billion Dreams; One Planet; Consume with Care"
The well-being of humanity, the environment, and the functioning of the economy, ultimately depend upon the responsible management of the planet’s natural resources. Evidence is building that people are consuming far more natural resources than what the planet can sustainably provide.
Many of the Earth’s ecosystems are nearing critical tipping points of depletion or irreversible change, pushed by high population growth and economic development. By 2050, if current consumption and production patterns remain the same and with a rising population expected to reach 9.6 billion, we will need three planets to sustain our ways of living and consumption.
The WED theme this year is therefore "Seven Billion Dreams. One Planet. Consume with Care." Living within planetary boundaries is the most promising strategy for ensuring a healthy future. Human prosperity need not cost the earth. Living sustainably is about doing more and better with less. It is about knowing that rising rates of natural resource use and the environmental impacts that occur are not a necessary by-product of economic growth.
See more at: http://www.unep.org/wed/theme/sustainable-consumpion.asp#sthash.Oao9fTgD.dpuf
World Environment Day official Video :