A new study has found that global annual sales of renewable energies such as wind, solar and biofuels could more than quadruple in a decade to nearly $170 billion if oil prices remain high and technology costs fall. Such investments are a necessity if climate catastrophe is to be averted, but in itself is insufficient to solve the problem, as major advances in energy efficiency, population reduction and sustainable consumption are also desperately needed if global ecological sustainability is to be achieved in our lifetimes.