Paul P.S. Teng*

TWENTY YEARS after the first Earth Summit in 1992, preparations are under way to convene the third such meeting in the same city where it all began, Rio de Janeiro. Most of the worlds heads of state and government are expected to attend the high-powered conference on 20-22 June, which follows the second summit 10 years ago in Johannesburg. Rio+20 will focus on promoting a global "green economy" through the creation of an "Institutiona