(a) The United Nations Convention on Climate Change ratified by more than 50 countries became effective on 21st March, 1994. The United Nations Framework Convention on Climate Change (UNFCCC) is an international environment treaty adopted on 9th May, 1992 and opened for signature at Earth Summit in Rio de Janeiro from 3rd to14th June, 1992. It entered into force on 21st March 1994 after a sufficient number of countries had ratified it.