Fifty-five countries have submitted pledges for curbing greenhouse gas emissions to the UN climate convention.Governments were asked to do so before 31 January by the Copenhagen Accord, the document produced at December's U.N climate summit in the Danish capital.The U.N's top climate official, Yvo de Boer, said the pledges would invigorate the U.N process. Submissions have come from major developed and developing countries and collectively account for about three-quarters of the world's emissions from energy use.The 55 countries sending in pledges include E.U member states, U.S and Japan as well as the four Basic bloc countries (Brazil, China, India and South Africa) that were the principal architects of the Copenhagen Accord.