Russia has given its final seal of approval to the international Kyoto protocol on climate change. That means the 1997 United Nations agreement aimed at curbing global warning becomes effective worldwide.President Vladimir Putin signed the parliament’s ratification of the pact late last night. The UN accord had already received the backing of 126 countries. It needed Russia’s support to become internationally binding after the world’s largest polluter, the US, pulled out in 2001. To come into force the pact needed to be ratified by countries accounting for at least 55 percent of developed nations’ greenhouse gas emissions. The Kyoto Protocol obliges rich countries to cut overall carbon dioxide emissions by 5.2 percent below 1990 levels in four to eight years time.