The Kyoto protocol meant to rein in global warming enters force this Wednesday, at last. Agreed by governments at a 1997 U.N. conference in Japan, the ratification by Russia last autumn finally gave it the ballast it required.Kyoto now has the backing of 141 nations — thirty of them considered ‘industrialised’ — representing more than 61% of emissions of gases which trap heat inside the atmosphere. The pact aims to reduce the amount of greenhouse gases developed countries produce, by 5.2 percent of 1990 levels during the five-year period 2008-2012. The legally binding goals mainly concern power plants, factories and cars. Yet some backers are also slackers: Spain, Portugal and Ireland are way above their targets; Britain has lowered the bar for its industries; Italy is upset about costs. The main gases are carbon dioxide, mostly caused by burning fossil fuels, methane from farming and rubbish dumps, nitrous oxide from fertilizer use, and hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride from various industrial applications. Companies must meet targets to cut these, or, in a traded market, buy allowances to emit. The United States, the world’s biggest polluter, is not on board, saying Kyoto is too expensive and wrongly leaves out developing nations. China and India are not in. Australia is not either. The European Commission has poured cold water on the EU’s determination to keep Kyoto going post-2012 in the face of reluctance elsewhere in the world. The UN says this is only the first step in a long, hard struggle with climate change. Some experts say that limiting the planet’s heat increase in fifty years to two degrees will require CO2 emissions to be cut in half.