On 28 June 1979, at the group of seven summit, the leaders of the world's most powerful countries declared: We need to expand alternative sources of energy, especially those which help to prevent further pollution, particularly increases of carbon dioxide and sulfur oxides the They thus acknowledged the need to halt immediately, at 1979 levels, the concentration of carbon dioxide the atmosphere. In the following five years, they and their developed country partners moved this direction, as their CO2 emissions steadily declined.1 The G7 consensus came at the initiative of America's Democratic President Jimmy Carter, supported by Canada's Joe Clark. This far-reaching consensus was driven part by oil shortages, prices rising to historic highs, and economic growth falling to new lows.Eighteen years later, on 25 July 1997, the US senate passed the ByrdHagel resolution by 95 to 0. It stated that the senate not ratify any treaty signed at by Democratic President Bill Clinton and his vicepresident, Al Gore, if it impose binding limits on the industrialized countries but not on developing countries within the same compliance period and if it would result serious economic harm to the economy of the United States. At the time, the price of oil was close to historic lows and American economic growth was high.This is the range of choice America's international climate change policy under Democratic presidents and their congress. Whether President Barack Obama's policy will be more like Carter's or Clinton's matters much for Canada. In the Conservative party's 2006 platform, Prime Minister Stephen Harper promised to attack climate change in concert with the major industrial nations the He chose climate change as a priority for the G 8 summit Hunts ville, Ontario, June 2010 - the first following the likely death ofthe regime, and the first opportunity for global leaders to replace it with an effective one. In the autumn 2008 election campaign Harper again displayed his internationally oriented cooperative approach, promising to deal with climate change through a cap-and-trade system embracing Canada, the United States, and Mexico, hitherto unconstrained by the regime.As president, Obama will probably say yes to Canada and seek to create an effective climate change regime for North America. For the first time it will bind Canada, the US, and Mexico to control their carbon emissions and do more for the global ecology than they could on their own. Obama is driven by his campaign promise to move aggressively on climate change and to make the NAFTA regime do more for the environment. He has reaffirmed his commitments and appointed many climate-committed architects of the initial NAFTA trade-environment regime as senior members of his team. Obama's choice of a cap-and-trade system as the centrepiece of his climate plan and his impressive popularity Canada will make it easy for Harper to achieve a far-reaching regional deal. This rapid start on an effective regional regime could form the basis of a global beyond Kyoto framework.THE POLICY ISSUESThe coming together of Obama's America and Harper's Canada on climate change matters much for the world. Uncontrolled climate change could jeopardize human life on the planet and there is no time to lose. In developed countries, the clearest effects of climate change are sporadic heat waves, forest fires, hurricanes, and, soon, chronic sea-level rise. For Americans, hurricanes Rita and Katrina were a wakeup call for what could come. For Canadians, melting Arctic ice has less shocking but still significant effects.The key international policy choices to control carbon time to stop deadly climate change are fivefold. First, the new regime have to bind all the major carbon-producing powers of the future. That include, notably, the G8, all the European Union, China, India, Brazil, Mexico, South Africa, and perhaps the rest of the group of 20. …