Climate change has been described as diabolical policy problem ... harder than any other issue of high importance that has come before our polity in living memory. (1) To deal with it effectively involves many different policy areas. These include not only the obvious ones like energy, but also others such as macroeconomic and fiscal policy, food security, health, water, trade, biodiversity, and even immigration. The financial implications of climate change--impacts, adaptation, and mitigation--are huge and growing. There is a need for massive deployment of technology, a sector notoriously difficult to regulate. Climate change also involves time frames unknown in public policy. There is currently no overall governance arrangement to integrate all these dimensions. The Bonn-based UN Framework Convention on Climate Change (UNFCCC) secretariat, with its mandate defined by the existing convention and the Kyoto Protocol, can easily be seen as too narrow in scope and expertise, and too small to cope with the scale and complexity of this global challenge. It is often pointed out that the international institutional framework is sectorally based, whereas climate change is inherently a cross-sectoral issue. Another weakness is that the Annex I/non-Annex I distinction on which the convention, the protocol, and, to a large extent, the negotiations under the Bali Road Map are based has outlived its usefulness. The Bali Road Map negotiations have softened this distinction a little by referring to developed and developing countries, but even this cannot adequately reflect the range of responsibilities and capabilities among countries. By 2050, the horizon we need to work toward if the world is to come to grips with global warming forty-two years after the start of the Kyoto Protocol's first commitment period, the evolution of the world's major economies will have rendered these dualities irrelevant. There is also much concern about the lack of effectiveness and efficiency of some of the existing institutions, as can be seen by the criticism directed at the Global Environment Facility (GEF) by developing countries, and by concerns about aspects of the Clean Development Mechanism, which had been voiced in the negotiations. If new institutions were to be formed, therefore, they almost certainly would not replicate the current arrangements. Indeed, the same could be said of sustainable development in general; (2) advocacy of new and stronger governance arrangements is widespread, with some opinion favoring a new world environment organization under UN auspices as the way forward. The core challenge of mitigation, or emissions reduction, would ideally be addressed first by the small number of countries that represent 80 percent of global emissions, represented in the Major Economies Forum (MEF), a sort of climate G-20, rather than through the UN process where close to 200 countries need to be corralled into agreement. After all, the action taken by fewer than twenty countries will determine whether or not global greenhouse gas concentrations can be limited to 450 parts per million [CO.sub.2] equivalent or lower, so that there is an even chance of limiting global warming to 2 degrees above preindustrial levels. The G8 has given useful impetus to global action on climate change, but its role is limited because it is not sufficiently representative of the developing economies. If the MEF did not already exist, inevitably a similar grouping would have emerged sooner or later. This is not to say that a MEF-brokered agreement on reducing global emissions would be enough in itself. The small, the poor, and the vulnerable, who represent numerically by far the largest number of countries, are in a position to demand that their needs be catered to in any future climate agreement. In particular, no agreement can afford to overlook a large-scale response on adaptation for these countries that have contributed little to global emissions and now find themselves at the forefront of expected impacts of climate change. …