The potential future role of biofuels has become an important topic in energy legislation as it is seen as a potential low carbon alternative to conventional fuels. Hence, future yield growth is an important topic from many perspectives, and given the extensions of the period over which data are available a re-evaluation of yields trends is in order. Our approach is to focus on time series analysis, and to improve upon past work by investigating yields of many major crops in many parts of the world. We also apply time series techniques that allow us to test for the persistence of a plateau pattern that has worried analysts, and that provide a better estimate of forecast uncertainty. The general conclusion from this time series analysis of yields is that casual observation or simple linear regression can lead to overconfidence in projections because of the failure to consider the likelihood of structural breaks.

At The Hague in November 2000, a decade of apparent progress in the climate negotiations seemed to run off the tracks. The precipitating event was the meeting intended to settle the details of the Kyoto Protocol, which ended instead in disarray and recrimination. Though a surprise to many, this was a train wreck that had been proceeding in slow motion for several years, as the European Union, the United States and like-minded nations, and developing countries squabbled over the design and implementation of measures to limit greenhouse gas emissions. Some negotiators and analysts hope that agreement on the details, which seemed so close on the last day in The Hague, can be resurrected. We are not optimistic. It may, in fact, take many more years to put together the kind of effective, grand international deal that was sought in Kyoto, covering both the US-EU sticking points and difficult North-South issues. It is not clear that short-term failure is irreversible, however-or even undesirable,if what replaces the grand deal is a period of national experimentation that can then be knit back together into a more effective international system.
      To prepare for discussion of possible ways forward, we begin with our interpretation of the history of the climate negotiations. We trace the sequence of events from the FCCC signed at the Rio Earth Summit in 1992, through crucial decisions reached in Berlin in 1995 and at the Kyoto meeting in 1997, and finally to the debacle in The Hague. In this process, the negotiators attempted to establish the long-term architecture of an emissions control pact among countries with very different political institutions and economic circumstances, and at the same time tried to set stringent targets for short-term action. They appear to have been too ambitious. The process never dealt adequately with developing country issues, and in setting targets they ran far ahead of domestic support in key countries.
      Against this background, we turn to an exploration of next steps in the international process. One conclusion is that the international discussions need to give serious attention to the prospect that mitigation actions will proliferate and deepen even without common agreement, as nations develop their own definitions, policy measures and market institutions. While modest, but important, short-term actions will proceed on a nation-by-nation basis, the public goods nature of the climate problem means that any meaningful long-term response will ultimately require agreement among nations over burdens and rules. The question then is what, short of a Kyoto-style protocol, can be done now to facilitate consistency later. Clearly, creative thought is needed, perhaps on a less grand scale than in recent years, to guide inevitable mitigation activities in more-or-less coherent directions, in the hope that tighter coordination will emerge.

© 2001 The Royal Institute of International Affairs

Atmospheric fine particulate matter <2.5 μm (PM2.5) can cause cardiovasculatory and respiratory damages and mortalities. Assessing population exposure to and damages from PM2.5 is important for policy, but measurement networks are only available in a few regions. We assess variation resulting from using different sources of concentration information to constrain PM2.5 exposure worldwide, and compare the magnitude of this variation to uncertainties in epidemiological exposure-response functions and economic valuation of health impacts. We find that only 10% of global population is in areas constrained by ground-based data. We calculate and compare regionally-averaged population-weighted concentrations using two atmospheric models: the MIT/NCAR CAM3 aerosol-climate model, and the GEOS-Chem atmospheric chemistry model; and a satellite-derived PM2.5 product. We examine the contributions of different aerosol components to population-weighted PM2.5, and find large differences in exposure between U.S. and global populations. We use the MIT Emissions Prediction and Policy Analysis Health Effects model (EPPA-HE) to assess global health impacts and related economic costs, and conduct probabilistic uncertainty analysis of concentration-response functions. We use these combined approaches to project uncertainty ranges for health impacts and related economic costs from present-day PM2.5. We find large uncertainties in simulated PM2.5, especially globally; the magnitude of concentration variation among estimation methods is comparable to uncertainties in epidemiological functions and economic valuations. We identify major contributors to concentration variation, notably the parameterization of atmospheric dust. We estimate an annual global welfare cost of present-day (2000-2005) PM2.5 of $US 280 billion (range $120 – 510 billion), and related annual mortalities at 1.3 million per year (630,000 – 2.1 million).