Global Carbon Dioxide Emissions Scenarios: Sensitivity to Social and Technological Factors in Three Regions

Carbon dioxide emissions from 1990 to 2100 AD are decomposed into the product of four factors: population size, affluence (measured here as GDP per capita), energy intensity (energy use per unit GDP) and carbon intensity (carbon dioxide emissions per unit energy). These emissions factors are further subdivided into three regions: more developed countries (MDCs), China, and the remaining less developed countries (LDCs). Departures from a baseline scenario (based on IPCC, 1992a — the so-called ‘business-as-usual’ scenario) are calculated for a variety of alternative assumptions concerning the four emissions factors in the three regions. Although the IPCC scenario is called a ‘non-intervention’ scenario, it is shown, for example, that large decreases in energy intensity in China or carbon intensity in MDCs are built into the ‘business as usual’ case — and such large changes vary considerably from region to region. We show what CO₂ emissions would look like if each of these four emissions factors projected in the baseline case somehow remained constant at 1990 levels. Certain factors like energy intensity improvements and long-term population growth in LDCs, or GDP growth and carbon intensity improvements in MDCs, are shown to have a big contribution to cumulative global emissions to 2100 AD, and consequently, changes in these projected factors will lead to significant deviations from baseline emissions. None of the scenarios examined in this analysis seems to indicate that any one global factor is clearly dominant, but cultural, economic, and political costs or opportunities of altering each factor may differ greatly from country to country.     

应对不确定性:呼吁建立新的科学政策论坛

科学界和政策界具有不同的目标,这就自然导致了对构成某种变化或现象的"检验"标准的差异,以及用不同的方法去描述不确定性和风险的持性及传达不确定性和风险.这些差异可能损害科学家、决策者和公众之间的有效沟通,同时也限制了科学家所愿意研究的社会紧迫问题的类型.本文主要回顾了一系列处理不确定性问题的方法,阐述了当科学和政策不能很好协调时所可能引起的一些错误.并在此基础上,特别针对解决不确定性问题提出了一些具体建议,包括重构科学规范,建立由科学、政策两方面领导广泛参加的科学政策论坛.