The uncertainties re great but so are the certainties. Venus and Mars show what too much, or too little, greenhouse gas can do to the possibility of life. Carbon dioxide's ability to absorb infra-red radiation can be measured. But the analysis of how much warming, what changes in climate, what impact on agriculture, on health and comfort, how well different countries can adapt, is still in progress; too little is known to predict what concentration will be too much, so no global "rationing" scheme is likely. Certainly the worst climate impacts will be on the rural poor; economic development is an important defense. An ambitious program of research, development, and exploration for new economical energy sources and locations for carbon sequestration is urgently needed. The already-developed nations will have to provide financial and technological assistance to the less developed. 　　

　　不确定因素很多，确定性因素也很多。金星和火星可说明温室气体对生命存在可能性有多大或多小的影响。二氧化碳对红外线的吸收能力可以量化，但温室气体对地球如何变暖，气候有那些变化，气候变化对农业、健康和舒适那些影响以及不同的国家如何适应的分析还在进行中。人们还无法预测地球可承受的温室气体的最高浓度是多少，因此也无法制定全球性"配给"方案。毫无疑问，最恶劣气候的受害者将是农村的贫困人口，经济发展是重要的防护。目前迫切需要实施一个宏伟的计划来研究、开发和探索新的经济型能源和碳截存位置。发达国家应向欠发达国家提供财政和技术支持。