How does more carbon dioxide in the atmosphere affect plant growth ?
• How does farming affect climate change ? The unpredictability of increasing atmospheric carbon dioxide 5, both on global climate and on global ecosystems, makes it impossible to answer these questions. Global warming 3 is a grand experiment whose outcome no one can predict. While it is true that increased carbon dioxide levels in the air will increase plant growth (photosynthesis 4), it is impossible to extend such research findings to the response of large-scale ecosystems, be they natural or agricultural. Biomass production at the ecosystem scale depends heavily upon climatic factors. In principle, plants grow faster and produce more biomass in atmospheres containing higher carbon dioxide levels, but what effect will global warming have on rainfall? Even if global warming were not a concern, growing populations will unquestionably place growing demand on limited water supplies. What effect will unpredictable changes in climate and rainfall have on the response to growing demand for
