The assumption that plants can absorb excessive fossil fuel emissions containing carbon dioxide because they need the gas in order to grow is challenged in this paper.These researchers report that increased levels of carbon dioxide (when combined with the other effects of climate change) actually suppress growth rather than helping plants to flourish. The three-year field experiment was unusual in looking at the effects of temperature, rainfall and nitrogen deposits, as well as carbon dioxide, in an attempt to mimic future climate conditions as accurately as possible. The researchers found that while increases in carbon dioxide alone did indeed encourage plants to grow, when combined with these other factors it consistently dampened growth. One hypothesis for the reason behind the suppressive effect of this combination of factors is that excess carbon in the soil allows microbes to out-compete plants for nutrients. The implications of this study for future experiments are that in order to understand complex ecological systems, the traditional approach of isolating one factor and looking at that response, then extrapolating to the whole system, is often not correct. For the wider public, these findings suggest that we shouldn't rely on increased plant growth to counteract emissions of carbon dioxide: the rationale for employing forest 'carbon sinks' to mitigate climate change. [adapted from SciDev and authors]