AbstractThe potential impact of an increase in methane emissions from natural wetlands on climate change models could be very large. We report a profound increase in methane emissions from cores of mire peat and vegetation as a direct result of increasing the CO2concentration from 355 to 550 μol mol−1(a 60 increase). Increased CH4fluxes were observed throughout the four month period of study. Seasonal variation in CH4flux, consistent with that seen in the field, was observed under both ambient and elevated CO2. Under ambient CO2, methane fluxes rose from 0.02 μol m‐2s−1in May to 0.11 μol m−2s−3in July before declining again in August. Under elevated CO2methane fluxes were at least 100 greater throughout the experiment, rising from 0.05 μol m‐2s−1in May to a peak of 0.27 μol m−2s−1in July. The stimulation of CO4emissions was accompanied by a 100 increase in rates of photosynthesis from 4.6 (± 0.3) under ambient CO2to 9.3 (± 0.7) μol m−2s−1. Root and
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