THE hope that forests will soak up the extra carbon dioxide humans emit into the atmosphere has been dealt another blow. Instead, pollutants such as sulphur dioxide could greatly reduce the amount of CO2 trees can consume.
Martine Savard and her colleagues from the Geological Survey of Canada in Quebec came to this conclusion after analysing the ratio of carbon isotopes in the rings of spruce trees near a copper smelter. Trees preferentially use CO2 that contains the common carbon-12 isotope, but if the leaves can’t absorb enough fresh CO2 they are forced to use more…
