New Scientist reports on human activity's impact on another greenhouse gas, nitrous oxide:
As a greenhouse gas, N2O is 296 times as powerful as carbon dioxide and accounts for 6 per cent of the greenhouse effect. To better understand the N2O output from forests, Klaus Butterbach-Bahl of the Karlsruhe Research Centre in Germany and team members Per Ambus and Sophie Zechmeister-Boltenstern studied N2O emissions from 11 European forests...
They found that nitrifying soil bacteria thrive on high nitrogen levels, producing mainly nitrates, which are turned into N2O by denitrifying bacteria. As human activity adds more nitrogen to the biosphere, the production of N2O by the bacteria looks set to grow.