The boreal forests, one of the largest carbon stocks on earth, will not be able to respond to global warming by migrating northwards. Massive forest dieback, causing runaway warming, is a more likely scenario. Under the Kyoto protocol, nations have to account for changes in carbon stock by afforestation, reforestation and deforestation, while leaving old-growth forests intact is not an activity considered to affect the carbon budget. This probably reflects the common perception that old forests do not sequester carbon. They do, according to a new report from AirClim1.