Northern latitudes experiencing larger seasonal changes in carbon dioxide

Nature : A study from the 1990s had suggested that northern latitudes were experiencing larger than expected seasonal variations in atmospheric carbon dioxide. However, criticisms of the study led its findings to be mostly ignored. A new study by an international team of researchers attempted to resolve those criticisms and found evidence supporting the earlier study. The researchers compared atmospheric carbon dioxide levels from aerial measurements collected between 2009 and 2011 with similar measurements taken from 1958 to 1961. The measurements examined the change in carbon dioxide levels during the spring, when many plants end their dormant period and increase their intake of carbon dioxide to fuel photosynthesis. At latitudes above 45° N, the researchers found that the change in carbon dioxide levels was 50% greater in the recent period than it was in the period 50 years earlier. The cause for the increase in absorption is unclear. An increase in nitrogen deposition from industry may have contributed, as may have an increase in young, fast-growth trees, which may offset the loss of old-growth forests.