Warming in Earth's northern latitudes has shifted vegetation zones 250 to 430 miles farther north in the past 30 years, according to a NASA analysis of satellite data. "It's like Winnipeg, Manitoba, moving to Minneapolis-St. Paul in only 30 years," said co-author Compton Tucker of NASA's Goddard Space Flight Center in Greenbelt, Md. Some of the most drastic changes in vegetation are occurring along the Arctic coastlines of Alaska, Canada and Russia, the NASA imagery shows.
"Higher northern latitudes are getting warmer, Arctic sea ice and the duration of snow cover are diminishing, the growing season is getting longer and plants are growing more," said Ranga Myneni of Boston University's Department of Earth and Environment. "In the north's Arctic and boreal areas, the characteristics of the seasons are changing, leading to great disruptions for plants and related ecosystems."
The temperature changes are being driven by an "amplified" greenhouse effect: As concentrations of water vapor, carbon dioxide and methane in the area increase from melting snow and ice, the gasses trap more heat, further warming the Earth's surface, ocean and lower atmosphere. This in turn results in further reductions in polar sea ice and snow. Myneni fears that the greenhouse effect might be amplified to a greater extent as newly uncovered soil thaws, and releases additional carbon dioxide and methane.