4 June 2016, Climate News Network, Warming turns northern tundra green. Rising temperatures are creating longer Arctic growing seasons and increasing the risk of carbon escaping into the atmosphere from the thawing permafrost. The northern edge of North America is getting steadily greener. In the most detailed study so far of plant growth across Alaska and Canada, scientists say that about a third of the land cover now looks less like tundra, and more like a warmer ecosystem. The researchers report in the Journal of Remote Sensing that examination of 87,000 images captured by the NASA Landsat satellite reveals that Alaska, Quebec and other regions became greener between 1984 and 2012. Landsat, a project also backed by the US Geological Survey (USGS), provides the longest space-based record of land vegetation in existence. Growing in size “The greening trend was unmistakable,” the scientists report. In Canada, northern forests tended to become greener, although if anything they declined in Alaska. Overall, 29.4% of the region became greener, and only 2.9% declined. The Arctic is the fastest-warming region of the northern hemisphere, with longer growing seasons and thawing permafrost. The scientists saw grassy tundra convert to shrubland, and shrubs grow in size and density, and such changes will inevitably start to play into water, energy and carbon cycles. Read More here
2 June 2016, The guardian, Spike in Alaska wildfires is worsening global warming, US says Report from US Geological Survey says northern wildfires must now be seen as significant driver of climate change, not just a side-effect. The devastating rise in Alaska’s wildfires is making global warming even worse than scientists expected, US government researchers said on Wednesday. The sharp spike in Alaska’s wildfires, where more than 5 million acres burned last year, are destroying a main buffer against climate change: the carbon-rich boreal forests, tundra and permafrost that have served as an enormous carbon sink. Northern wildfires must now be recognised as a significant driver of climate change – and not just a side-effect, according to the report from the US Geological Survey. “This is one of the surprises that we haven’t talked about much,” said Virginia Burkett, chief climate scientist at the USGS. “It has tremendous implications for the carbon that is locked up in Alaska soils and vegetation.” A record wildfire year – such as 2015 which was the worst in Alaska for a decade – had a measurable effect on the release of carbon dioxide and methane, which are the main drivers of climate change. “Our scientists found that the balance of carbon storage versus release in Alaska was strongly linked with wildfires,” Burkett said. “In years where there was high wildfire activity the net carbon balance declined dramatically, and then it would rebuild in the absence of fire.” Alaska is a far bigger storehouse for carbon than the lower 48 states, according to the USGS. The state’s boreal forests, peat-rich tundra, and permafrost hold about 53% of US carbon. Alaska accounts for about 18% of US land mass. Alaska currently absorbs about 3.7m tonnes of carbon a year, the USGS assessment found. But that vast storehouse of carbon has been breached by warming temperatures, thawing permafrost – and wildfire. Read More here
