Click For Photo: https://www.sciencedaily.com/images/2018/08/180821125445_1_540x360.jpg
In a study published online Aug. 20 in Nature Climate Change, the researchers used satellite images taken over the past 30 years to track -- down to a pixel representing approximately 25 square miles -- the ebb and flow of plant growth in cold areas of the northern hemisphere, such as Alaska, the Arctic region of Canada, and the Tibetan Plateau.
The 30-year historic satellite data used in the study were collected by the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer. The data was processed by Boston University, and is hosted on NEX -- the NASA Earth Exchange data archive.
Satellite - Data - Arctic - Climates - Tree
At first, the satellite data showed what they expected -- that as Arctic climates warmed, tree and plant growth increased. After comparing these observations with state-of-the-art climate models developed for CMIP5 -- the Coupled Model Intercomparison Project Phase 5 -- what they discovered next surprised them.
Their data analysis revealed that 16 percent of Earth's vegetated land where plant growth was limited by cold temperatures three decades ago is no longer predominantly temperature-limited today, a result that was not reproduced by the CMIP5 models tested. "Our findings suggest that CMIP5's predictions may have significantly underestimated changes in the Arctic ecosystem, and climate models will need to be improved to better understand and predict the future of the Arctic," said first author Trevor Keenan, a faculty scientist in Berkeley Lab's Earth & Environmental Sciences Area and an assistant professor in UC Berkeley's department of Environmental Science, Policy, and Management.
Keenan - Riley - Satellite - Data - Benchmark
Keenan and Riley used the satellite data to build a new observational benchmark that quantifies the growing expanse of vegetated land in the northern hemisphere. They also estimated changes in the proportion of the Earth's surface where plant growth will no longer be limited by cold temperatures over the 21st century. Keenan and...
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