Arctic tundra greening and browning by continent and latitudinal subzone

Howard Epstein, University of Virginia, hee2b@virginia.edu (Presenter)
Leah Reichle, University of Virginia, lmr8ws@virginia.edu
Coleman Dickerson, University of Virginia, csd7yw@virginia.edu
Uma Bhatt, University of Alaska, Fairbanks, usbhatt@alaska.edu
Donald Walker, University of Alaska, Fairbanks, dawalker@alaska.edu
Martha Raynolds, University of Alaska, Fairbanks, mkraynolds@alaska.edu

Until recently the scientific literature has seen an abundance of papers describing the “greening” of the Arctic; from a remote sensing perspective this has meant an increase in the Normalized Difference Vegetation Index (NDVI), or a similar satellite-based index. More recently, there have been more widespread observations of tundra “browning.” Here, we use a circumpolar remote sensing dataset to evaluate the spatio-temporal patterns of arctic tundra vegetation dynamics (greening and browning), and its control by summer warmth, at the circumpolar, continental (North America, Eurasia), and tundra subzonal (i.e. latitude) scales over the past 35 years. Significant warming trends, significant greening trends, and significant inter-annual relationships between NDVI and summer warmth were not spatio-temporally consistent. Significant warming trends tended to occur further north, whereas significant greening trends tended to occur more in the southern tundra. Some significant browning trends were observed in the northern tundra subzones. Significant relationships between NDVI and SWI were more likely found in the middle tundra latitudes. Over the satellite record, the number of years of greening was similar to the number of years of browning, with the exception of the most southern tundra subzone (Subzone E). The spatio-temporal dynamics of tundra vegetation and the controls on greening and browning appear to be highly complex and in need of continued study.

Associated Project(s): 

• Epstein-01

Poster Location ID: 39

Session Assigned: Vegetation Dynamics and Distribution