Elmendorf, S.C., Henry, G.H.R., Hollister, R.D., Bjork, R.G., Boulanger-Lapointe, N., Cooper, E.J., Cornelissen, J.H.C., Day, T.A., Dorrepaal, E., Elumeeva, T.G., Gill, M., Gould, W.A., Harte, J., Hik, D.S., Hofgaard, A., Johnson, D.R., Johnstone, J.F., Jonsdottir, I.S., Jorgenson, J.C., Klanderud, K., Klein, J.A., Koh, S., Kudo, G., Lara, M., Levesque, E., Magnusson, B., May, J.L., Mercado-Diaz, J.A., Michelsen, A., Molau, U., Myers-Smith, I.H., Oberbauer, S.F., Onipchenko, V.G., Rixen, C., Schmidt, N.M., Shaver, G.R., Spasojevic, M.J., Porhallsdottir, P.E., Tolvanen, A., Troxler, T., Tweedie, C.E., Villareal, S., Wahren, C.-H., Walker, X., Webber, P.J., Welker, J.M. and Wipf, S. 2012. Plot-scale evidence of tundra vegetation change and links to recent summer warming. Nature Climate Change 2: 453-457.
The authors state that "remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity over much of the Arctic," noting that "normalized difference vegetation index (NDVI) values have increased over the tundra biome in recent years, indicating a greening of the tundra ecosystem coincident with climate warming trends," citing the studies of Pouliot et al. (2009) and Bhatt et al. (2010). However, they say that "plot-based evidence for vegetation transformation is not widespread," a deficiency which they proceed to correct.
What was done
Very simply, Elmendorf et al. write that they "analyzed change in tundra vegetation surveyed between 1980 and 2010 in 158 plant communities spread across 46 locations throughout the Arctic.
What was learned
In the words of the 47 researchers hailing from 12 different countries, "we found biome-wide trends of increased height of the plant canopy and maximum observed plant height for most vascular growth forms; increased abundance of litter; increased abundance of evergreen, low-growing and tall shrubs; and decreased abundance of bare ground."
What it means
Once again in the words of the authors, "our data provide plot-scale evidence linking changes in vascular plant abundance to local summer warming in widely dispersed tundra locations across the globe," as (as we always like to add) the greening of planet earth continues, thanks not only to global warming, but also to the aerial-fertilization and water-use-efficiency-enhancing effects of atmospheric CO2 enrichment.
Bhatt, U.S., Walker, D., Raynolds, M., Comiso, J., Epstein, H., Jia, G., Gens, R., Pinzon, J., Tucker, C., Tweedie, C. and Webber, P. 2010. Circumpolar Arctic tundra vegetation change is linked to sea ice decline. Earth Interactions 14: 1-20.
Pouliot, D., Latifovic, R. and Olthof, I. 2009. Trends in vegetation NDVI from 1 km AVHRR data over Canada for the period 1985-2006. International Journal of Remote Sensing 30: 149-168.Reviewed 21 November 2012