[1] Alfred Wegener Inst, Helmholtz Ctr Polar & Marine Res, Telegrafenberg A43, D-14473 Potsdam, Germany
[2] Heidelberg Univ, Inst Environm Phys, Heidelberg, Germany
[3] Humboldt Univ, Berlin, Germany
[4] Max Planck Inst Meteorol, Hamburg, Germany
[5] Zentralanstalt Meteorol & Geodynam, Vienna, Austria
[6] US Geol Survey, Alaska Sci Ctr, Anchorage, AK 99508 USA
[7] Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden
[8] Stockholm Univ, Bolin Ctr Climate Res, S-10691 Stockholm, Sweden
[9] Los Alamos Natl Lab, Los Alamos, NM USA
[10] Russian Acad Sci, Inst Physicochem & Biol Problems Soil Sci, Pushchino, Russia
[11] Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA
[12] INRS, Ctr Eau Terre Environm ETE, Quebec City, PQ G1K 9A9, Canada
[13] Univ Illinois, Dept Plant Biol, Urbana, IL 61801 USA
[14] Univ Montreal, Geog Dept, Montreal, PQ H3C 3J7, Canada
[15] Univ Helsinki, Dept Environm Sci, Helsinki, Finland
[16] Lawrence Berkeley Natl Lab, Climate & Ecosystem Sci Div, Berkeley, CA USA