Recent trends and drivers of regional sources and sinks of carbon dioxide - Sitch, S; Friedlingstein, P; Gruber, N; Jones, SD; Murray-Tortarolo, G; Ahlstrom, A; Doney, SC; Graven, H; Heinze, C; Huntingford, C; Levis, S; Levy, PE; et al. (BIOGEOSCIENCES, 2015)