In the future, climate change is likely to play a major role in
the carbon balance of temperate forests and other land ecosys-
tems, although the sign and magnitude of the resulting feedbacks
to the climate system are uncertain (9, 10). The projected warming
of between 1.1 °C and 6.4 °C over the next 100 y (11) could affect
the carbon balance of terrestrial ecosystems by altering bio-
geochemical processes such as plant photosynthesis and micro-
bial respiration (2, 12–14).