Although the amount of atmospheric CO 2 produced from fossil fuel is relatively well known, CO 2 exchange between the biosphere and atmosphere from human activities on the land is highly uncertain.
(the amount of atmospheric CO 2; produced; from fossil fuel) (the amount of atmospheric CO 2; is; relatively well known) (the amount of atmospheric CO 2; known; ) (CO 2 exchange between the biosphere and atmosphere from human activities on the land; is; highly uncertain)
the amount of atmospheric CO 2 the amount of atmospheric CO 2 the amount of atmospheric CO 2 CO 2 exchange between the biosphere and atmosphere from human activities on the land
produced is known is
from fossil fuel
relatively well known
highly uncertain