### Instruction:

Extract the cause and effect entities from the following sentence:
In addition, it is stated that without accounting for historical land cover changes, observed atmosphere CO2 growth cannot be explained (Brovkin et al

### Assistant:

NOT_RELEVANT: (Brovkin et al
NEGATION: cannot
VARIABLE: observed atmosphere CO2 growth
CONDITION: be explained
CAUSE_1: without accounting for historical land cover changes
EFFECT_1: observed atmosphere CO2 growth cannot be explained

