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response modes? What controls the degree and nature of the spatial distributions and interactions of the modes, and how do they co-vary?

It is clear that a more comprehensive understanding of the variability of these patterns on decade-to-century time scales is absolutely essential if we are truly to distinguish between anthropogenic change and natural climate variability, or understand their interaction. If an enhanced greenhouse effect strengthens or phase locks existing natural modes of variability, the study of dec-cen variability and the study of anthropogenic change are inextricably combined. It will be impossible to understand one without the other.