Rosenzweig et al published a meta-analysis of "Attributing physical and biological impacts to anthropogenic climate change" in this issue of nature. It is very impressive for two reasons:
1) It is "THE FIRST to formally link observed global changes in physical and biological systems to human induced climate change (Zwiers and Hegerl, the same issue)". The aim of this study is searching for causation, not correlation. To identify causation is notoriously difficult for board scale social-ecological systems, not alone at global scales. How did they do it? By a very interesting approach called "Joint attribution approach". Rosenzweig broken the cause (anthropogenic climate change) and the effect (biophysical changes) chain into two links: first, they showed the biophysical changes were consistent with warming; second, they adopted IPCC's conclusion of warming is likely due to human activities. Put the two pieces together, they got both "attributing" and "anthropogenic" in their title.
2) The paper has a HUGE dataset. It includes > 29,500 data series (only 829 were about physical changes, the rest biological changes) that contains at least 20 years' data during the period of 1970 to 2004. Very few dataset is from Latin America, African and Australia however. China only got sparse data points on its border.
As impressive as this study gets, it doesn't help in convincing those believe in warming but not human-induced warming, i.e. those haven't been converted by IPCC's "90% probability" conclusion. Uncertainty will always be the default and the real question is, how do we make a decision in face of uncertainty.
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