In the comments, Laurens Bouwer, of the Institute for Environmental Studies, Vrije Universiteit, Amsterdam, who served as an expert reviewer for the IPCC WGII report, provides the following perspective (Thanks Laurens!):

Thanks Roger, for this discussion. It clearly points the fact that IPCC has not done enough to make an unambiguous statement on the attribution of disaster losses in their Working Group 2 Summary for Policymakers (SPM). This now leaves room for speculation based on the individual statements and graphs from underlying chapters in the report, in particular Figure TS-15, Chapters 1, 3 and 7, that all have substantial paragraphs on the topic.

As reviewer for WG2 I have repeatedly (3 times) asked to put a clear statement in the SPM that is in line with the general literature, and underlying WG2 chapters. In my view, WG2 has not succeeded in adequately quoting and discussing all relevant recent papers that have come out on this topic — see above-mentioned chapters.

Initial drafts of the SPM had relatively nuanced statements such as:

Global economic losses from weather-related disasters have risen substantially since the 1970s. During the same period, global temperatures have risen and the magnitude of some extremes, such as the intensity of tropical cyclones, has increased. However, because of increases in exposed values …, the contribution of these weather-related trends to increased losses is at present not known.

For unknown reasons, this statement (which seems to implicitly acknowledge Roger’s and the May 2006 workshop conclusion that societal factors dominate) was dropped from the final SPM. Now the SPM has no statement on the attribution of disaster losses, and we do not know what is the ‘consensus’ here.