On page 10 of the SPM, the IPCC states, in large text in a highlighted box:

Most of the observed increase in global average
temperatures since the mid-20th century is very
likely due to the observed increase in anthropogenic
greenhouse gas concentrations.12 This is an
advance since the TAR’s conclusion that “most of
the observed warming over the last 50 years is likely
to have been due to the increase in greenhouse gas
concentrations”. Discernible human influences
now extend to other aspects of climate, including
ocean warming, continental-average temperatures,
temperature extremes and wind patterns (see
Figure SPM.4 and Table SPM.2).

However, turning to Table SPM2, the evidence seems distinctly shaky, especially if we read the small print. Table SPM2 indicates the likelihood of a human contribution to the observed trend, and describes this as being "more likely than not" for heat waves, heavy precipitation events, tropical cyclones and high sea levels.  Note that "more likely than not" means an estimated probability of > 50%.  Furthermore, these entries in the table are marked with a superscript 'f', and below the table this is explained in the small print as meaning: "Magnitude of anthropogenic contributions not assessed. Attribution for these phenomena based on expert judgement rather than formal attribution studies."  Thus the IPCC has no scientific evidence whatsoever to support the claims of human influence on these other aspects of climate, merely the opinions of the IPCC authors.  Policymakers who focus attention on the large boxed text without reading all the footnotes will be misled. 

[The footnote 12 reads: "Consideration of remaining uncertainty is based on current methodologies"]