Some researchers may be getting closer to ‘attributing’ a global warming/severe weather event connection, Nature reports. But challenges are seen as substantial, and ‘absolute confidence’ in fingerprinting will likely remain elusive.

For some it’s the veritable Holy Grail of climate and weather research — the ability, as of now not yet realized — to make a link between climate change/global warming and this or that severe weather anomaly … or a pattern of successive severe weather events, such as much of the U.S. has experienced throughout 2011.

Pointing to most climate scientists’ reluctance to make those connections, a new Nature news report finds that “that reluctance has started to fade.”

“Attribution of extremes is hard — but it is not impossible,” the article quotes NASA/GISS climate modeler Gavin Schmidt as saying. Schmidt, a principal in the realclimate.org website, pointed to advances in statistical tools, climate models and computing power and told Nature “my thinking has evolved.”

The Nature article also points to efforts by American and British climate researchers in forming “ACE — Attribution of Climate-related Events” to help systematically attribute weather events.

“Ultimately, the group hopes to create an international system that could assess the changing climate’s influence on weather events almost as soon as they happen or even before they hit, with results being announced on the nightly weather reports,” Nature reported. The article outlines the interest in such science-based attributions among insurers and civil engineers, for instance, and said improved understanding “is also important for the public’s understanding of climate change, and to their willingness to support measures to reduce greenhouse gas emissions.” But it added that such attributions remain “no simple task.” It outlined an approach labeled as “fractional attribution” aimed at showing “how much” of a particular anomaly resulted from human-caused warming and how much from natural cycles. It noted too that such analyses in some cases are likely to “exonerate” anthropogenic climate change.

The ACE group is expected to soon issue a white paper outlining its efforts.

Along with the news article, Nature on September 7 also posted an editorial commending as a “good sign” the ACE effort to “quickly and routinely assess” the climate/weather connections. With sufficient caveats, that editorial said the effort could help daily weathercasters and their audiences better understand the consequences of a warmer climate. The editorial cautioned also that the attribution “is only as good as the models and statistics that power it” and said “Not even the most thorough study can work out with absolute confidence the exact fingerprint of global warming in a given weather event.”

Less enthused about the ACE initiative, Georgia Tech climate scientist Judith Curry blogged that the ACE group’s use of climate models in its exercise concerns her. Her posting had prompted more than 180 responses as of September 9, providing further grist for the mill for those interested. Curry, in her blog, expressed preference for a NOAA Boulder group. “They no longer refer to it as ‘attribution’ but rather as ‘interpreting climate conditions,’” Curry blogged.