PS: Note that the Princeton news release and the IPCC SPM are both referring to emissions rather than accumulations, so they're taking into account that only a portion (roughly half) of the carbon from the CO2 emissions will stay in the atmosphere.

According to IPCC, we'd emitted roughly 515 gigatonnes (metric gigatons) of carbon by 2011. See section E.8, second bullet, page 25, of the WG1 SPM: http://www.climatechange2013.org/images/uploads/WGI_AR5_SPM_brochure.pdf I think Frolicher was including this in his proposed new upper limit--i.e., we only have about 235 gigatonnes left to emit, rather than 485 gigatons. If we're adding roughly 9-10 gigatonnes per year, this implies we might break through the threshold in less than 30 years.

The projected track of Sandy is not just unusual, it's essentially unprecedented. Try going to the link to the NOAA historical database graphing program provided above by Apocalypse4Real. When you plot all tracks of all Cat. 1-5 hurricanes that moved within 200 nm of NYC between 1851 and 1911, you see that all but one was moving from the southwest to the northeast quadrant. The only exception is a Cat. 2 hurricane from September 1903, which had a slight SSE-NNW orentation. There is nothing remotely like the sharp left hook and coastal approach from the SE being predicted for Sandy. Not only is this track indicative of something extremely unusual in the steering flow, it's very problematic for NJ/NY because it'll slam water toward the NY harbor from almost a right angle. It's also giving forecasters fits because there's no real precedent to draw on. The 1991 Perfect Storm is the closest analog to the westward motion and the hybridization process--but of course, it never came close to striking the U.S. coast, and this system looks to be stronger. I fully expect some very unusual consequences. BTW, I'd like to thanks Neven and everyone for this superb blog, which I've been reading for years (and giving an occasional shout-out to from my NCAR AtmosNews/Opinion blog-style columns). I've learned an enormous amount, and I now consider this an indispensible part of my weather/climate news diet. Mille grazie!

@Artful Dodger: Thanks for the kind words and thoughts! We're doing much better here in Boulder today. You can track fire updates here: http://boulderoem.com/emergency-status The fire is almost halfway contained and there's very little smoke visible now, so I think we're out of the (burning) woods for the time being. It's still looking like a long, hot summer, though.

A sign of the times: It looks like Resolute, Nunavut (75°N) set an all-time temperature record on Saturday with 18.7C: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?StationID=1776&Month=7&Day=9&Year=2011&timeframe=2 According to Wikipedia's climate entry for Resolute, that beats the old record of 18.3C set in July 1962. Greatly enjoying this discussion. Thanks for the frequent updates, Neven!