Another day, another UN climate change report, another trip to the thesaurus to look up synonyms for "dire." Grim? Daunting? I can't find a good one. The New York Times did a fine job, though, of summing up the ways in which the IPCC may well be underestimating the pace of global warming:

Even though the synthesis report is more alarming than its predecessors, some researchers believe that it still understates the trajectory of global warming and its impact. The I.P.C.C.’s scientific process, which takes five years of study and writing from start to finish, cannot take into account the very latest data on climate change or economic trends, which show larger than predicted development and energy use in China. ...

The panel presents several scenarios for the trajectory of emissions and climate change. In 2006, 8.4 gigatons of carbon were put into the atmosphere from fossil fuels, according to a study in the proceedings of the National Academy of Science, which was co-written by Dr. Klepper. That is almost identical to the panel’s worst case prediction for that year.

Likewise, a recent International Energy Agency report looking at the unexpectedly rapid emissions growth in China and India estimated that if current policies were not changed the world would warm six degrees [Celsius] by 2030 [!?!?], a disastrous increase far higher than the panel’s estimates of one to four degrees by the end of the century.

As best I can tell, the IEA's "six degrees by 2030" prediction is a worst-case scenario—a look at what could happen if the world maintains its present energy course, and China and India keep on growing and burning coal at their current rates. Still, as worst-case scenarios go, it's a pretty fucking, um, dire one.

P.S. Ah. Thanks to commenter mitchell porter, it seems that should be "six degrees beyond 2030"—likely six degrees by the end of the century. Still (very) freak-out-worthy, but not the same as what the Times had.