I have tried to make it quite clear a few times that regardless of no new record, there is no evidence that the underlying rising trend in global surface temperatures has reversed or stopped. But absent a short term rising trend the inattentive public is very vulnerable to disengenouous denialists claiming warming is over (did they ever admit it was happening??). So I am afraid that that talking point will not go away until 1998′s record status does so as well.
So when will that happen? I’m not talking about statistically insignificant 0.05oC win by a nose in one record but not another, I mean when will we get an unequivocal, unanimously agreed replacement of 1998 as the new record high global average temperature?
Being just a blog scientist, and not a real one, I won’t do the actual work needed to answer that question. But there is a real answer, there is a point at which it becomes very unlikely that we won’t have a new record, a point at which the slow, inexolerable underlying climatic trend finally rises above the erratic and rapid weather noise that created 1998′s extreme record.
The bottom line is that it is not surprising that we have not broken that record. 1998 was a very strikingly high record, 2.6 standard deviations above the underlying trend, where the most likely reading would have landed. Given that crucial fact, it turns out that 2008 was actually the year with the highest probablity of breaking the record. In other words “global warming stopped for ten years” was exactly what was the most likely outcome if global warming never stopped!
It will take us until 2012 before we should be scratching our heads and wondering why no new record yet. That is where the 95% probability threshold is (actually this holds whether you take Hadley’s 1998 record or GISS’s les dramatic 2005 record). And that is of course only if there is no identifiable mitigating factor, like some large volcanic eruptions or an actual decrease in solar output.
Of course it may happen before that, in fact that is more likely. We do have an El Nino on the way, (though not one to rival 1998) so maybe it will be this year or the next. But if it isn’t, that does not mean what the denialists will claim it means!
Go have a read at Tamino’s, and let’s all put this talking point to bed until 2012.