I must be really important because Glenn Reynolds has made a specious attack on me based on something I wrote, not in a post, but in a comment on another blog. I wrote that the sea level projections in the draft AR4 report were similar to those in the previous report. Reynolds:
Number problems for Tim Lambert? Color me unsurprised.
He links to Tim Blair, who cleverly quotes me like this:
Lambert looks for a way out: “I didn’t say the numbers were the same, merely similar.” The numbers in question are … 59 and 88.
No, those aren’t the numbers in question. Blair left out my next sentence: “And the comparison is 59cm + extra from accelerating ice flows versus 88cm.” Now I don’t think that Blair was being deliberately deceitful here, but it’s clear he has no clue what is going on in the comparison. The team at RealClimate (several of whom were AR4 authors) explains
Note that some media have been comparing apples with pears here: they claimed IPCC has reduced its upper sea level limit from 88 to 59 cm, but the former number from the TAR did include this ice dynamics uncertainty, while the latter from the AR4 does not, precisely because this issue is now considered more uncertain and possibly more serious than before.
So if you want to compare apples to apples you have to add the numbers for increased ice flows to 59cm. The AR4 SPM reports:
Models used to date do not include uncertainties in climate-carbon
cycle feedback nor do they include the full effects of changes in ice
sheet flow, because a basis in published literature is lacking. The
projections include a contribution due to increased ice flow from
Greenland and Antarctica at the rates observed for 1993-2003, but
these flow rates could increase or decrease in the future. For
example, if this contribution were to grow linearly with global
average temperature change, the upper ranges of sea level rise for
SRES scenarios shown in Table SPM-2 would increase by 0.1 m to 0.2
m. Larger values cannot be excluded, but understanding of these
effects is too limited to assess their likelihood or provide a best
estimate or an upper bound for sea level rise.
Now 0.2m is 20cm, and 59cm + 20cm is 79cm, which is similar to 88cm. But larger values cannot be excluded and the IPCC cannot provide an upper bound for sea level rise. And let’s be clear on this: neither 59cm nor 79cm is an upper bound on sea level rise in the new IPCC report — they don’t know enough to give an upper bound.