Almost three weeks ago, I wrote a post on the “climate myth” that the “IPCC is alarmist”. I then focused on how an actual statement from Dr. Roy Spencer was changed beyond recognition before it was “debunked” in a skepticalscience article. The climate myth “the IPCC is alarmist” is tackled in their article by the use of four examples. The subject of this post will be the argument of the second example:
[…] By 2100 sea-level rise was predicted by the IPCC to be in the range of 18-59 cm. It is now believed that figure may be far too low, because estimates of contributions from Greenland and Antarctic ice-caps were excluded from AR4 because the data was not considered reliable. (This omission hardly supports the notion that the IPCC seeks to exaggerate global warming trends).
I heard similar claims before. The IPCC is excluding things that it is not sure about, so their predictions could be much more alarmist if they wanted to. Therefor the IPCC is considered “conservative”, “cautious” or “to err on the side of the least drama”.
In this case, if estimates of contributions from Greenland and Antarctic ice-caps were excluded because “the data was not considered reliable”, then it is likely that the sea level rise is going to be faster than projected and then the IPCC isn’t exactly alarmist if they report this number that is too low. At least when it comes to sea level rise.
Well, yes … and no.
Although I can understand that if the IPCC didn’t include these estimates in their report, then sea level could rise higher than expected, I think this is a very narrow interpretation of “being alarmist”. There are many other ways in which the IPCC could be alarmist, even when some of the numbers in the report are underestimated. It is also important how their report is broadcasted and this is were the story changes dramatically.
Looking for how this IPCC sea level rise message is brought in the media, this is the first link that I found: ‘Five Minutes to Midnight’ as Climate Change Endgame Threatens:
Just look at how this starts (my emphasis):
‘Five Minutes to Midnight’ as Climate Change Endgame Threatens
Irreversible sea level rise, mass species extinction just around the corner unless immediate action is taken, warns UN
The world is running out of time -and fast- to take action on climate change UN climate chief Rajendra Pachauri warned this week, stating, “We have five minutes to midnight.”
This article is not an exception. Despite the IPCC “understating” the case on for example sea level rise in AR4, Pachauri succeeded to sound the alarm. He didn’t need the numbers in that report to do so. He didn’t have to mention the exact numbers or their context. He however used words like “endgame”, “threatens”, “five minutes before midnight”, “immediate action” and “running out of time fast”. If this is not “alarmist”, then I don’t know what is.
By the way, this guy was the chairman of the IPCC back them.
What the author of this style of argument ignores is that the IPCC is a political organization and climate science a politicized science, so this behavior is not entirely unexpected.
But above all, their argument misses Spencer’s original point completely, namely that the IPCC is completely focused on human causes and neglects natural causes. That is even a fundamental and systematical OVERstating of the attribution, inherent to its mission.
Trust, yet verify 
The estimate of 18-59cm was from the 2007 AR4. For the 2013 AR5 WG1 the IPCC tried a different approach looking at different emissions scenarios. From Table SPM.2 (from the Summaries for Policy-Makers) they used different emissions scenarios. The most extreme is RCP8.5 (and where they admit in WG3 is unlikely) the range is 45-82cm. The RCP2.6 – keeping temperatures below 1.5C rise – gives 26-45cm of sea level rise. The marginal difference of all the global policy efforts do not seem worthwhile. After all the extra years of trying justify extra sea level rise, thousands of the World’s leading scientists seem to have failed.
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The skepticalscience claim that the estimates may be far too low, was related to the AR4. However, while looking for more background on the issue, I also came across the same claim about AR5. Apparently, the IPCC also failed to include those estimates in AR5 and no upper bound could be given.
When going back to the original skepticalscience article via the Wayback machine, I noticed that the claim back then was related to the Third Assessment Report (TAR) from 2001. Apparently, this criticism has already a long history. It also shows that there is a large uncertainty involved (not mentioned by the doomsayers).
As I said in my post, the IPCC doesn’t need the data from their reports (whether it is TAR, AR4 or AR5) to sound the alarm.
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I am glad to see you have done the research. Projections have not been revised in the light of new research, and the IPCC report largely ignores these projections in sounding the alarm. They do have a fall-back of peer-reviewed articles that back up the claims.
There is a question of uncertainty in predictions. When forecasting over long periods the baseline is to assume that current trends will continue. Satellites give just over 3mm per year, hence the lower end of projections. Then you add in assumptions. On temperature rise gives the higher end of IPCC projections, though the RCP8.5 uses some rather extreme assumptions about emissions rises as well.
To get to the alarmist claims of much higher sea level rises requires further assumptions about the instability of the ice sheets and the uneven spread of warming (e.g. Greenland warming being much greater than the rest of the planet). In terms of these claims, the alarmists do have a fall-back of peer-reviewed articles that back up the claims. A recent was James E Hansen et al. 2015. But given that past predictions of alarmism have failed to materialize, these cannot be viewed as reliable.
Click to access acpd-15-20059-2015.pdf
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