Monday, March 30, 2015

The IPCC Record on Global Warming Temperature Projections

Fig. 1 (click to enlarge)
There is an interesting disconnect among various papers published in the Proceedings of the National Academy of Sciences (PNAS).

One paper found that for each 1°C of global average temperature rise there would, as a direct result, be a 2.3 meter sea level rise (SLR), according to Potsdam Institute.

I read another interesting piece at Skeptical Science, which pointed out, asserted, and argued that the IPCC had historically been quite accurate on its future global temperature rise projections:
As shown above, the IPCC has thus far done remarkably well at predicting future global surface warming. The same cannot be said for the climate contrarians who criticize the IPCC and mainstream climate science predictions.
(Skeptical Science, IPCC Estimates Ok). This raised a flag in my mind because many observers, including me, believe that their recent 3 ft. SLR projections in their 5th Assessment, covering from about now to 2100, are low.

The 1990 IPCC projections of temperature increases are shown in Fig. 1, indicating a temperature rise of about 3°C to about 6°C.

Fig. 2 (click to enlarge)
According to the paper in PNAS, that would equate to a SLR of 6.9 to 13.8 meters (about 22.6 to 45.3 feet) which is in accord with the projection of the software I wrote (see Fig. 2).

The new features in the code are: better control of zone switching (when inland melt zones kick in) and the software now acquiring its data from a mySQL database.

(The zone management algorithms will need some more tweaking, but all in all the C++ program is improving with time.)

The paper in PNAS, linking SLR to temperature rise, indicates as follows:
Greenhouse gases emitted today will cause sea level to rise for centuries to come. Each degree of global warming is likely to raise sea level by more than 2 meters in the future, a study now published in the Proceedings of the National Academy of Sciences shows. While thermal expansion of the ocean and melting mountain glaciers are the most important factors causing sea-level change today, the Greenland and Antarctic ice sheets will be the dominant contributors within the next two millennia, according to the findings. Half of that rise might come from ice-loss in Antarctica which is currently contributing less than 10 percent to global sea-level rise.
(Potsdam Institute, emphasis added; cf. PNAS). To be fair, in the PNAS paper they do not specify a clear time frame concerning specifically when the SLR kicks in following the increase in global temperature (it is still a good fit with my model that generated the graph, because their high end is 45.3 ft. and my model shows ~21 ft. circa 2100, leaving the other half for the next century).

This disconnect, which I mentioned in the first sentence of this post, blurs the reason for scientific research, in the sense of scientific research being something that should be for the public good (The Common Good, 2, 3, 4, 5, 6, 7, 8, 9, 10).

I say that, because we need to know when our lack of knowledge, or our denial, puts the public in danger.

Are you ready for "The Harbor & Port Czar" (The Agnotology of Sea Level Rise Via Ice Melt)?

The next post in this series is here.


  1. agnotology is one wonderful descriptive word.

  2. I added a graph generated by data from a sea level rise software program.

  3. "Nah, it'll never happen. Why just the other day, . . . wait, where's this water coming from - HONEY, did you leave the water running in the sink?! Hold on, let me, swim over to, uh - where, how . . .. [glub,cough, choke] .. ..
    ... .... .HEY! T'row . . me . .. .. th t .. rro[blub,blb]"