Thomas Fuller on polar-bear-gate at Cliscep

This is an extended version of a comment made at Thomas Fuller’s cliscep article Okay, just one more post on polar-bear-gate… I promise…

There are three things highlighted in the post and the comments that illustrate the Polar Bear smear paper as being a rich resource towards understanding the worst of climate alarmism.

First is from Alan Kendall @ 28 Dec 17 at 9:35 am

But what Harvey et al. ignores is that Susan Crockford meticulously quotes from the “approved canon of polar bear research” and exhorts her readers to read it (making an offer to provide copies of papers difficult to obtain). She provides an entree into that canon- an entree obviously used by many and probably to the fury of polar bear “experts”.

This is spot on about Susan Crockford, and, in my opinion, what proper academics should be aiming at. To assess an area where widely different perspectives are possible, I was taught that it is necessary to read and evaluate the original documents. Climate alarmists in general, and this paper in particular, evaluate in relation collective opinion as opposed to more objective criteria. In the paper, “science” is about support for a partly fictional consensus, “denial” is seeking to undermine that fiction. On polar bears this is clearly stated in relation to the two groups of blogs.

We found a clear separation between the 45 science-based blogs and the 45 science-denier blogs. The two groups took diametrically opposite positions on the “scientific uncertainty” frame—specifically regarding the threats posed by AGW to polar bears and their Arctic-ice habitat. Scientific blogs provided convincing evidence that AGW poses a threat to both, whereas most denier blogs did not.

A key element is to frame statements in terms of polar extremes.

Second, is the extremely selective use of the data (or selective analysis methods) to enable the desired conclusion to be reached. Thomas Fuller has clearly pointed out in the article and restated in the comments with respect to WUWT, the following.

Harvey and his 13 co-authors state that WUWT overwhelmingly links to Crockford. I have shown that this is not the case.

Selective use of data (or selective analysis methods) is common on climate alarmism. For instance

  • The original MBH 98 Hockey-Stick graph used out-of-date temperature series, or tree-ring proxies such as at Gaspe in Canada, that were not replicated by later samples.
  • Other temperature reconstructions. Remember Keith Briffa’s Yamal reconstruction, which relied on one tree for the post-1990 reconstructions? (see here and here)
  • Lewandowsky et al “Moon Hoax” paper. Just 10 out of 1145 survey respondents supported the “NASA faked the Moon Landings” conspiracy theory. Of these just 2 dogmatically rejected “climate”. These two faked/scam/rogue respondents 860 & 889 supported every conspiracy theory, underpinning many of the correlations.
  • Smoothing out the pause in warming in Risbey, Lewandowsky et al 2014 “Well-estimated global surface warming in climate projections selected for ENSO phase”. In The Lewandowsky Smooth, I replicated the key features of the temperature graph in Excel, showing how no warming for a decade in Hadcrut4 was made to appear as if there was hardly a cessation of warming.

Third, is to frame the argument in terms of polar extremes. Richard S J Tol @ 28 Dec 17 at 7:13 am

And somehow the information in those 83 posts was turned into a short sequence of zeros and ones.

Not only one many issues is there a vast number of intermediate positions possible (the middle ground), there are other dimensions. One is the strength of evidential support for a particular perspective. There could be little or no persuasive evidence. Another is whether there is support for alternative perspectives. For instance, although sea ice data is lacking for the early twentieth-century warming, average temperature data is available for the Arctic. NASA Gistemp (despite its clear biases) has estimates for 64N-90N.

The temperature data seems to clearly indicate that all of the decline in Arctic sea ice from 1979 is unlikely to be attributed to AGW. From the 1880s to 1940 there was a similar magnitude of Arctic warming as from 1979 t0 2010 with cooling in between. Yet the rate of increase in GHG levels was greater from greater in 1975-2010 than 1945-1975, which was in turn greater than the period decades before.

Kevin Marshall


Reconciling UNIPCC AR5 polar ice melt data with sea level rise

For over a year I have been pondering how to reconcile the near constant rise in sea levels with the accelerating polar ice melt. At the end of September the UNIPCC published the AR5 Working Group II (the Physical Science Basis) Summary for Policymakers which provides some useful evidence.

The following from the UNIPCC gives some estimates of the rate of polar ice melt. In page 9

• The average rate of ice loss from the Greenland ice sheet has very likely substantially increased from 34 [–6 to 74] Gt yr–1 over the period 1992 to 2001 to 215 [157 to 274] Gt yr–1 over the period 2002 to 2011.

• The average rate of ice loss from the Antarctic ice sheet has likely increased from 30 [–37 to 97] Gt yr–1 over the period 1992–2001 to 147 [72 to 221] Gt yr–1 over the period 2002 to 2011. There is very high confidence that these losses are mainly from the northern Antarctic Peninsula and the Amundsen Sea sector of West Antarctica.

Put in sea level rise terms, the combined average rate of ice loss from the polar ice caps increased from 0.18 mm yr–1 over the period 1992 to 2001 to 1.00mm yr–1 over the period 2002 to 2011.

There is a problem with these figures. The melting ice will end up raising sea levels. The satellite data from the University of Colorado shows a near constant rate of rise of 3.2mm yr–1.

Assuming a one year lag in raising sea levels, the 0.18 mm yr–1 over the period 1992 to 2001 is equivalent to 5% of the 3.3mm yr–1 average sea level rise from 1993 to 2002, whilst the 1.00mm yr–1 over the period 2002 to 2011 is equivalent to 32% of the 3.1mm yr–1 average sea level rise from 2003 to 2012. Some other component of sea level rise must be decreasing. The estimates of the other components are given on page 11

Since the early 1970s, glacier mass loss and ocean thermal expansion from warming together explain about 75% of the observed global mean sea level rise (high confidence). Over the period 1993 to 2010, global mean sea level rise is, with high confidence, consistent with the sum of the observed contributions from ocean thermal expansion due to warming (1.1 [0.8 to 1.4] mm yr–1), from changes in glaciers (0.76 [0.39 to 1.13] mm yr–1), Greenland ice sheet (0.33 [0.25 to 0.41] mm yr–1), Antarctic ice sheet (0.27 [0.16 to 0.38] mm yr–1), and land water storage (0.38 [0.26 to 0.49] mm yr–1). The sum of these contributions is 2.8 [2.3 to 3.4] mm yr–1.

The biggest component of sea level rise is thermal expansion. The contribution from this element must be decreasing. Ceteris paribus, that suggests the rate of heat accumulation is decreasing. This contradicts the idea that the lack of surface temperature warming is accounted for by this heat accumulation.

The problem is that all things are not equal. Thermal expansion of water varies greatly with temperature of that water. On page 10 there is the following graphic

The heat content of the upper ocean increased by around 10 x 1022 J from 1993 to 2010. For 700m of ocean depth I estimate this would be 0.1oC. It is a tiny amount that varies greatly with temperature, as shown by the graph below.

As sea temperature varies greatly according to location and depth, it is possible to hypothesise a decline in the thermal expansion with an increase in heat content. This whilst also accepting that both the rate of rise in the heat content of the oceans has accelerated and the contribution to sea level rise due the increase in heat content has decreased. For example one would just have to hypothesise that the increasing heat content had been predominately in the tropics during the 1990s and switched to the Arctic in the 2000s.

Even this switch is not necessary. There is huge variation between areas of the amount of temperature increase over a twenty year period. Consistent with an increase of 0.1 could have been a decrease in average temperatures in an area of ocean as large as the Atlantic and Indian Oceans combined.

But, what makes this less than credible is that this shift almost exactly offset the estimated increase in the ice melt component. Most likely no-one will try to calculate this, as the data is not there. Even with 3,000 Argo Buoys in the oceans, there is still on average just one buoy per 200,000 km3 of ocean, taking about 25 dips a year. The consensus viewpoint appears the less likely than the view that climate models have an exaggerated belief in the impact of greenhouse gases on average temperatures.

There is an opportunity for some further investigation with the data. But a huge amount of work may not yield anything, or may yield conclusion at odds with the “real”, unknown one. However, the first step is to determine how the UNIPCC calculated the figure for thermal expansion. Hopefully it was more substantial than from the difference between the total sea level rise and the estimates for other factors.


At Bishop Hill Unthreaded michael hart Jun 1, 2014 at 4:13 AM refers to some other variables that determines how warming oceans will affect sea level rise through thermal expansion. So now the list includes.

  • The quantity of heat. (see above)
  • The initial temperature of the water which the heat was applied to. (see above)
  • The initial temperature is in turn related to
  1. Latitude – at mid latitudes there is a seasonal variation temperature variation down to about 300 metres.
  2. Depth
  3. Density variation due to salinity (see pdf page 9)

However, there are local variations as well, due to ocean currents that shift over time.

For these reasons, any attempt at estimating thermal expansion will be reliant on assumptions and estimates. The UNIPCC will have simply estimated the difference between estimated “known” factors – ice melt and land water storage – and deducted from the known sea level rise.

In terms of reconciling polar ice melt to sea level rise, there is something that I missed. According to the UNIPCC, glacier melt has a larger contribution to sea level rise than polar ice melt – 0.76 mm yr–1 against 0.60 mm yr–1. It is quite conceivable – particularly since temperatures have stopped rising – that have glacier melt has effectively ceased or even gone into reverse. Unlike with thermal expansion, there should be estimates available to confirm this.