There was something else that was odd about the Arctic sea ice volume graph that was used in the Benton lecture of 2018 (see previous post). Besides the ambuigity of the last data point and its weird position relative to the previous data points, there also seemed to be something a bit off at the 2012 data point (the lowest point of the graph). When I tried to overlay the Benton lecture graph over the actual annual minimum volume graph, it seemed that the 2012 data point was situated somewhat lower on the Benton lecture graph than it was in the PIOMAS dataset (the dataset this graph was based on). It didn’t seem to be that much at the time, so I wasn’t initially too bothered about it.
I later decided nevertheless to look into it and digitized the whole graph, instead of just looking at that last data point as I did in previous post. This indeed showed that the 2012 value was somewhat lower in the Benton lecture graph.
It also showed that both graphs are identical until 2009, but there is a small phase-shift from 2010 until 2012:
That means that the complete bottom part of the Benton lecture graph dropped about 300 km3 relative to PIOMAS. Weirdly enough, the 2013 value seems to be unaffected.
This means that the person who fabricated the downwards trend after 2013 used a graph that already went a bit lower than what was observed in reality. After this lowered part of the he graph, it went towards the correct 2013 value (exaggerating that increase by 300 km3) and then it plummeted down ending up close to the 2012 value (instead of rising further as is seen in reality). This accentuating the (already lowered) downward trend even more. The difference between the 2015 value of the Benton lecture graph and reality is about 2300 km3.
Then the big question: why the need for those fabrications at the end of the Benton lecture graph graph? In 2018, there was data available until September 2017, so it would have been possible to add four more data points to that graph.
I think the reason could be rather straight forward. Just look at a comparison that I made between what was shown in the lecture and how the minimum volume data would have looked like back then:
So, if you wanted to convey in January 2018 that the Arctic is prime evidence of irreversible changes in the climate system and that the Arctic would be ice-free by 2022, then which one of the two graphs would you choose to illustrate this narrative? Would you choose the one with the fabricated tail end on the left or the one with the actual data on the right?
via Trust, yet verify
May 9, 2023 at 05:34PM
Iowa Climate Science Education 