By Steven Goddard
The American Thinker ran an article by Randall Hoven that asked “Was the Arctic Ice Cap ‘Adjusted’? The conclusion is based on the chosen value of concentration of ice in the “pole hole” where the satellite can’t measure due to inclination. See the image below from Cryosphere Today for an example:
The statement from the article below is correct, but slightly misleading because March ice concentration near the pole is always close to 100%
If we add the “pole hole” back to the measured “area,” we would get a downward trend in area due to the change in pole hole size in 1987. If we assume that the pole hole is 100% ice, then the downward trend in March would be 2.2% per decade. But if we assume that the pole hole is only 15% ice (the low end of what is assumed), then the downward trend is only 0.1% per decade, which is not statistically significant. (The corresponding downward trend for “extent” was 2.6% per decade.) It is true that whatever downward trend there is for March is due only to these adjustments (assumed pole hole size and concentration). And whether that trend is statistically significant depends on ice concentration in the “pole hole,” an assumed value.
If you look at essentially any available March concentration maps, you see concentrations near the pole close to 100%. 15% is not a reasonable number to work with, or even 80%.
If we adjust the March area for 100% concentration at the pole hole (below) the area and extent trends agree with each other just as expected.
The title of the article is “Was the Arctic Ice Cap ‘Adjusted’?” I believe the answer is yes. The extent/area data is adjusted – but correctly. Comparing this to “CRUgate shenanigans” doesn’t seem appropriate.