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SUMMARY: We find no evidence for the high profile claim by the WMO [LINK] and climate science in general that AGW is driving down September minimum and March maximum sea ice extent in the Arctic. It is proposed that all sources of heat, including geothermal heat, are important in the study of sea ice dynamics. In particular, the extensive geothermal heat sources of the Arctic region described in related posts on this site [LINK] [LINK] must be considered instead of an attribution of convenience to AGW that derives from an atmosphere bias in climate science in which all surface phenomena are seen in the context of AGW. As for the Antarctic, no evidence is found of sea ice decline either in the September Maximum or in the February Minimum.  In both of these calendar months we find both extent and area measures of sea ice show a rising trend. An oddity of the results is that September maximum sea ice area is growing while cooling while the February minimum is growing while warming. Such anomalous results further emphasize the importance of geothermal heat in the understanding of sea ice dynamics as explained in related posts [LINK]  [LINK] [LINK].

DETAILS: 

FIGURE 1: TRENDS IN ARCTIC SEA ICE EXTENT AND AREA

FIGURE 2: CORRELATION OF ARCTIC SEA ICE DECLINE WITH GLOBAL WARMING

FIGURE 3: DETRENDED CORRELATION ANALYSIS: ARCTIC SEA ICE DECLINE

FIGURE 4: TRENDS IN ANTARCTIC SEA ICE EXTENT AND AREA

FIGURE 5: CORRELATION OF ANTARCTIC SEA ICE DECLINE W/GLOBAL WARMING

FIGURE 6: DETRENDED CORRELATION ANALYSIS: ANTARCTIC SEA ICE

FIGURE 7: SEPTEMBER 2019 UPDATE#1: NORTH: THE ARCTIC

1. This update was added to the post when 2019 data for the important month of September became available. It is noted that due to the extreme seasonal cycle of sea ice extent, the proposed AGW driven decline of sea ice is measured in terms of its seasonal maximum (March in the North and September in the South) and its seasonal minimum (September in the North and February in the South). These seasonal extremes are highlighted in the Figure 7 above and Figure 8 below. Both the EXTENT and AREA measures of sea ice are presented and analyzed.
2. The data for the Arctic (NORTH) appear in Figure 7 above. The temperature data in this chart are UAH lower troposphere temperatures for the North Polar Ocean. They show statistically significant warming trends along with statistically significant decline in sea ice extent for all calendar months suggesting that the decline in sea ice may be driven by AGW and this apparent inverse relationship is generally interpreted in terms of the assumption that global warming by way of fossil fuel emissions is causing a decline in sea ice extent.
3. In the “EXTENT CORR” column of Figure 7 we find the statistically significant negative correlations between temperature and sea ice extent needed to support the causal relationship that AGW drives the decline in sea ice extent. However, since correlation derives from both shared trends and responsiveness, it is necessary to remove the shared trend effect and isolate the effect of responsiveness and these correlations are shown in the detrended correlation column labeled DETCOR.
4. Here, with a sample size of 40, correlations with absolute value greater than ρ=0.464 can be considered statistically significant at α=0.001 as suggested by Valen Johnson in “Revised standards for statistical significance” [LINK] in which he addresses the state of an unacceptable rate of irreproducible results in published research. At the more commonly used error rate of α=0.01, the lowest correlation for statistical significance in this case is ρ=0.358. Using these criteria we find as follows for the Arctic sea ice extent in Figure 7 above:
5. A decline in March Maximum EXTENT is found along with a statistically significant warming trend but the data do not indicate a corresponding decline in March maximum sea ice AREA. Detrended correlation analysis does not show that the decline in March Maximum sea ice extent can be explained in terms of global warming.
6. Declines in both September Minimum sea ice EXTENT and sea ice AREA are found. However, detrended correlation analysis does not show that the observed sea ice decline in EXTENT or in AREA can be explained in terms of temperature trends as no responsiveness relationship is found.
7. The data for the SOUTH (Antarctic) appear in Figure 8 below. No evidence is found of sea ice decline either in the September Maximum or in the February Minimum. The temperature data in this chart are UAH lower troposphere temperatures for the South Polar Ocean. In both of these calendar months we find both extent and area measures of sea ice show a rising trend. An oddity of the detrended correlation of these rising trends of sea ice with ambient temperature shows the odd result that the September maximum area is growing over a period of cooling while February minimum sea ice extent is growing while warming. Such anomalous results point to the importance of geothermal heat in the understanding of sea ice dynamics as explained in related posts [LINK] [LINK] .

FIGURE 8: SEPTEMBER 2019 UPDATE#2: SOUTH: THE ANTARCTIC

THE EISENMAN 2007 PAPER ON INTERMODEL DIFFERENCES ON SEA ICE EXTENT

Eisenman, Ian, Norbert Untersteiner, and J. S. Wettlaufer. “On the reliability of simulated Arctic sea ice in global climate models.” Geophysical Research Letters 34.10 (2007).  While most of the global climate models (GCMs) currently being evaluated for the IPCC Fourth Assessment Report simulate present‐day Arctic sea ice in reasonably good agreement with observations, the intermodel differences in simulated Arctic cloud cover are large and produce significant differences in downwelling longwave radiation. Using the standard thermodynamic models of sea ice, we find that the GCM‐generated spread in longwave radiation produces equilibrium ice thicknesses that range from 1 to more than 10 meters. However, equilibrium ice thickness is an extremely sensitive function of the ice albedo, allowing errors in simulated cloud cover to be compensated by tuning of the ice albedo. This analysis suggests that the results of current GCMs cannot be relied upon at face value for credible predictions of future Arctic sea ice.

BELOW IS THE ORIGINAL POST FOR THE TIME SPAN 1979-2018 THAT INCLUDES ALL TWELVE CALENDAR MONTHS. 

1. In September 2019, the WMO released a report with an alarming list of climate change impacts [LINK] . Included in the many alarming claims made in the report is an extensive and startling evaluation of the decline in sea ice extent in the Arctic and the Antarctic attributed to anthropogenic global warming (AGW).
2. In the report, the WMO lists six concerns about the AGW impact on polar sea ice extent claiming that : (1) From 1979 to 2019, Arctic summer minimum sea ice extent (September) had declined at a rate of 12% per decade; (2) In each of the years 2015, 2016, 2017, 2018, and 2019, the Arctic summer minimum (September) and winter maximum (March) sea ice extents were lower than the 1981-2010 average; (3) The four lowest values for Arctic winter maximum sea ice extent (March) since 1979 are found in the five most recent years 2015 to 2019; (4) Summer sea ice extent in Antarctica (February) reached its lowest and second lowest extents in 2017 and 2018 respectively; (5) The second lowest winter maximum sea ice extent in Antarctica (September) since 1979 was recorded in 2017. (6) Most remarkably, Antarctic summer minimum (February) and winter maximum (September) sea ice extent in the period 2015-2019 are well below the 1981-2010 average. This surprising result is in sharp contrast with the rising trends for both winter and summer seen in the periods 1979-2018 and 2011-2015. Briefly, a catastrophic sea ice decline is claimed for both poles and the decline is attributed to AGW with the implication that these declines can and must be attenuated by following the UN mandated climate action procedures.
3. In this post we show that the available sea ice data from January 1979 to December 2018 are inconsistent with the claims made in the WMO September 2019 report [LINK] .
4.  Figure 1 shows that Arctic sea ice extent has been in decline in all twelve calendar months and that these decline rates are statistically significant. A somewhat weaker decline is seen in the sea ice area. The difference between extent and area has to do with how the satellite measurement grids are tallied [LINK] . To avoid controversy on the choice of sea ice measure, both extent and area are presented in this analysis.
5. The simple fact that sea ice has been in decline during a time when AGW was in process does not in itself imply that AGW is the cause of the decline. Evidence for such causation must be shown to exist in the data. In Figure 2 we present the correlation between UAH lower troposphere temperature over North Polar Ocean against sea ice extent (and area). If rising air temperature is causing a decline in sea ice we would expect to see a negative correlation between temperature and sea ice extent (and area). And that is what we see in Figure 2 where strong and statistically significant negative correlations are found between temperature and sea ice extent (and area).
6. However, it is known that correlations between time series data arise from both shared trends over the full span as well as from responsiveness of the object variable to changes in the explanatory variable at a given finite time scale. Only the second source of correlation has a causation interpretation. In Figure 3, the correlation derived from responsiveness at an annual time scale is tested by removing the correlation due to shared trends. The detrended correlation analysis presented in Figure 3 paints a very different picture. Although statistically significant detrended correlation is found in six of the twelve calendar months, no correlation is found at an annual time scale between temperature and sea ice extent in the two critical months of seasonal minimum sea ice extent in September (where the strongest decline is seen) and seasonal maximum sea ice extent in March. Therefore, we find no evidence for the high profile claim by the WMO [LINK] and climate science in general that AGW is driving down September minimum and March maximum sea ice extent in the Arctic. It is proposed that all sources of heat must be considered, in particular the extensive geothermal heat sources of the Arctic region described in a related post [LINK] must be considered instead of arbitrary attribution to AGW derived from the bias in climate science in which all surface phenomena are seen in the context of AGW.
7. The corresponding analysis for Antarctic sea ice in conjunction with lower troposphere temperatures for the South Polar oceans is presented in Figure 4, Figure 5, and Figure 6. Here the attribution of observed changes to AGW is much weaker particularly so in light of the trend  values which show overall gain and not loss in sea ice extent and area; and none of the correlations between changes in sea ice extent (and area) and lower troposphere temperature are statistically significant.
8. In light of the above, the claim by the WMO of horrific and alarming impacts of AGW on Arctic and Antarctic sea ice extent are not found to have any basis in the data. An additional consideration is the language and peculiarity of the evidence of AGW impact that appear to indicate a circular reasoning effort to find some kind of peculiarity in the data so that an AGW impact can be claimed. A summary of the WMO statement about sea ice is reproduced below.
9. WMO: Six concerns about AGW impact on polar sea ice extent: (1) From 1979 to 2019, Arctic summer minimum sea ice extent (September) had declined at a rate of 12% per decade; (2) In each of the years 2015, 2016, 2017, 2018, and 2019, the Arctic summer minimum (September) and winter maximum (March) sea ice extents were lower than the 1981-2010 average; (3) The four lowest values for Arctic winter maximum sea ice extent (March) since 1979 are found in the five most recent years 2015 to 2019; (4) Summer sea ice extent in Antarctica (February) reached its lowest and second lowest extents in 2017 and 2018 respectively; (5) The second lowest winter maximum sea ice extent in Antarctica (September) since 1979 was recorded in 2017. (6) Most remarkably, Antarctic summer minimum (February) and winter maximum (September) sea ice extent in the period 2015-2019 are well below the 1981-2010 average. This surprising result is in sharp contrast with the rising trends for both winter and summer seen in the periods 1979-2018 and 2011-2015.

[RELATED POST: WMO 2019]

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