On a previous post (here), I linked to a recent study positing that variations in Barents Sea ice extent are predictive of Arctic extent for at least 1-2 years later. In other words, they concluded based upon measurements of ice extent and ocean heat transfers: As winter ice extent goes in Barents Sea, so goes annual ice extent across the Arctic ocean. The physical cause is changing fluxes of warm North Atlantic water penetrating through the Barents Sea into the rest of the Arctic. They acknowledge that other factors, especially winds are also in play, but believe that the ocean influx (also affected by winds) makes the largest influence. The full study is here.
Arctic Ice Dynamics
Here’s how researchers are connecting the dots:
NAO (North Atlantic Oscillation)► BSO(Heat transport by Atlantic Water (AW) through Barents Sea Opening)► Winter ice extent in Barents Sea► Winter ice extent in Arctic Ocean► Annual ice extents in Barents and Arctic Ocean.
A key scientist in this work is Randi Ingvaldsen of Geophysical Institute, University of Bergen, Institute of Marine Research. Several of her published articles are part of her doctoral thesis available here. It comprises an informative look into the extensive body of research in this area.
The Barents Sea climate fluctuates between warm and cold periods. By comparing decade by decade we found that although the 1990s had high temperatures, both the 1930s and the 1950s were warmer. This indicates that the warming of the 1990s may very well be related to natural variability rather than anthropogenic effects.
The above results indicate a positive correlation between the NAO winter index and the area occupied by AW, a result clearly evident when investigating the total area across the BSO occupied by AW (Figure 6d). Earlier investigations have shown a positive correlation between the NAO winter index and the mean AW temperature in the BSO (also evident in
Figure 6e). This means that both the temperature and the extent of AW increase with increasing NAO winter index (Figure 6 a and d-e), although with different lags.
In summary, this preliminary investigation has shown that both the mean temperature and lateral extent of AW in the BSO is positively correlated to the strength of the Icelandic low, although with lags.
The extensive bibliography in the linked studies shows that these results are built upon the efforts of many researchers over decades. There are many references to empirical research efforts in recent times (e.g. an array of moorings in the NE Barents Sea):
The pathway and transformation of water from the Norwegian Sea across the Barents Sea and through the St. Anna Trough are documented from hydrographic and current measurements of the 1990s. . .The westward flow originates in the Fram Strait branch of Atlantic Water at the Eurasian continental slope, while the eastward flow constitutes the Barents Sea branch, continuing from the western Barents Sea opening.
In earlier decades, the Atlantic Water advected from Fram Strait was colder by almost 1 K as compared to the 1990s, while the dense Barents Sea water was colder by up 1 K only in a thin layer at the bottom and the salinity varied significantly. However, also with the resulting higher densities, deep Eurasian Basin water properties were met only in the 1970s. The very low salinities of the Great Salinity Anomaly in 1980 were not discovered in the outflow data. We conclude that the thermal variability of inflowing Atlantic water is damped in the Barents Sea, while the salinity variation is strongly modified through the freshwater conditions and ice growth in the convective area off Novaya Zemlya.
The evidence says Arctic ice varies from a variety of natural factors:
Based on these observational data, Polyakov et al. (2003) concluded that the “examination of records of fast ice thickness and ice extent from four Arctic marginal seas (Kara, Laptev, East Siberian, and Chukchi) indicates that long-term trends are small and generally statistically insignificant, while trends for shorter records are not indicative of the long-term tendencies due to strong low-frequency variability in these time series, which places a strong limitation on our ability to resolve long-term trends”. “Correlation analysis shows that dynamical forcing (wind or surface currents) is at least of the same order of importance as thermodynamical forcing for the ice extent variability in the Laptev, East Siberian, and Chukchi Seas. Source: http://www.climate4you.com/
As with everything else in the climate system, Arctic ice dynamics are complex and our understanding is growing but still incomplete. And like the rest of the climate system, the more we learn, the more evident it is that fossil fuel emissions have little to do with it. We should take seriously other ways humans impact the climate system, be it from our use of the seas, as Dr. Bernaerts points out, or from using the land, as Dr. Pielke has documented.
There’s no denying climate change. Climate is changing: Not much; Not quickly; And not lately. (Credit: David Siegel here)
Footnote November 16:
Some additional reflections:
This line of Arctic ice research is interesting because it challenges typical thinking about northern climates such as Barents.
Firstly, it goes beyond simplistic, value-laden notions, such as “less Arctic ice is a bad thing” (popular), or “less Arctic ice is a good thing” (not popular). These researchers are not making those judgments but are asking a purely scientific question: Why? Why is there more ice some years and less ice other years? And they know that any explanation is tested by how well it predicts future ice extents.
Secondly, this line of research requires a shift in focus from the summer melts in August-September, to pay more attention to the action in the winter, especially December-April. The proposed mechanism of heat transfer by means of Atlantic water happens almost entirely in that time frame, when most people leave the Arctic alone in the dark.
Finally, there is humility in making the predictions, recognizing the complexity of the situation, and how effects lag in time. Certainly, the lack of ice in Barents this last April is a basis for thinking extents there and across the Arctic will be down next April. But there happens to be a cold Blob of surface water in the North Atlantic presently, and that may affect the result. That is the way of science: make predictions, make observations and adapt the theory accordingly.