What contributed naval warfare to remarkable winter
and the Arctic sea ice in summer 1917?
Do more than 5000 submerged merchant ships, two extremely winters, and the largest sea ice extent in the North Atlantic (NA) during the entire last Century, in summer 1917, fit together? Yes, at least it is the only convincing explanation for the three extraordinary events. The link is the naval war during the First World War (WWI), causing the extreme cold winter in Western Europe 1916/17, the NA sea-ice in summer 1917, and the record cold winter 1917/18 in North America, by fighting at sea, and U-boats alone could sink several thousand merchant ships from 1916 to 1918 (see Table). Let’s have a look at the three events.
The winter 1916/17 in Europe
All those who lived in Europe through the winter of 1916-17 had memories of the bitterly freezing conditions, notoriously a very, very cold winter (More here) The Turnip Winter occurred during the winter of 1916–1917 in Germany. Continually poor weather conditions led to a diminished harvest, most notably in cereal productions. (More Wikipedia). The French winter of 1916-1917 was the extreme of cold. The bitter winter was the coldest in living memory for soldiers in France and Flanders. Soldiers suffered from frostbite and exposure, causing them to lose fingers (More). In England the winter seasons (December-February) 1916/17 and 17/18 were both cold. One has to go back to 1891 to find an equivalent cold season (Details) The widespread destruction of Bird-life caused by the severe winter of 1916-1917, and more especially by the prolonged period of frost which extended late into the spring of 1917, was so noticeable that it attracted the attention of the least observant ( More)
The link to naval war and ship losses 1916 to 1918
Although WWI started in August 1914, naval war began in earnest only two years later, when a series of new weapons were put in use: sea mines, depth charges, new sub-marines, and airplanes. By then naval warfare had reached a destruction stage to which no one might have thought of only two years earlier. The situation became dramatic when U-boats destroyed more ships than Britain could build in early 1917. In April 1917, the same total rate of the previous annual rate of 1916, ca. 850,000 tons, was destroyed by U-boats. In April 1917, Britain together with the Allies lost 10 vessels every day. During the year of 1917, U-boats alone sank 6,200,000 tons, which means more than 3000 ships, and, during the war months of 1918, another 2,500,000 ship tonnage. The total loss of the Allies ship tonnage during WWI is of about 12,000,000 tons, namely 5,200 vessels. The total loss of the Allies together with the Axis naval vessels (battle ships, cruisers, destroyers, sub-marines, and other naval ships) amounted to 650, respectively 1,200,000 tons.
Naval war and the record summer sea ice extent in the North Atlantic
Since the seasonal sea ice extent is observed since the late 19th Century, it never reached a size as in summer 1917. This year the Arctic sea ice has reached its annual maximum extent on March 13, 2019 (Details) In spring 1917 it started to grow after the average annual peak extension in March/April that lasted well into June. From October 1916 to April 1917 U-boats sunk about 3,5 Mio gross-ton, or about 7 to 8 ships per day. Many thousands other naval activities in the north-eastern NA, as shelling, depth charging, torpedoing, and seas mining have altering the sea conditions as well. Not only the ‘natural’ structure of the sea surface concerning temperature and salinity was affected, but it meant that possibly several hundred thousand tons of dry cargo and from oil tankers, covered huge sea areas for some time, and moved northward with the prevailing sea currents. Little speaks for the assumption, that the growth of sea ice after passing the seasonal peak in April had been a mere ‘natural’ incident. Those who claim so have to explain why, because it happened only once during the last 120 years. A convincing answer could also explain why the following extreme winter caught the east of North America by surprise.