The German Navy had 28 U-boats when the war started in August 1914. Their capacity was limited. By February next they had lost 7 U-boats but had sunk 10 vessels with a total tonnage of 20,000. This figure accounted for only 10% of all British losses during the first six months of war. Mines sank double that figure over the same period.
The tonnage available with the Allies and neutral countries was estimated at 40 million tons. By January 1917, 5 million tons had been sunk, but 4.4 million tons were built new.
By the end of 1915 Britain had lost 845,000 tons, 90% of which by U-boats. This is almost two ships per day. At that time 20 U-boats had been sunk. The first depth charge, actually a converted mine that detonated automatically at about 15 metres depth had been deployed in 1915. In June 1915 a new depth charge with 300 pounds TNT or amatol had been developed and was used since January 1916.
REMARK: A similar situation can be assumed in a number of critical sea areas, particularly in the Western Approaches and the Irish Sea. If one assumes that each of the ‘anti-submarine vessels was using one depth-charge per day and was at sea for five hours per day, the waters around Britain were not only ‘stirred’ but ‘shaken’. Actually, many mine sweepers, trawlers were also used as patrol boats and had practically no rest time.
During October 1916 U-boats were able to sink 300,000 tons. The average tonnage sunk during 1916 per month was ca. 190,000 tons.
From August 1914 until December 1916 the U-boats sank 2,200,000 tons. This represented a total number of 1,660 Allies’ vessels. However, this was only one quarter of a further 9 million tons the U-boats had sunk in the next 22 months.
So much extraordinary naval activities around the British Isles was a huge invitation to continental air masses to move freely to England and take reign during winter 1916/17 and bring about successive snow winters from 1916-1918.
Since early 1917 the Allies had introduced the convoy system, whereby naval vessels escorted a number of ships, roughly 20 to 30 ships in a convoy. Sailing in convoy proved quite safe for the ships, although the Germans could put up to 50 boats in operation in July 1917, and built an additional 30 boats per month. The USA had entered the war in April 1917. More than 2,000,000 men were sent to Europe during the coming months.
During the year 1918 until October U-boats sank another 2,500,000 tons, accumulating the total during WWI to 12 million tons. The breakup of this is: about 5,200 merchant ships, 10 battle ships, 18 cruisers, 20 destroyers and 9 submarines. The total loss in naval units, Allies and Axis, was 650 ships (including 205 U-boats) with a tonnage of 1,200,000 tons.
The onslaught by U-boats reached the pinnacle with almost one million tons sunk per month as on April 1917. Although the British Navy was able to prevent hundreds of attacks, real or suspected, the result was not encouraging. Only a mere 11 U-boats could be sunk in four months. New protection measures such as convoying, patrols and a new most promising weapon, depth charges, etc. were regarded necessary.
The availability of depth charges had been scarce in early 1917. Every ship was equipped with only two depth charges. With the beginning of 1918 destroyers got 30 to 40 pieces each as supplies increased. What that meant for the U-boats is outlined in the following feature, and the same ‘story’ could possibly have happened in many dozens cases every day.
While U-boats hunted and torpedoed enemy merchant and naval vessels during the early days of WWI without hindrance, the scenario changed since 1916. They became the hunted and were depth-charged. Thousands of naval vessels steamed the seas around Britain day and night. The experience of U-boat U-72 in May 1918 may illustrate the situation at sea. In early May some 75 depth charges were dropped on the boat by anti-submarine vessels and from an airship. Later a destroyer arrived and attacked U-72 with another 20 charges. This caused a leak in a fuel tank leaving a trail of oil at the sea surface. 24 hours later U-72 was again depth-charged by two naval vessels more than 20 times. A British submarine sank U-72 a few days later.
Another example: U-boats were a problem to the British. In June 1917 its shipping loss rose to over 680,000 tons. For this reason four flotilla leaders, with some 50 destroyers and seventeen submarines were sent to an area stretching from NW of Stornoway, round to the north of the Shetlands and eastwards into the North Sea between the 15 th and 25 th June 1917. The idea was to force the U-boats to the surface and attack them. On sixty-one occasions U-boats were sighted and were attacked twelve times. In practice that presumably meant, that during the operation of 75 naval vessels many hundred depth charges had been dropped, in addition to some shelling. No U-boat was sunk. This episode demonstrates that huge operations in the sea may have taken place, which did not go by without any impact on the sea area. However, these were not accounted for in relation to climate change.
The matter would be worth a detailed chapter but would require some lengths. Although the areas at no time took the centre stage they nevertheless saw immense naval activities and destruction. Particularly the intense encounters in the Barents Sea could have played some role in the strong icing in the high North in February 1915 and the harsh winter in North-West Europe 1916/17. Until early 1915 more than 450.000 tons coal and 90.000 tons weaponry had been shipped to the Russian port Arkhangelsk. Russian and German navies had laid thousands of sea mines, and dozens of minesweepers were permanently in service. U-boats sunk 25 ships in late 1916 and further 21 vessels from April to November 1917.
In the Eastern Baltic Sea many dozen mine fields were laid with some ten thousand mines. Many naval activities took place every day over four years. British and Russian submarines operated successfully. The increasing sea icing over the war years from 1914 to 1918 can be attributed to naval warfare in Baltic waters.
Can the fighting around the British Isles during WWI have caused the sudden warming at Spitsbergen in 1918? That is the main question to be answered by this paper and another paper on sea mining 1914-18.
The value of mean winter temperatures, which match some of those from the record winter 1939/40.
The extraordinary similarity in years of snowfall, time period of snowfall, quantity of snowfall and days of snowfall.
The very extreme three cold winter year ‘package’ 1939-1942; also the three winters 1915-1918 were relatively cold and form a ‘package’ that may serve as an indication for not being ‘necessarily usual’.
How to describe sea mines in action?
This section is an annexe to the previous chapter on War at Sea 1914-18, and aims to increase public awareness to the fact that the war at sea in those days was a force big enough to alter the course of climate. Evidently, by the end of 1918 a Severe Warming occurred at Spitsbergen. The shift was so massive that the whole Northern hemisphere warmed up for two decades. The northern part of the North Atlantic must have experienced a Severe Warming at Spitsbergen. The only external force available that could have caused this event at that time was the war in the North Sea and around the British Isles.
By a number of aspects mines play an important part in ‘changing the sea’ scenario that will be discussed in the following. The number of mines laid, ships sunk by mines and mine sweeping efforts turned every metre of the seas around Britain upside down many times over a short period. Mine warfare in WWI culminated in the building of an engineering masterpiece, viz. the Northern Barrage between the Orkney Islands and the Norwegian coast, which could actually have been ‘the final straw’ to make a Severe Warming happen somewhere further north by the end of 1918. 70,000 mines had been laid since summer 1918. Whether this barrage alone or together with other military activities at sea had made the big shift is not the core question. Accounting all naval means together they had the potential to change the composition of huge sea areas from top to bottom and that should be in focus.
The war at sea from 1914 to 1918 had two phases. The first phase lasted for two years until late 1916. This phase was moderate until the second phase that followed. From late 1916 on, the full potential of sea mines, submarines and depth charges was utilised. The employment of the entire range of destructive means and the time when the Severe Warming at Spitsbergen occurred, lie very close to each other. From all general figures mentioned in the following, presumably two-thirds and more belong to the years 1917 and 1918 and to events in the North Sea and the waters around Britain. The following text concentrates on data from this region.
The North Sea was the main location to lay sea mines. The location and the number of mines laid depended on the anticipated target in view. Some of the main aims for all warring parties were to defend their coasts, coastal travel, ports and naval bases. The Germans laid mines in distant waters to sink merchant and naval vessels serving Britain. The Allies often specifically targeted the German U-boats in the Strait of Dover, the Hebrides, and, most important, the Northern Barrage (see below).
Main minefields in the North Sea were the British East Coast including the Strait of Dover, Helgoland Bight and the Northern Barrage. A rough figure for each of these areas is 50,000 mines. The total number of mines in the North Sea was 190,000 and the total number during the whole of WWI was 235,000 sea mines.
Minesweeping is an activity that stirs and shakes the sea on an unprecedented scale. The ‘stir impact’ on the seas could possibly be even many times higher than the mine laying and the impact of mines that ‘hit a target’ together. Between two sweepers in motion ‘hung’ a sweep wire, with a kite, to cut the mooring rope of the mines. Britain alone had more than 700 minesweepers in permanent operation and the Germans also had a considerable number. Possibly 500 ships swept the North Sea every day, day and night. Admiral Sir R. Bacon responsible for ‘The Dover Patrol’ claimed that between 1915 and 1917 his minesweepers had swept a distance equal to twelve times around the earth. “Minesweepers were constantly being sent further and further afield as new minefields appeared (in 1917), and by the end of the year, over 1,000 miles of coastal waters in Great Britain and Ireland were being swept daily for mines, the work starting at dawn by different sections of sweepers stationed along the coast”.
Due to the destructive force of mines many minesweepers were lost. One example only: On April 14 th, 1916, the trawler Alberta was blown up while sweeping a large German minefield. Undeterred its sweeping mate, theOracle, went alongside the sinking vessel and she was also blown up with the loss of twelve out of fourteen men.
Manifold accounts and analyses about the loss of life at sea and damage and loss of ships exist but any questions concerning the impact on the sea have rarely been assessed. The following two reports may illustrate one aspect of sea mining that could have occurred hundreds of times.
While sweeping was in progress, mines usually detonated far enough astern of the sweeper to be harmful. If countermining occurred, however, a second or third mine might explode under a sweeper with disastrous results.
A classic example of this occurred when a flotilla had been sent to skim a British deep minefield, which had been laid against submarines. The object was to skim the deep field to sweep up any mines that had been caught in shallow depth, and might be dangerous to surface ships. The minefield was large, and roughly covered the area between Rathlin Island and Skye (Northeast Ireland and West-Scotland).
Sweeping began and presently a mine went off in the sweep. Within a few seconds, the sea became chaotic with sprouting plumes of spray and smoke. Each line of mines went off in a succession of terrific detonations until none was left. The entire minefield, deep and shallow, was thus unintentionally and automatically cleared in three minutes!
According to Taffrail, Britain laid about 1,000 mines in the Rathlin Island/Skye area, the Germans also presumably laid an equal number.
Presently a mine went off in the port wing sweep. A second later, two more exploded simultaneously – this time nearer to the ship and obviously not touched by the sweep. Countermining had started. Things were becoming exciting. Everyone looked on in apprehension, wondering where the next explosion would take place.
Thundering upheavals had now passed the ships on the port wing and were coming the line. A moment later a heavy concussion was felt in the bottom of all sweepers, and a huge dome of white water rose close at the stern of the next ship to the Leamington.
Minesweeping continued well after the armistice in November 1918 with 55 different flotillas still operating in June 1919. The British searched over 40,000 square miles until November 1919.
According to the terms of the Hague Convention mines were supposed to lose their danger from the moment they broke from their mooring. In practice one could not take that for granted. Actually, they often remained active and were regarded a danger to shipping and to civilians when swept ashore. Thousands of mines drifted long distances.
Minesweepers (sunk or seriously damaged): 214.
U-boats had been a serious threat to the Allies since 1916. They regarded it paramount to prevent U-boats from leaving the North Sea into the Atlantic. To ‘close’ the northern outlet of the North Sea, about 150 sea miles (ca. 275 km), a long barrage between the Orkney Islands and Norway would be required. Off the Norwegian coast the water is 300 metres deep and the coast off Orkney about 100 metres. Sea currents can reach 3-4 nautical miles/hour. That was a challenge and required the development of a new mine, the MK6, to meet it. The charge consisted of 300 pounds of grade B trinitrotoluol (TNT). The mine itself was supposed to have a destructive radius of 100 feet (ca. 30 m) against submarines. Calculations showed that approximately 100,000 mines should effectively prevent U-boats from passing the line. Actually, only about 70.000 mines were laid until October 1918.
Mines were available by March 1918, laying started. “Shortly after mine laying had commenced mines began to explode prematurely. By counting the explosions it was estimated that between 3 and 4 per cent of 3,385 mines laid blew up”. In the middle section “A” mines were supposed to be laid as follows: 10 rows of mines at 80 feet submergence, 4 rows of mines at 160 feet submergence, 4 rows of mines at 240 feet submergence.
Corresponding rows were laid before the Orkney Islands (section B) and Norway (section C).
When deep level mines exploded, ‘a circle of brown discoloured water was spreading slowly around the vessel’.
July 6 th, a mine had been found on the Norwegian coast in the vicinity of Bergen (Daniels, p.108).
July 14 th, 5,395 mines had been laid in 4 hours and 22 minutes (Daniels, p.109).
Approximately 5% of the mines exploded prematurely – a slight increase over previous statistics.
July 29 th, 5,399 mines laid with 14% of mines going off (Daniels, p.111), at one time even 19% in section C (Daniels, p.112).
August 18 th, 12% of mines exploded prematurely.
Section A; mines which had been laid in this area by the British in March 1918, had in the meantime been swept up. (Daniels, p.115).
September 29 th, the Norwegian Government said that mines would be laid in the vicinity of Udsire Island, and it is understood that this had been done by October 07 th (Daniels, p. 119).
With the signing of the armistice on November 11 th, the building of the mine barrage ended. (Daniels, p.120).
Final Status of Barrage (extract): up to November 11 th a total of 56,760 United States and 16,300 British mines have been laid. Completion of the barrage within the Norwegian territorial waters had been effected by Norway herself.
rest 20,000 were swept in 1919.
Six months of sweeping operation comprised seven sweeping missions involving more than 70 vessels and 10 supply vessels.
Before closing this section, a final excerpt from Daniels’ report: In December 1918 it was regarded necessary to determine the actual condition of the mines in the barrage. Two small wooden sailing vesselsRed Rose and Red Fern were chosen to cross the field. On December 22 nd, “a few minutes before noon, as the vessels crossed the first line of invisible mines, a giant column of discoloured water sprang high into the air close astern of Red Rose. The first mine of the North Sea barrage has thus been swept”.
The Norwegian coastal current begins in the Skagerrak, about at the position58° 45’North and 10°00’East, with water from the Oslo Fjord and Kattegat and follows the coastlines of Norway. The coastal current’s speed varies between 0.5 and 1.3 nautical miles per hour (nm/h) and would have crossed the area of the Northern Barrage.
The Norwegian Current, as the extended arm of the Atlantic Gulf Current has a higher speed than its original with about 0.4 and 1.2 nm/h.
If taken a medium speed (ca. 0.8 nm/h), sea water would flow from Scotland to the North Cape in about 35 days and to Spitsbergen in about 45 days.
Together with other war at sea means the sea mines warfare played a considerable role. It has been outlined in a previous chapter the war at sea impact cooled Britain down from 1915 to 1918. With excessive snow generation during these war years, a major change could also have happened in the seawater body that generated a Severe Warming at Spitsbergen. After all, 200,000 sea mines, are more than a drop in the ocean.
Footnotes are not reproduced – Consult the original book text.