Never has such a high sea ice extent been observed in the North Atlantic as in summer 1917 (Fig.1a-1b). This exceptional case has never been investigated. Worst! Science seems not to have taken notice of it, even though thorough understanding of the event could possibly answer two important questions concerning climate change: FIRST: Contribute the late icing and subsequent melting process to the sudden extraordinary warming at Svalbard and polar region since winter 1918/19, (Fig.2)? SECOND: Contributed the naval war around Great Britain from1914 to 1918 (Fig. 3) to the exceptional icing, which lasted until 1939/40 (Fig. 4)? [A detailed WWI account –HERE]
Although air temperatures at Svalbard fell to all-time record low in winter 1917, sea ice conditions in March were usual (Fig. 1a). In general annual sea ice extent is highest in April, but succeeded average already in April 1917, but continued to rise to an unknown high level in May and June of 2017, which presumably has not happen for more than 200 years or longer. Even in late July the sea ice remained at an unusual high level. This late and extensive icing process may have had a pronounced impact and ocean water structure, from sea level to may hundred meter depth, which could have influenced the most significant climatic change in the 20th Century, namely the Arctic and Northern Hemisphere warming that started 18 months later in winter 1918/19 (Fig. 4).
Interesting that Willis Eschenbach observed a significant temperature discontinuity in the Northern North Atlantic at Vardo/Norway (Fig. 5) between 1917 and 1920. But he offers no explanation, neither mentions the naval war in Europe, nor the exceptional sea ice in summer 1917. A pity, the climatic developments in the North Atlantic during WWI could teach climate sciences many important lessons.