Global cooling! A contribution
from the naval war in
the Pacific 1941–1945?

Dr. Arnd Bernaerts
4 min readApr 10, 2021

Earth went through a significant cooling from 1940 to mid-1970s. The Northern Pacific experienced two major climatic shifts during the last century.

One occurred in 1976/77 as discussed by Willis Eschenbach in a post at WUWT on April 09/21, naming it the “Great Pacific Climate Shift”. He did not mention the even greater shift about 35 years earlier, which emerged in the very early 1940th. As any discussion climate change matters should primarily focus on humanly initiated changes, the ist shift around 1940 is of much more interest, as this one may be related to activities at sea, namely the naval war in the Pacific from December 1941 to August 1945. The role of the naval war in the Pacific at the same time is an unexplored issue. Within a very short period of time the belligerent powers amassed a military, aerial, and naval force of an unprecedented scale. Only science of climatology did not take notice although meanwhile there had been seven decades of time available.

The Pacific climatic shifts are observed and assessed by the term ‘Pacific Decadal Oscillation’ (PDO), which is an abstract form of North Pacific sea surface temperature anomalies but does not represent them. See the attached figures. A downward shift occurred very suddenly at about 1942. Something must have turned the physics and dynamics of the North Pacific toward a cooling mood, which produced pronounced patterns of sea surface temperature (SST) anomalies that directly impact weather and climate. This turn also marked the onset of global cooling for the following three decades.

Viewing the Pacific Decadal Oscillation Index (PDO) indicates that a driving mood started soon after 1940, which would fit perfectly into the period of the commencement of naval war in the Pacific after the Japanese ambush at Pearl Harbour on December 7th 1941. From this day on the United States started to organise a naval and airborne force to operate in the Western Pacific with breath-taking dimensions, a huge air bomber force, naval surface vessels, and submarines which alone sank about 1,400 merchant and naval vessels representing a total tonnage of 5.0 million tons. All numbers given are only rough estimates.

The number of submarines increased from a few dozen in 1942 to well above 200 in 1944, during which more than 40 boats where on war patrol simultaneously. The US Navy lost 48 submarines in the war zone of the Pacific. Together with the increasing US surface fleet and the bomber capacity since 1942 total losses for Japan amounted to 10.0 million tons, or about 3,000 vessels including about 110 submarines. Allied material losses were considerably less, but accounted as well to approximately 1,000 ships, and many thousands of aircraft. Alone due to naval activities, one can assume that many millions of shells have been fired, many ten thousand bombs dropped into the sea, many thousand sea mines laid, depth charges released, and torpedoes fired. The number of Japanese sea mines in the Japan Sea seems to have been so effective that US submarines avoided this as area of operation. The US and Allied forces advanced from South and South-East via Singapore, Indonesia and the Philippines before reaching Okinawa in summer 1945, but had been also active further north, e.g. at Midway (06/1942) and the Aleutian Islands (June 1942 to August 1943). For more details and discussion see:

Naval war activities presumably had very substantial effects on temperature conditions in the Western Pacific over several years; it is no longer possible to deny outright that this did not have any impact on the wider Northern Pacific Ocean and the trend as indicated in the Pacific Decadal Oscillation. The decline of the PDO at about 1943 has necessary been caused by the naval war in the Pacific, Atlantic, or Europe alone, but it can neither be excluded that it contributed significantly. Ignoring these facts and connections is in this respect unacceptable.