Warm Atlantic water flows through the Faroe-Shetland Channel into the Norwegian Sea. From there, it continues northward along the Norwegian coast. Some of it enters the Barents Sea; another branch flows into the Arctic Ocean. Variations in temperature affect ecosystems, the extent of Arctic ice, precipitation in Scandinavia, wind direction, and the climate of Northern Europe. This ocean current is of vital importance for understanding the climate, ecosystems, and coastal settlement patterns. The question is: what drives the temperature changes in this current?

The answer is in the wind

This question has been debated for more than a hundred years. In the 19th century, the German mathematician Karl Zöppritz (1838–1885) developed a model showing that wind, over time, could cause vertical circulation in the ocean’s water masses, all the way to the deep sea. The answer lay in the wind: random changes in wind caused random changes in ocean temperature. This wind theory was accepted by scientific consensus. But consensus belonged to the past. Modern science demands that measurements override belief.

The answer is in monitored data

In 1895, Swedish oceanographer Otto Pettersson (1848–1941) proposed an international marine research collaboration. He argued it was necessary to ensure scientific management of marine ecosystems, based on facts and data. By 1899, ICES was established to coordinate North Atlantic marine research. In Aberdeen and Murmansk, scientists began measuring the inflow of warm Atlantic water into the Norwegian and Barents Seas. By 1900, ocean temperature measurements were started outside Shetland and on the Kola Peninsula — now the world’s longest continuous ocean data series.

The answer is in lunar waves

To predict the future, one must start from something predictable. Without predictability, the future remains in darkness. In Sweden, records of herring catch extended back over a thousand years. Pettersson discovered a correlation between herring cycles in the Gullmar Fjord, tides, and the moon’s Saros cycle of 18.03 years. The explanation was that long tidal waves stirred warm and cold-water layers in the ocean. This produced a temperature cycle that influenced herring growth. There was, in other words, a link between predictable lunar cycles and the biological herring rhythm. From this, he could calculate when the next good herring period would occur.

The moon was associated with superstition. Pettersson was dismissed as unscientific. Russian researchers faced similar resistance in the 1960s. The wind theory remained dominant — up until our own time.

The answer is in the tide

By the year 2000, Russian scientists had measured temperatures in the Barents Sea every month for 100 years. The time series resembled a stock market — showing ups and downs in fortune. These fluctuations were indicators of climate shifts in Northern Europe, and of ecosystem growth and collapse. The question of whether these changes were predictable remained unanswered. But predictability was necessary — to forecast future growth and manage the ecosystem.

Every time series has a unique signature. A “fingerprint” revealing the source of its variation. If we can identify the signature of the Norwegian Sea, we can forecast the expected temperature changes in the Barents Sea. The signature was identified using a method originally developed for oil exploration. This method made it possible to trace a chain of events from the moon to Earth’s rotation, to tides, sea temperature, and ecosystem response. The results were first published in 1999. The temperature and ecosystem in the Barents Sea followed periods of about 9, 18, and 75 years — patterns that could be linked back to tides, Earth’s rotation, and the moon.

In 2003, I presented these findings at an ICES conference in Tallinn. The study confirmed moon-driven temperature variations in the Barents Sea. I commented that it was time to give Otto Pettersson and the Russian researchers recognition for their pioneering work.

The presentation led to collaboration with scientists in Aberdeen and Murmansk. Together, we analyzed the flow of warm Atlantic water into the Norwegian and Barents Seas. Over four years, we conducted extensive studies of signatures in sea level, tides, salinity, and temperature at the Faroe-Shetland Channel and the Kola Section. The study confirmed a direct link between Earth’s rotation, tidal waves of 9.3, 18.6, and 74.4 years, and the surface temperature of the Norwegian and Barents Seas.

Figure 1: Periodic variations in the Norwegian Sea at 4 × 18.6 = 74.4 years. Lunar Node Tide (blue), North Atlantic Water (NAW) (green), 1930–2050.

The figure shows identified signature periods of 4 × 18.61 = 74.44 years for the Lunar Node Tide (LNT) (blue) and North Atlantic Water (NAW) temperature (green). NAW has a phase lag of π/2 radians compared to the LNT wave — indicating that NAW is driven by LNT. The stationary LNT period, governed by Earth’s rotation, causes NAW to peak around 1941. From 1941, the temperature cools until 1979. Then comes a new warming period, peaking around 2015. From 2015, a new cooling trend is expected toward 2053.

This pattern matches the history of the Norwegian Arctic cod stock. The biomass peaked around 1945. Cooling toward 1980 led to declining growth and a crisis in the fisheries. The signature forecasted a warming phase toward 2015 and growth in the cod population. Now we expect a new cooling period, similar to what happened in the 1970s.

The answer is in scientific consensus

When the study was published in 2008, I was invited to the PINRO Institute in Murmansk to present the results. During the presentation, I was asked how it would be received in Norway. I replied that this was a topic where facts collided with consensus — and reminded them how Russian researchers had faced resistance in the 1960s. The study was well received and has since been cited by more than 70 scientists.

But resistance came from an unexpected source. Climate had been a natural science topic. Now it was geopolitical. The phrase “scientific consensus” entered the discussion. Climate models predicted accelerating global warming toward 2100. It was claimed that warming could be stopped by halting CO₂ emissions by 2050. In 2020, this was declared “undisputed fact” by three university rectors and ten research directors. But consensus is not a scientific method. The Norwegian academic elite had pushed climate science back to the 19th century.

Nature’s own plans

In 2023, I gave a lecture to skippers and shipowners in the fishing industry. They had been told the ocean would continue warming until 2050. I explained that the Norwegian Sea had started cooling in 2015. They could expect declining temperatures in the Barents Sea — and a cut in cod quotas — just like in the 1970s. Recruitment was already falling. In 2024, alarm bells rang. In 2025, quotas were reduced to 1989 levels.

Figure 2: Temperature observations (blue) from the Barents Sea (75°N/10°E), and AMO index (red).

The figure shows actual temperature measurements from the Barents Sea. The temperature (blue line) reached a minimum in 1987 and a maximum in 2022. Since 2015, the trend has been downward. The Atlantic Multidecadal Oscillation (AMO) (red line) had a minimum around 1979 and a maximum around 2015. AMO has a 70–80-year cycle — matching the 74-year signature period.

The temperature in the Norwegian and Barents Seas still follows the ocean’s propeller. Predictable changes, driven by Earth’s rotation. That means we can calculate future climat, to manage ecosystems.

Post song: The ocean’s heart beats just for you

Reference

1. Yndestad Harald; William R. Turrell; Ozhigin Vlatimir. (2008). Lunar nodal tide effects on variability of sea level, temperature, and salinity in the Faroe-Shetland Channel and the Barents Sea. Deep-Sea Research I.
2. .von Dr. Hans-J. Dammschneider, IFHGK. Arktisches Meereis: Erleben wir gerade den Trendwechsel?