How Century-Old Maritime Logbooks Are Helping Scientists Predict the Next El Nino

The United Nations' recent warnings about a newly intensifying El Nino phase have sent climatologists scrambling to refine their predictive models. But to understand how the Pacific's warming currents will behave in a modern, greenhouse-gas-heavy atmosphere, researchers are turning to a surprising source: a century-old British research vessel.[1][5]

A hundred years ago this month, in June 1926, the Royal Research Ship William Scoresby launched from Humber Dock in Hull, England. Built specifically to explore the harsh environments of the southern oceans, the ship embarked on a series of grueling voyages that would inadvertently lay the groundwork for modern climate science.[1][5]

El Nino is a natural climate phenomenon characterized by the warming of surface waters in the eastern Pacific Ocean, specifically along the equator. This warming disrupts normal atmospheric circulation, triggering extreme weather globally—from severe droughts in Australia to catastrophic heavy rainfall in South America.[7]

During a grueling 19-month expedition in the 1930s, the crew of the William Scoresby meticulously measured the Humboldt Current—the cold-water current off the coast of South America—and its warm-water counterpart, El Nino. According to researchers at the University of Hull, the physical measurements taken of these deeper ocean layers provided the first accurate delineation of the currents.[1][6]

Why does century-old data matter today? Modern climate models rely on establishing a baseline—a record of how the Earth's systems behaved before widespread industrial carbon emissions altered the atmosphere. The Scoresby's precise oceanographic readings offer a rare, high-fidelity snapshot of the Pacific's natural variability.[1][7]

The ship's legacy is doubly significant because of its namesake: William Scoresby Jr., a 19th-century English whaling captain, clergyman, and scientist. Born in 1789, Scoresby Jr. was a pioneer in his own right, making some of the earliest systematic observations of Arctic temperatures, terrestrial magnetism, and sea ice.[4]

In the early 1800s, Scoresby Jr. used a custom-built ten-gallon fir cask to measure ocean temperatures at various depths. He made the groundbreaking discovery that polar waters are actually warmer at great depths than at the surface—defying the conventional wisdom of the era, which assumed the ocean grew uniformly colder with depth.[4][7]

Today, climatologists are digitizing Scoresby Jr.'s whaling logbooks to reconstruct the Arctic climate of 1810–1825. This period is critical because it coincided with the Dalton Minimum—a period of low solar activity—and the massive 1815 eruption of Mount Tambora, which caused significant global cooling.[2]

Reconstructing historical climates usually relies on proxies like tree rings, ice cores, and coral reefs. However, proxy data can be noisy, and researchers often disagree on the exact magnitude of historical temperature shifts.[2][7]

Direct observational records—like the daily temperature, wind, and ice logs kept by Scoresby—act as a crucial calibration tool for these proxies. Because Scoresby was a scientifically educated observer who used reliable instruments, his logbooks provide a compelling and precise source of information on early 19th-century climate variability.[2]

Projects like ARCdoc at the University of Sunderland have used Scoresby's meticulous definitions of sea ice to map the early 19th-century Arctic ice front. By tracing every sea ice definition in UK maritime history, researchers have been able to build a clearer picture of the Arctic under purely natural weather conditions.[3]

By comparing his logs to modern satellite data, scientists have confirmed that while the 1810s were significantly colder with abundant sea ice, the region still experienced dramatic natural fluctuations. For instance, Scoresby recorded massive clearings of sea ice in the Greenland Sea following the Tambora eruption, highlighting the complex dynamics of the polar climate.[2][3]

Together, the 19th-century Arctic logs of the man and the 20th-century Pacific data of the ship form a vital bridge across time. They allow scientists to separate natural, cyclical climate fluctuations from the unprecedented, human-induced warming we are experiencing today.[3][7]

As the world braces for more frequent and severe El Nino events, the data collected by the William Scoresby is being fed into supercomputers to refine modern predictive models. Understanding exactly how the Humboldt and El Nino currents interacted a century ago helps forecasters predict how they will behave as global temperatures continue to rise.[1][5]

The forgotten voyages of the William Scoresby—and the whaling captain it was named after—demonstrate that the key to predicting our climate future often lies buried in the logbooks of our past. It is a testament to the enduring value of meticulous, curiosity-driven science, proving that observations made a century ago can still save lives today.[1][7]