Last great Pacific cold snap was nearly 1,000 years ago

A new study released in early January says that cooling observed in Pacific deep-ocean temperatures indicates that the deep Pacific is still adjusting to surface cooling that occurred during the Little Ice Age that began nearly 1,000 years ago.

The climate anomaly known as the Little Ice Age brought significantly colder year-round temperature averages to many parts of the globe, and is recognized in paleoclimate and historical records worldwide, said scientists at the Woods Hole Oceanographic Institution in Woods Hole, MA.

Historic climate events such as these impact sea surface temperatures, and due to how the ocean circulates, it’s been theorized that signals related to anomalies like the Little Ice Age are perhaps preserved like memories in the creeping waters of the overturning deep Pacific, according to a summary of the research led by G. “Jake” Gebbie, an associate scientist at the institution with a doctorate in physical oceanography. Whether these signals are predictable or detectable, let alone accurately characterize past surface conditions, remains unclear, according to Gebble and fellow author Peter Huybers.

Their model prediction is largely corroborated by temperature changes identified between measurements taken during the 1870s HMS Challenger expedition and modern temperature observations. The HMS Challenger expedition between 1872 and 1876, led by Professor Charles Wyville Thomson of Edinburgh University, gathered a wide range of data, including ocean temperatures seawater chemistry, current, marine life and the geology of the seafloor.

The results of the Woods Hole study underscore the deep ocean’s role in the planetary heat budget and suggest that the heat loss in the deep Pacific since 1750 offsets nearly a quarter of global heat gain in the upper ocean, the authors said.