According to a new study, the retreat of glaciers in some major regions may have commenced as early as the 1940s, or possibly even sooner.

Glacier Melting Began Earlier Than Previously Thought

A research team led by the University of Houston collected sedimentary rock cores from seven locations near the massive Thwaites Glacier and the neighboring Pine Island Glacier to accurately determine when the current melting began to accelerate.

These rock samples, dating back more than 10,000 years, tell the history of the ice sheets from a time before satellites could observe them, thus helping to confirm estimations about the history of Thwaites Glacier's retreat.

The massive ice river, with a diameter of about 120 kilometers, is one of the Earth's largest glaciers. It is sometimes referred to as the "Doomsday Glacier" because its demise would signify a significant and irreversible change in Antarctica.

Measurements based on the characteristics of the ice cores collected near the two glaciers matched well enough for the researchers to conclude that they are observing the effects of considerable changes in the Antarctic environment.

"Our study is particularly important because the change is not random and is not limited to one glacier," said Rachel Clark, a geologist at the University of Houston, to the online scientific portal ScienceAlert. "This shift is part of broader climate changes; one simply cannot ignore what is happening on this glacier."

Clark added that, combined with previous models, the results point towards an extreme El Niño weather pattern that warmed the waters of Western Antarctica between 1939 and 1942, likely preceding significant ice sheet retreat.

Significant Retreat Observed

Experts believe that these external factors (rather than internal ice dynamics) were sufficient to allow more of the ice to float freely instead of remaining anchored to the sea floor. The retreat of this grounding zone contributes to greater instability and melting as more of the ice base comes in contact with warming waters.

The study, published in the journal PNAS, indicates that once an ice sheet begins to shrink, melting can continue for decades, even if the initial triggers are no longer present. This is an important consideration for scientists studying ice melt.

"It is significant that the El Niño lasted only a few years, but the Thwaites and Pine Island glaciers continue to exhibit significant retreat to this day," explained Julia Wellner, geologist and colleague at the University of Houston. "Once the system is knocked out of balance, the retreat becomes continuous."

According to data, the Thwaites Glacier has lost more than 1,000 billion tons of ice since the turn of the century. Scientists believe that a better understanding of what triggered the increased melting in the past could help model the extent of future problems. If Thwaites becomes destabilized, there is a potential for all of Western Antarctica's ice to become unstable.