HONOLULU (KHON2) -- A recent study on the ancient glaciers of Mauna Kea on Hawaiʻi Island has revealed important insights about how past climate changes affected the region and how these shifts could impact global climate patterns today. The research focused on boulders left behind by glaciers a nd provided evidence about the influence of the Atlantic Meridional Overturning Circulation (AMOC), an ocean current system in the North Atlantic. Here's what scientists discovered: 1. Mauna Kea's ancient glacier Mauna Kea once had a large glacier that was about 70 square kilometers in size. Peter Clark, a professor of geosciences at Oregon State University, explained, “Mauna Kea had a large glacial ice cap of about 70 square kilometers until 14,500 years ago, which has now all disappeared.” This glacier existed during the last ice age and melted as the global climate warmed. 2. A surprising glacier re-growth The research uncovered something unexpected: around 15,400 years ago, Mauna Kea's glacier started to grow again. This growth almost matched the size of the glacier during the ice age. This timing coincided with a slowdown in the AMOC, an ocean current system that helps regulate global climate by moving warm water from the tropics to the North Atlantic. 3. The AMOC and its impact on global climate The AMOC is essential for keeping Europe warmer than expected for its latitude. Studies have shown that when the AMOC slows down, it causes a cooling effect in Europe. But the new research showed that the slowdown of the AMOC didn’t just impact Europe. It also affected places as far away as Hawaiʻi. Clark noted, “The decline of the AMOC basically caused climate changes all over the world.” The study shows that changes in the North Atlantic’s currents can have ripple effects globally. 4. Increased Rainfall and Storm Activity It was found that the glacier’s growth was due to more than colder temperatures; it was also caused by a dramatic increase in rainfall. Scientists found that the amount of rainfall on Mauna Kea during this time was three times greater than it is today. Get Hawaii's latest morning news delivered to your inbox, sign up for News 2 You They believe this increased rainfall may have been caused by more frequent cyclonic storms moving in from the north, further influencing the glacier’s size. 5. Helium isotopes in boulder analysis To pinpoint the timing of the glacier's growth and retreat, the researchers studied boulders left behind by the glacier. By measuring a specific helium isotope in these rocks, they could determine when the boulders were last exposed to the atmosphere. This was a key part of uncovering the history of Mauna Kea’s glacier, as these boulders are the only known record of glaciation in the northern subtropical Pacific. 6. Global climate connections This study supports the idea that changes in the AMOC have a global impact. When the AMOC slows down, it can trigger shifts in climate patterns worldwide. Scientists are concerned that the continued effects of climate change, such as melting ice and changing precipitation patterns, could lead to another slowdown of the AMOC, which could cause significant climate disruptions globally. 7. Mauna Kea’s unique role Mauna Kea is the only place in the northern subtropical Pacific where evidence of ancient glaciation still exists. Although Mauna Loa likely also had glaciers in the past, volcanic eruptions have erased those records. This makes Mauna Kea’s glacier boulders especially important for studying past climate events. You can click here to read the full study. The research shows that changes in the AMOC can have far-reaching consequences for the climate across the planet and can affect regions like Hawaiʻi. Get news on the go with KHON 2GO, KHON's morning podcast, every morning at 8 The study also raises important concerns about future climate changes and the possible slowdown of the AMOC, which could cause significant disruptions to the climate system. ...read more read less