Hawai‘i’s Last Permafrost

Maunakea on the Big Island. Photo courtesy of UH

In the coldest climate, on the tallest summits of Hawaiʻi, temperatures fall below freezing during winter nights. In 1969, Alfred Woodcock discovered areas inside cinder cones on Maunakea that are permanently frozen. At one place the ice was about 32 feet thick and 27 yard long, buried beneath about one foot of boulders, the only permanent ice known in all of the Hawaiian Islands, as recently reported by UH.

Recently, a group of scientists, and their students investigated the state and health of this unique permafrost, in a way that involves minimal disturbance to the environment. Because these ice-rich bodies lie buried beneath the surface, they are not easy to locate. After extensive temperature measurements and targeted geophysical surveys sponsored by the Office of Maunakea Management, the permafrost has been re-documented.

Some of the ice found by Woodcock inside Puʻuwēkiu Crater is still there, but most of it has disappeared. Its north-south extent, once 27 yards, is now 12 yards; its thickness, once 32 feet, is now 12 feet. The ice has retreated all around. If the trend between 1973 and 2015 is extrapolated, the remainder may disappear within a few years.

The results of the permafrost survey were published in the journal Permafrost and Periglacial Processes.

Read more about the permafrost survey at the Office of Maunakea Management website.