Each meteorite tells a unique tale about the solar system and how it was formed. But the climate crisis threatens this trove of scientific information, according to a new study.
The icy plains of Antarctica are a magnet for meteorite hunters like Maria Valdes, a research scientist at the Field Museum of Natural History and the University of Chicago. Approximately 1,000 space rocks are found in the region each year. Their dark hue is easy to spot in the white expanse.
“Antarctica, a desert of ice, provides an ideal background for meteorite recovery — go to the right place, and any rock you find must have fallen from the sky,” said Valdes, who visited the region as part of an expedition team in late 2022 and early 2023 for her work at the museum’s Robert A. Pritzker Center for Meteoritics and Polar Studies. The international team found five meteorites.
“We stumbled across an enormous brown stone sitting by itself in the middle of an ice field. It was a little bit smaller than a bowling ball and quite heavy — 7.6 kg (about 17 pounds),” she said via email. “I had seen and handled so many meteorites in my career, but finding one yourself is such a different feeling.”
Formed from extraterrestrial bodies such as the moon, Mars, or large asteroids, each meteorite tells a unique tale about the solar system and its formation. But the climate crisis threatens this trove of scientific information. Meteorites are disappearing into the ice, putting them out of the reach of scientists.
“As the climate continues to warm, Antarctic rocks are sinking into the ice at an increasing rate. Over time, this will make many meteorites inaccessible to scientists,” said Valdes, who wasn’t involved in the latest research. “We lose precious time capsules that hold clues to the history of our solar system.”
As Earth warms, about 5,000 meteorites could disappear from the surface of melting ice sheets every year, according to the study published Monday in the journal Nature Climate Change. To date, more than 48,000 meteorites have been discovered in Antarctica, accounting for about 60% of specimens found globally.
How to Find a Meteorite
Meteorites, lumps of rock that fall from space through Earth’s atmosphere, do not fall in an evenly scattered pattern across the frozen continent. Concentrations emerge in certain locations because of geography and weather patterns, Valdes explained.
Meteorites are particularly plentiful in blue ice fields. In these areas, a combination of ice flow processes and local weather conditions remove layers of snow and ice from the surface, exposing meteorites that were once embedded in the ice. The windblown ice tends to look blue compared with the surrounding surface snow.
“Over significant stretches of time (tens or hundreds of thousands of years) phenomenal concentrations of meteorites can develop, as high as one per square meter in some locations,” she said.
Researchers have identified areas of meteorite-rich blue ice mostly by luck. However, to systematize the search, Veronica Tollenaar, a doctoral researcher at Université Libre de Bruxelles in Belgium, and her colleagues used a machine-learning algorithm to create a “treasure map” of probable meteorite-rich zones, based on factors including surface temperature, surface slope, surface cover, and ice flow movement.
That research, published in January 2022 in the journal Science Advances, identified 600 zones and suggested that 300,000 meteorites are still present at the surface of the ice sheet. Valdes said in 2023 she and her colleagues used the information to help inform their decision on exactly where to search during their expedition.
“Our experience indicates that so far, Tollenaar’s approach only works to a first order. Local parameters such as topography and wind directions that can redistribute meteorites from blue ice fields into local meteorite traps have to be considered as well,” Valdes said.
In the new study, co-lead author Tollenaar and her team projected the loss of meteorites under different climate change scenarios by combining climate modeling with their work from the 2022 paper.
Meteorites can sink into the ice even if temperatures are below zero degrees Celsius (32 Fahrenheit). The sun heats up the dark rock, which absorbs solar radiation more easily because of its color, which melts the surrounding ice. “With that heat, it can locally melt the ice and slowly disappear from the surface,” Tollenaar said.
The threat to these celestial archives underscores the broader implications of climate change, emphasizing the need for immediate and sustained action to mitigate its impact on our planet and its natural records.
