The impact of climate change on meteorite finds in East Antarctica

Antarctica is the most prolific place on Earth to find meteorites, which provide unique insights in the formation and evolution of our Solar System. Over 60% of all meteorite finds on Earth stem from so-called blue ice areas in the interior of the (East) Antarctic ice sheet. In these blue ice areas, a redirected ice flow and meteorological processes lead to the removal of surface layers. Meteorites once embedded in these layers of ice that are removed become exposed at the surface in high concentrations and are easy to spot in the field thanks to their contrasting dark color on blue ice. However, no meteorites have been found in areas where temperatures are relatively high. The absence of meteorites in these areas is explained by the fact that meteorites warm up under solar radiation, and as such these stones can melt the underlying ice, even when surface temperatures are well below zero. This very local melt causes the meteorite to move vertically downward into in the ice sheet, disappearing from the surface and hence impossible to see by eye and collect. Hence, in a warmer climate, meteorites are more prone to become unrecoverable.   Using a data-driven approach, we estimated that with the currently increasing surface temperatures, meteorite loss rates exceed recovery rates multiple times. To estimate this loss rate, we first performed regional climate model simulations, for a low and a high emission scenario, in which blue ice areas are prescribed. Next, we fed this data to a machine learning algorithm that identifies meteorite-rich sites using over 12,000 known meteorite finding locations and their corresponding properties such as ice flow velocity and surface temperature. Until mid-century, projected losses are identical for the emission scenarios, after which losses are reduced for the low emission scenario and nearly constant for the high emission scenario.   These meteorite losses demonstrate a (previously unnoticed) climate sensitivity of the interior of the Antarctic ice sheet. With temperatures remaining well below zero, even with several degrees of warming, meteorites are affected even by very minor (decimal) increases of surface temperatures during exceptionally warm events, which are expected to occur more frequently.