Antarctic meteorites threatened by climate warming

Abstract

More than 60% of meteorite finds on Earth originate from Antarctica. Using a data-driven analysis that identifies meteorite-rich sites in Antarctica, we show climate warming causes many extraterrestrial rocks to be lost from the surface by melting into the ice sheet. At present, approximately 5,000 meteorites become inaccessible per year (versus ~1,000 finds per year) and, independent of the emissions scenario, ~24% will be lost by 2050, potentially rising to ∼76% by 2100 under a high-emissions scenario.

Keywords: Climate-change impacts; Cryospheric science.

Fig. 1. Antarctic meteorites in blue ice areas.

a, Schematic representation of the meteorite concentration mechanism, with a supply of meteorites through ice flow and direct infall and loss of meteorites through melting from the surface into the ice (sinking, red arrows). The sinking of meteorites is caused by (increased) warming of the dark meteorites (especially those with high metal contents and thermal conductivity) under solar radiation, causing the underlying ice to melt, and hence the meteorite to sink into the ice. b, The Hutchison Icefield 18033 meteorite (49 g) collected as part of the Lost Meteorites of Antarctica Project^,. c, Meteorite MIL 07710 (147 g) fully enclosed in ice, collected as part of the Antarctic Search for Meteorites (ANSMET) programme (the number in the photo is used for documentation in the field). A column of clear, bubble-free ice above the meteorite was observed during the field mission (transparent on photograph), indicating that the meteorite sunk through melting underlying ice that refroze as superimposed ice above the sample. Credit: b, Katherine Joy, Lost Meteorites of Antarctica Project^,; c, Ralph Harvey, ANSMET programme.

Fig. 2. Projected evolution of meteorites in Antarctica under climate warming.

a, Antarctic meteorite finds up to 2020 (that is, including January or February 2019, not including 2020) documented in the Meteoritical Bulletin (averaged over 5 yr intervals) and predicted future loss rates (averaged over 20 yr intervals) for a low-emissions scenario (Shared Socio-economic Pathway (SSP)1-2.6) and a high-emissions scenario (SSP5-8.5) (Supplementary Fig. 1). Estimates for the two emissions scenarios start to deviate from 2052; therefore loss rates for 2020–2040 are averaged for the two scenarios with the error bar representing the lower and upper estimates. b, The projected number of meteorites remaining at the ice sheet surface in relation to global air temperature increase with respect to pre-industrial levels (1850–1900; Supplementary Fig. 3). The graph displays the average estimate (bold line) and both the lower and upper bounds (grey shading; Methods), and indicates under which temperature increase 25%, 50% and 75% of the meteorites are lost. c, Continent-wide estimate of meteorite stranding zones (MSZs) in 2020 and in 2100 under SSP5-8.5 (both exaggerated with buffers of 10 km for visual clarity). The pie charts show the number of meteorites lost under global air temperature increases relative to pre-industrial values (colour scale) for the regions outlined in grey. In other parts of the Antarctic continent^, (that is, in regions that are not within grey boundaries), the total estimated numbers of meteorites are negligible (~0.5% of all meteorites in 2020). d, Unexplored meteorite stranding zones in the Petermann ranges in 2020 (pink) and 2100 (under SSP5-8.5, red). Potential new areas that appear are mostly snow covered (Methods). Background data are false-colour Landsat satellite images. e, Identified meteorite stranding zones in the Allan Hills and Elephant Moraine area. The Allan Hills meteorite stranding zone (~1,800 meteorite finds so far) is projected to persist under a warming climate, while those at Elephant Moraine (~2,500 meteorite finds so far) and Reckling Moraine (~150 meteorite finds so far) are projected to disappear before 2100 under SSP5-8.5. Credit: d,e, Landsat Image Mosaic of Antarctica (LIMA) project.