Studies: The race to preserve Earth’s historical climate record—its ice

C&EN discusses the race to preserve Earth’s historical climate record—its ice. As climate change threatens Earth’s glaciers and ice sheets, climatologists and chemists are banking ice core samples for the future.

Ice cores—cylindrical samples drilled from glaciers—have played a central role in helping chart the past climate of Earth and have even helped trace human history and present-day pollution. But climate change puts these precious records at risk: many of the world’s glaciers and ice sheets are melting at an accelerating rate. While chemists continue to develop more sensitive methods to read the chemical messages in the ice, glaciologists are now rushing to study and store ice cores from vulnerable formations. Their goal is to protect this unique source of data about Earth’s natural history for future scientists.

In 1966, they drilled a 1,390 m long ice core and used it to trace Earth’s temperature over the previous 100,000 years (Science 1969, DOI: 10.1126/science.166.3903.377).

The researchers found one part per quadrillion of 239Pu in ice cores from Antarctica and Greenland, deposited there by nuclear testing in the mid-1960s (Environ. Sci. Technol. 2016, DOI: 10.1021/acs.est.6b01108).

Ice core lead levels are therefore a marker of ancient economic activity, war, and plague extending from the Bronze Age to today (Proc. Natl. Acad. Sci. U.S.A. 2018, DOI: 10.1073/pnas.1721818115).

And the loss accelerated by an average of about 5 gigatons per year (Geophys. Res. Lett. 2020, DOI: 10.1029/2019GL086926).

Not only is surface thaw ruining climate records, it’s also affecting people’s water supplies. Researchers have estimated that Quelccaya will stop accumulating ice and begin shrinking in just 30 years (Sci. Rep. 2018, DOI: 10.1038/s41598-018-33698-z).

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