Thread by @ReutersScience

Ice provides historical records about the climate and shows the impact humanity has had. But many glaciers are now melting, prompting renewed urgency among scientists reut.rs/3z8R5Rg 1/8

Scientists are racing to collect ice cores – along with long-frozen records they hold of climate cycles – as global warming melts glaciers and ice sheets.

Some say they are running out of time. And, in some cases, it’s already too late 2/8

Late last year, German-born chemist Margit Schwikowski and a team of international scientists attempted to gather ice cores from the Grand Combin glacier, high on the Swiss-Italian border, for a United Nations-backed climate monitoring effort 3/8

In 2018, they had scouted the site by helicopter and drilled a shallow test core.

The core was in good shape, said Schwikowski: It had well-preserved atmospheric gases and chemical evidence of past climates, and ground-penetrating radar showed a deep glacier 4/8

Not all glaciers in the Alps preserve both summer and winter snowfall; if all went as planned, these cores would have been the oldest to date that did, she said 5/8

But in the two years it took for the scientists to return with a full drilling set-up, some of the information that had been trapped in the ice had vanished 6/8

Freeze-thaw cycles had created icy layers and meltwater pools throughout the glacier, what another team member described as a water-laden sponge, rendering the core useless for basic climate science 7/8

The mission on Grand Combin underscores the major challenge scientists face today in collecting ice cores: some glaciers are disappearing faster than expected.

Read more reut.rs/3z8R5Rg by @CassLGarrison @clarebaldwin and @TmarcoH 8/8