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Ancient Sea Temperature Revealed from Snowball Earth Era

3/1/2026

Summary

Story summary

Researchers reported first measured sea temperature from a snowball Earth episode as –15°C ± 7°C.
The event occurred 717 million years ago, when Earth froze and seas were anoxic.
Seawater was up to four times saltier than today, preventing freezing.
Geochemist Andy Heard said the temperature estimate should be interpreted qualitatively.
Jochen Brocks' analysis of Australian sediments supports the findings and suggests the brine could have reached –7°C before freezing.

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Story summary

Researchers reported first measured sea temperature from a snowball Earth episode as –15°C ± 7°C.
The event occurred 717 million years ago, when Earth froze and seas were anoxic.
Seawater was up to four times saltier than today, preventing freezing.
Geochemist Andy Heard said the temperature estimate should be interpreted qualitatively.
Jochen Brocks' analysis of Australian sediments supports the findings and suggests the brine could have reached –7°C before freezing.