Climate records preserved in Greenlandic ice show that Earth's last ice age included about 25 periods of abrupt climate change, with temperature spikes occurring over decades followed by gradual cooling in the North Atlantic.
Notes on verification
Corroborated by NOAA, Britannica, ScienceDirect, and peer-reviewed literature on Dansgaard-Oeschger events; count of ~25 events is well-established consensus with minor variation across sources. [cascade flags: aggregator_dropped_primary_exists | tier=silver indep_score=1.0 clusters=2 claim_tier=notable]
Sources
- Is the Atlantic Ocean's great conveyer belt really slowing ... (seed:science_and_space)
- https://www.ncei.noaa.gov/sites/default/files/2021-11/2%20Heinrich%20and%20Dansgaard%E2%80%93Oeschger%20Events%20-%20Final-OCT%202021.pdf (corroboration)
- https://www.sciencedirect.com/science/article/pii/S0960982219311169 (corroboration)
- https://www.sciencedirect.com/topics/earth-and-planetary-sciences/dansgaard-oeschger-cycle (corroboration)