Abrupt climate change occurred naturally many times during the last ice age (the last glacial period, roughly 115,000 to 11,700 years ago).

Paleoclimate records, especially from Greenland ice cores, document at least 25 major rapid warming-cooling oscillations known as Dansgaard-Oeschger (D-O) events.

The query refers to Klimaschau (Climate Show) Episode 256 from EIKE (Europäisches Institut für Klima und Energie).

The ~5.5-minute video, uploaded April 12, 2026, is titled “Abrupter Klimawandel – menschgemacht oder natürlich?” (English auto-dub: “Abrupt climate change – man-made or natural?”). It directly challenges the narrative that current warming is “unprecedentedly rapid” due to industrial CO₂ emissions since 1850, highlighting instead that scientists have long documented rapid natural climate shifts.

Episode 256 correctly shows that abrupt climate change occurred naturally many times (D-O events prove it).

This is mainstream paleoclimate science and underscores the climate system’s non-linear sensitivity.

The episode’s core point: abrupt climate shifts are natural, globally interconnected, and have happened repeatedly under glacial conditions — so today’s changes are not uniquely “man-made” in character or speed.

The 2017 Nature Geoscience paper:”Global atmospheric teleconnections during Dansgaard–Oeschger events” by Bradley R. Markle and co-authors (including Eric J. Steig, Christo Buizert, and others). It was published in January 2017 (Volume 10, pages 36–40).

This study provides key evidence for atmospheric (in addition to oceanic) linkages during the ~25 Dansgaard-Oeschger (D-O) events of the last ice age.

Using high-resolution ice-core records and climate modeling, the authors demonstrate that abrupt warmings in Greenland were accompanied by rapid, global-scale atmospheric teleconnections that affected distant regions within decades.

The study used high-resolution deuterium-excess records from the West Antarctic Ice Sheet Divide (WDC) ice core to track changes in the latitude of moisture sources for Antarctic snow — a proxy that responds quickly to atmospheric shifts.

This is exactly the paper referenced in the Klimaschau Episode 256 (and many skeptical discussions) when highlighting that D-O events had global reach through fast atmospheric pathways — all occurring naturally under glacial conditions with low CO₂ (~180–220 ppm) and no human influence.

In short, the statement is factually correct: abrupt, large-magnitude climate shifts happened repeatedly and naturally ~25 times during the last ice age, driven by ocean/ice dynamics.

This underscores climate variability and the importance of understanding feedbacks, but it does not negate the distinct mechanisms and boundary conditions of current changes.

Dansgaard-Oeschger (D-O) events are one of the most striking examples of abrupt climate change in Earth’s recent geological history. They were rapid, large-scale temperature oscillations that occurred repeatedly during the last glacial period (approximately 115,000 to 11,700 years ago).

Named after Danish glaciologist Willi Dansgaard and Swiss geophysicist Hans Oeschger, who identified them in the 1970s–1980s from Greenland ice cores, these events show a distinctive “saw-tooth” pattern in temperature proxy records:

Abrupt warming: Temperatures over Greenland jumped by 8–16°C (14–29°F) — sometimes up to ~16.5°C — in just a few decades (often 30–50 years). This shifted the climate from full glacial “stadial” cold to milder “interstadial” conditions.

Gradual cooling: Temperatures then declined slowly over centuries to more than 1,000 years, returning to cold stadial conditions.

Scientists have identified approximately 25 such events. They were most frequent and pronounced between ~80,000 and 20,000 years ago, recurring irregularly on millennial timescales (average ~1,000–2,000 years, with some evidence of a ~1,470-year pacing).

The graph above (from NGRIP ice core data) clearly shows the numbered D-O events as sharp upward spikes (warmings) followed by slower declines.

Evidence from Ice Cores and Beyond:

Primary data: High-resolution oxygen isotope ratios (δ¹⁸O) in Greenland ice cores (GISP2, GRIP, NGRIP). Higher δ¹⁸O = warmer air temperatures. Other proxies include lower dust content and nitrogen isotopes during warm phases.

Global and hemispheric signals: The events appear in marine sediments, lake cores, speleothems (cave deposits), and even pollen records worldwide. A 2026 study (Liu et al. in Climate of the Past) used global pollen databases to reconstruct land climate changes during D-O events, confirming widespread terrestrial impacts.

Bipolar seesaw: Antarctic ice cores (e.g., Vostok, EPICA Dome C) show an opposite pattern — when Greenland warmed abruptly, Antarctica often cooled slightly (and vice versa). This is due to rapid redistribution of heat via changes in ocean circulation.

The top panel here compares Antarctic (red/yellow) and Greenland (blue/purple) isotope records over 140,000 years, highlighting the anti-phased behavior.

Related Heinrich events (~6 major ones) involved massive iceberg discharges into the North Atlantic, often coinciding with the coldest phases between D-O cycles.

D-O events were driven by internal variability in the climate system under glacial boundary conditions (huge Northern Hemisphere ice sheets, low sea levels, different orbital forcing via Milankovitch cycles, and low CO₂ levels of ~180–220 ppm):

Main mechanism: Instability in the Atlantic Meridional Overturning Circulation (AMOC) — the ocean’s “conveyor belt.” Freshwater pulses (from melting ice or precipitation) weakened it, cooling the North Atlantic. Recovery of the AMOC then triggered rapid warming.

Amplifiers: Sea-ice expansion/contraction in the North Atlantic and atmospheric circulation shifts.

No large external forcing (like today’s CO₂ spike) was needed — modest CH₄ rises often lagged the Greenland warming, while CO₂ changes aligned more with Antarctic signals.

D-O events prove that Earth’s climate can shift dramatically and rapidly due to natural internal dynamics, even without strong external forcings.

In short, Dansgaard-Oeschger events are a textbook case of natural abrupt climate variability — dramatic, well-documented, and a reminder of the climate system’s non-linear behavior.

Ongoing research (including 2026 global pollen reconstructions) continues to refine our picture of their worldwide effects.