Disparate energy sources for slow and fast Dansgaard-Oeschger cycles
During the Late Pleistocene, Dansgaard-Oeschger (DO) cycles triggered warming events that were as abrupt as the present-day human-induced warming. However, in absence of a periodic forcing operating on millennial time scales, the main energy sources of DO cycles remain debated. Here, we identify the...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/cp-2023-6 https://cp.copernicus.org/preprints/cp-2023-6/ |
| Summary: | During the Late Pleistocene, Dansgaard-Oeschger (DO) cycles triggered warming events that were as abrupt as the present-day human-induced warming. However, in absence of a periodic forcing operating on millennial time scales, the main energy sources of DO cycles remain debated. Here, we identify the energy sources of DO cycles by applying a bispectral analysis to the North Greenland ice core project (NGRIP) oxygen isotope (δ 18 O ice ) record—a 123-thousand-years (kyr) long proxy-record of air-temperatures (T air ) over Greenland. For both modes of DO cyclicity—slow and fast—we detect disparate energy sources. Slow-DO cycles are marked by multi-millennial periodicities in the 12.5 to 2.5 kyr bandwidth and receive energy from astronomical periodicities. Fast-DO cycles have millennial periodicities in the 1.5 ± 0.5 kyr range and receive energy from centennial periodicities. We propose cryospheric and oceanic mechanisms that facilitate the transfer of energy from known sources to slow- and fast-DO cycles, respectively. Our findings stress the importance of understanding energy-transfer mechanisms across a broad range of time scales to explain the origins of climate cycles without primary periodic energy-sources. |
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