Paleoclimate
MPT may lag a stronger ice-age feedback
Open access · cc by · source: Europe PMC
A carbon-cycle oscillator locks ice-age periods to 40, 80, then 120 kyr as feedback grows, and the period jump can lag the parameter change by up to ~10 Myr.
Study at a glance
- Design
- Computational / modelling — Calcifier-alkalinity carbon-cycle oscillator with growing weathering feedback under obliquity
- N
- Idealized dynamical-system experiments; not an observational sample N
- Population
- Modeled glacial–interglacial carbon-cycle oscillator under 40-kyr forcing
- Outcome
- Period locking to 40/80/120 kyr with delayed response after feedback strengthening
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Unforced oscillations last 14 kyr until a Hopf bifurcation; stronger feedback stretches the free period toward 120 kyr near γ≈0.12. With forcing, duration locks at 40, 80, and 120 kyr, but after an abrupt feedback jump the period can take ~1–10 Myr to move to the next multiple.
Methodology
Authors added a bounded positive weathering feedback to the calcifier-alkalinity model, forced it with 40-kyr obliquity, and jumped the feedback strength to watch how locked cycle length responded.
Limitations
The 2-equation alkalinity toy model is not a GCM; the instantaneous γ jump is admitted to be unrealistic; this paper does not fit new paleo time series, so the delay is a mechanism, not a dated MPT cause.
How this study connects
Role on claims
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Evidence for the claim as stated.
A carbon-cycle oscillator locks ice-age periods to 40, 80, then 120 kyr as feedback grows, and the period jump can lag the parameter change by up to ~10 Myr.
Evidence for the claim as stated.
A local speleothem or tree-ring drought record is not a global temperature curve.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
A local speleothem or tree-ring drought record is not a global temperature curve.
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