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Methane, Monsoons, and Modulation of Millennial‐Scale Climate
- Source :
- Geophysical Research Letters. 47
- Publication Year :
- 2020
- Publisher :
- American Geophysical Union (AGU), 2020.
-
Abstract
- Earths orbital geometry exerts a profound influence on climate by regulating changes in incoming solar radiation. Superimposed on orbitally-paced climate change, Pleistocene records reveal substantial millennial-scale variability characterized by trends, tipping points, and rapid swings. However, the extent to which orbital forcing modulates the amplitude and timing of these millennial variations is unclear. Here we isolate the magnitude of millennial-scale variability (MMV) in two well-dated records, both linked to precession cycles (19,000-23,000-year periodicity): atmospheric methane and Chinese speleothem δ¹⁸O, where the latter is commonly interpreted as a proxy for Asian monsoon intensity. At the millennial timescale (1,000-10,000 years), we find a fundamental decoupling wherein precession directly modulates the MMV of methane but not that of speleothem-δ¹⁸O. We hypothesize that mid-to-high latitude insolation modulates the MMV of atmospheric methane, but feedbacks internal to the Earth-climate system modulate the strength of millennial-scale monsoonal circulation.
- Subjects :
- geography
geography.geographical_feature_category
010504 meteorology & atmospheric sciences
Orbital forcing
Atmospheric methane
Speleothem
Climate change
010502 geochemistry & geophysics
Monsoon
01 natural sciences
Methane
Latitude
chemistry.chemical_compound
Geophysics
chemistry
Climatology
General Earth and Planetary Sciences
Environmental science
East Asian Monsoon
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 19448007 and 00948276
- Volume :
- 47
- Database :
- OpenAIRE
- Journal :
- Geophysical Research Letters
- Accession number :
- edsair.doi...........56dbeef8dd0f8694149a4c95e97f2e91