Glacial cycles triggered by burial carbon release

Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion EGU Abstract A new mechanism is proposed in which climate, carbon cycle and icesheets interact with each other to produce a feedback that can produce quasi-100 ky glacial-interglacial cycles. A key process is the burial and preservation of organic carbon by icesheets. The switch from glacial maximum to deglaciation is triggered by the ejection 5 of glacial burial carbon when icesheets grow to sufficiently large size and subglacial transport becomes significant. Glacial inception is initiated by CO 2 drawdown due to a " rebound " from a high but transient interglacial CO 2 value as the land-originated CO 2 invades into deep ocean via thermohaline circulation and CaCO 3 compensation. Also important for glacial inception is the CO 2 uptake by vegetation regrowth in the 10 previously ice-covered boreal regions. When tested using a fully coupled Earth system model with comprehensive carbon cycle components and semi-empirical physical climate components, it produced self-sustaining glacial-interglacial cycles of duration about 93 ky, CO 2 change of 90 ppmv, temperature change of 6 • C under certain parameter regimes. Since the 100 ky cycles can not be easily explained by the weak 15 Milankovitch astronomical forcing alone, this carbon-climate mechanism provides a strong feedback that could interact with external forcings to produce the major observed Quaternary climatic variations.