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SUMMARY:Earth’s energy imbalance and ocean heat content on orbital to mi
 llennial timescales reconstructed from noble-gas ratios in ice cores - Mar
 kus Grimmer\, University of Bern
DTSTART:20260204T173000Z
DTEND:20260204T190000Z
UID:TALK242953@talks.cam.ac.uk
CONTACT:Emily Kraus
DESCRIPTION:Earth’s energy imbalance (EEI) determines whether the planet
  experiences a net gain or loss of energy. The ongoing rise in atmospheric
  greenhouse-gas concentrations causes a positive EEI\, which ultimately dr
 ives global warming. Today\, most of this excess heat is taken up by the s
 urface ocean. On millennial to orbital timescales\, by contrast\, energy p
 artitions between two considerably larger but slower-responding reservoirs
 : the global (deep\, intermediate\, and surface) ocean and the latent heat
  involved in waxing and waning land ice. Ocean heat content (OHC) and glob
 al sea level\, which mirrors land ice volume\, are therefore key metrics t
 o assess the global energy balance during the Quaternary.\n\nPast OHC can 
 be reconstructed by analyzing noble-gas ratios in polar ice cores. This me
 thod relies on two properties of noble gases: firstly\, noble gases have t
 emperature-dependent and species-specific solubility in seawater\; and sec
 ondly\, noble gases are chemically inert\, such that their total inventory
  is conserved in the coupled ocean–atmosphere system. Ice cores contain 
 ancient air\, from which past atmospheric noble-gas ratios can be reconstr
 ucted. Using the above-mentioned properties of noble gases\, past mean oce
 an temperature and OHC can then be derived from these atmospheric noble-ga
 s ratios. \n\nHere\, I present a new OHC dataset\, which spans over an ent
 ire glacial cycle (MIS 9–7) and covers the last four glacial termination
 s in millennial resolution\, substantially extending the existing OHC reco
 rd. By combining this new OHC record with past sea-level reconstructions\,
  we obtain an EEI record across an entire glacial cycle. This EEI record n
 ot only features orbital-scale variability in response to the albedo and g
 reenhouse-gas forcing but also exhibits strong millennial power. These mil
 lennial-scale EEI changes\, which are mirrored in OHC\, have consequences 
 for the interpretation of past sea-level\, atmospheric CO2\, and climate.\
 n
LOCATION:Latimer Room\, Clare College
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