Presented by: Akindele Balogun. Ice Free World?? Presented by: Akindele Balogun.

The Earth is warmer today than it has been in many millennia. Questions: How warm has the earth been in the past? What caused the warming? How would the world be different if this was the case?

Was it always this way??

Or maybe like this……..

Weathering Index

LPTM/PETM(~55mya) Paleocene- Eocene Thermal Maximum (also referred to as Late Paleocene Thermal Maximum). Onset of both the thermal maximum and the Carbon Isotope Excursion (CIE) Short-term biotic and paleoenvironmental changes

LPTM vs. PETM? Late Paleocene Thermal Maximum Paleocene-Eocene Thermal Maximum

LPTM vs. PETM? Late Paleocene Thermal Maximum Paleocene-Eocene Thermal Maximum

Cause of warming (Greenhouse Effect) Release of CO2, CH4 and H2O into the atmosphere. Dissociation of methane hydrates -Volcanism - Comet Impact Failure of Carbon reservoir i.e. continental slopes

Evidence in Support of Ice Free World. Warm-adapted vegetation (preserved at poles) Global Sea level rise Isotope data (Oxygen and Carbon)

High resolution records of the LPTM and circum-Caribbean volcanism: is there a casual link? Brawler et. al. (1997) Rapid and changes in stable carbon isotope is due to volcanism Volcanic activity in the Caribbean warmed high latitude waters – causing deep water supply from low latitude. Dissociation of Methane hydites from warming deep waters. Problem- Climate model and observed tropical warming in the LPTM are at odds with volcanic CO2 induced warming Mechanism.

Case for tropical warming δ13C excursion at PETM coincides with small but significant decrease in δ18O - Indicating rise in SST. Diminished CaCO3 at sites reflect shoaling of lysocline and CCD – CaCO3 dissolution is consistent with addition of massive amounts of carbon from the oxidized methane hydrates (Acidic Condition) Lack of evidence of observed tropical warming is attributed to circum-Caribbean eruptions – Stratospheric sulfate aerosols (e.g. Pinatubo (1991). Tephra (volcaniclasts) layers are more abundant in the PETM indicating lots of volcanic activity.

Bralower et al. LPTM paper

Benthic foraminifera extinction in the PETM, carbonate shift due to carbon isotope depletion during claystone diagenesis; formation of sulphides

Frequency of Tephra layers

Carbon cycling and chronology of climate warming during the Paleocene/Eocene transition. Norris and Rohl(1999) Suggests that large shifts in δ13C at the PETM is due to dissociation of Methane hydrates – injection of 1,200-2000 gtons of Carbon into Ocean & atmosphere Used magnetochronology to establish that timing of –ive CIE coincides with extinction of benthic forams Methane or another source supplied carbon into the atmosphere & oceans faster than it could be removed by burial. Residence time of Carbon=120kyrs – similar to modeled response after massive input of methane CO2 induced greenhouse warming due to collapse of hydrate reservoir and slope failure under warm water.

Peaks of maximum intensity rep 23k and 19k cycles

A case for comet impact trigger for the Paleocene/Eocene thermal maximum and carbon isotope excursion Kent et. al. (2003) Hypothesize rapid CIE and dissociation of sea floor methane hydrate is as a result of comet impact

Evidence Indirect evidence of impact- abundance of magnetic nanoparticles in Kaolinite rich shelf sediments Sudden increase in kaolinite is thought to represent the redeposition on the marine shelf of rapidly weathered impact ejecta Supporting evidence - Iridium anomaly at Paleocene/Eocene boundary Anomalously high magnetized sediment were found at CIE

Interplanetary Dust Particles