Ice Free World??Ice Free World??

Presented by:Presented by:

Akindele Balogun.Akindele Balogun.

• The Earth is warmer today than it The Earth is warmer today than it has been in many millennia.has been in many millennia.

Questions:Questions:

1.1. How warm has the earth been in How warm has the earth been in the past?the past?

2.2. What caused the warming?What caused the warming?

3.3. How would the world be different if How would the world be different if this was the case?this was the case?

Was it always this way??Was it always this way??

Or maybe like this……..Or maybe like this……..

Weathering IndexWeathering Index

LPTM/PETM(~55mya)LPTM/PETM(~55mya)

• Paleocene- Eocene Thermal Paleocene- Eocene Thermal Maximum (also referred to as Late Maximum (also referred to as Late Paleocene Thermal Maximum). Paleocene Thermal Maximum).

• Onset of both the thermal maximum Onset of both the thermal maximum and the Carbon Isotope Excursion and the Carbon Isotope Excursion (CIE)(CIE)

• Short-term biotic and Short-term biotic and paleoenvironmental changes paleoenvironmental changes

LPTM LPTM vs. vs. PETM?PETM?• Late Late

Paleocene Paleocene Thermal Thermal MaximumMaximum

• Paleocene-Paleocene-Eocene Eocene Thermal Thermal MaximumMaximum

LPTM LPTM vs. vs. PETM?PETM?• Late Late

Paleocene Paleocene Thermal Thermal MaximumMaximum

• Paleocene-Paleocene-Eocene Eocene Thermal Thermal MaximumMaximum

Cause of warming (Greenhouse Cause of warming (Greenhouse Effect)Effect)

• Release of CORelease of CO22, CH, CH44 and H and H22O into the O into the atmosphere.atmosphere.

• Dissociation of methane hydratesDissociation of methane hydrates

-Volcanism-Volcanism

- Comet Impact- Comet Impact

• Failure of Carbon reservoir i.e. Failure of Carbon reservoir i.e. continental slopescontinental slopes

Evidence in Support of Ice Free Evidence in Support of Ice Free World.World.

• Warm-adapted vegetation (preserved Warm-adapted vegetation (preserved at poles)at poles)

• Global Sea level riseGlobal Sea level rise

• Isotope data (Oxygen and Carbon)Isotope data (Oxygen and Carbon)

High resolution records of the LPTM High resolution records of the LPTM and circum-Caribbean volcanism: is and circum-Caribbean volcanism: is there a casual link?there a casual link? Brawler Brawler et. al.et. al. (1997) (1997)• Rapid and changes in stable carbon isotope Rapid and changes in stable carbon isotope

is due to volcanismis due to volcanism• Volcanic activity in the Caribbean warmed Volcanic activity in the Caribbean warmed

high latitude waters – causing deep water high latitude waters – causing deep water supply from low latitude. supply from low latitude.

• Dissociation of Methane hydites from Dissociation of Methane hydites from warming deep waters. warming deep waters.

• Problem- Climate model and observed Problem- Climate model and observed tropical warming in the LPTM are at odds tropical warming in the LPTM are at odds with volcanic COwith volcanic CO22 induced warming induced warming Mechanism.Mechanism.

Case for tropical warmingCase for tropical warming• δδ1313C excursion at PETM coincides with C excursion at PETM coincides with

small but significant decrease in small but significant decrease in δδ1818O - O - Indicating rise in SST.Indicating rise in SST.

• Diminished CaCODiminished CaCO33 at sites reflect shoaling at sites reflect shoaling of lysocline and CCD – CaCOof lysocline and CCD – CaCO3 3 dissolution is dissolution is consistent with addition of massive consistent with addition of massive amounts of carbon from the oxidized amounts of carbon from the oxidized methane hydrates (Acidic Condition)methane hydrates (Acidic Condition)

• Lack of evidence of observed tropical Lack of evidence of observed tropical warming is attributed to circum-Caribbean warming is attributed to circum-Caribbean eruptions – Stratospheric sulfate aerosols eruptions – Stratospheric sulfate aerosols (e.g. Pinatubo (1991).(e.g. Pinatubo (1991).

• Tephra (volcaniclasts) layers are more Tephra (volcaniclasts) layers are more abundant in the PETM indicating lots of abundant in the PETM indicating lots of volcanic activity. volcanic activity.

Bralower et al. LPTM paperBralower 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 Carbon cycling and chronology of climate warming during the Paleocene/Eocene warming during the Paleocene/Eocene transition.transition.Norris and Rohl(1999)Norris and Rohl(1999)• Suggests that large shifts in Suggests that large shifts in δδ1313CC at the PETM is due at the PETM is due

to dissociation of Methane hydrates – injection of to dissociation of Methane hydrates – injection of 1,200-2000 gtons of Carbon into Ocean & 1,200-2000 gtons of Carbon into Ocean & atmosphereatmosphere

• Used magnetochronology to establish that timing of Used magnetochronology to establish that timing of –ive CIE coincides with extinction of benthic forams –ive CIE coincides with extinction of benthic forams

• Methane or another source supplied carbon into the Methane or another source supplied carbon into the atmosphere & oceans faster than it could be atmosphere & oceans faster than it could be removed by burial.removed by burial.

• Residence time of Carbon=120kyrs – similar to Residence time of Carbon=120kyrs – similar to modeled response after massive input of methane modeled response after massive input of methane

• CO2 induced greenhouse warming due to collapse of CO2 induced greenhouse warming due to collapse of hydrate reservoir and slope failure under warm hydrate reservoir and slope failure under warm water. water.

Peaks of maximum intensity rep 23k and 19k cycles

A case for comet impact trigger for the A case for comet impact trigger for the Paleocene/Eocene thermal maximum Paleocene/Eocene thermal maximum and carbon isotope excursionand carbon isotope excursion Kent Kent et. al.et. al. (2003) (2003)

• Hypothesize rapid CIE and dissociation Hypothesize rapid CIE and dissociation of sea floor methane hydrate is as a of sea floor methane hydrate is as a result of comet impact result of comet impact

Evidence Evidence

• Indirect evidence of impact- abundance of Indirect evidence of impact- abundance of magnetic nanoparticles in Kaolinite rich magnetic nanoparticles in Kaolinite rich shelf sedimentsshelf sediments

• Sudden increase in kaolinite is thought to Sudden increase in kaolinite is thought to represent the redeposition on the marine represent the redeposition on the marine shelf of rapidly weathered impact ejectashelf of rapidly weathered impact ejecta

• Supporting evidence - Iridium anomaly at Supporting evidence - Iridium anomaly at Paleocene/Eocene boundaryPaleocene/Eocene boundary

• Anomalously high magnetized sediment Anomalously high magnetized sediment were found at CIE were found at CIE

Interplanetary Dust ParticlesInterplanetary Dust Particles