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Ice Cores and Earth’s Ancient Atmosphere�Signals of past CO2 changes�

The U.S. National Science Foundation,

office of Polar Programs

Oregon State University

Jon Edwards

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Outline

  • Introduction- Our climate system
  • Objectives

-Ice cores and atmospheric gases

-A lead or a lag- what does it mean

-Tipping our planet out of an ice age – Milankovitch Cycles

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Ruddiman (2007)

  • The primary energy to our planet is the sun
  • The solar energy that reaches Earth’s surface depends on latitudinal, position on the planet, internal solar processes, changes in Earth's orbit
  • Our climate system is defined by a complex series of interactions and feedbacks
  • An external change in any one component will affect the rest

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https://sustainability.illinois.edu/charles-david-keeling-1928-2005/

Since the mid-1950s remarkably accurate records of CO2 have been made from air monitoring stations around the world.

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The question arises- what happened before 1950?

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Bubble trapping in the ice core

Firn is the intermediate stage between snow and ice

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The top 50-120 m of the ice sheet is the porous firn column

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Gas bubbles are locked-in near the base of the firn (firn-ice transition)

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  • Atmospheric gases become trapped in ice through firn processes.
  • The porous structure of the firn allows to move between the surface and the lock in zone.
  • In the lock in zone, the air is of the same age as the surface
  • The difference in the age of the ice and the air that becomes trapped is referred to as delta age

Lock in zone

Ice cores and atmospheric gases

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Atmosphere

Ice cores and atmospheric gases

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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Atmosphere

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iceandclimate.nbi.ku.dk

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  • Continuous ice core records extend back 800 000 years.
  • Over the past 800 000 years, prior to the industrial revolution, there have been 8 glacial-interglacial cycles.
  • Greenhouse gases and temperature have followed each other with a periodicity corresponding to variations in Earth’s orbit.
  • CO2 ranges between 180ppm to 300ppm and CH4 ranges between 350ppb to 800ppb over glacial interglacial cycles.

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Ruddiman (2007)

  • The primary energy to our planet is the sun
  • The solar energy that reaches Earth’s surface depends on latitudinal, position on the planet, internal solar processes, changes in Earth's orbit
  • Our climate system is defined by a complex series of interactions and feedbacks
  • An external change in any one component will affect the rest

​

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Biological Pump & Solubility

Ocean upwelling

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Biological Pump & Solubility

A balancing act between the upwelling of carbon from the deep ocean and storage of carbon in the ocean through the biological pump and CO2 solubility.

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Orbital Forcing

Small effect on its own

Affects seasons

More tilt, warmer summer, colder winter

Affects when seasons happen in the orbit.

Cold NH Summer, Ice Grows.

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Warm NH Summer, Ice Shrinks

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Orbital Forcing

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Let’s zoom into the last deglacial period

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Ruddiman (2007)

Human Activities

GHG, Land Use Change, etc.

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iceandclimate.nbi.ku.dk

2004: A new Ice Core Lab at OSU is established by Dr. Ed Brook

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2007

384

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iceandclimate.nbi.ku.dk

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384

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2012

iceandclimate.nbi.ku.dk

My daughter was born and I joined the OSU ice core lab.

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384

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2022

2004-2021

110ppb in 17 years

iceandclimate.nbi.ku.dk

2004-2021

28ppm in 17 years

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Thank you!

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Existing attempts at validation of the boron isotope proxy from Foster and Rae (2016) including data from Hoenisch et al. (2009)