New paper finds CO2 spiked to levels higher than the present during termination of last ice age

A new paper published in Quaternary Science Reviews reconstructs CO2 levels during the termination of the last ice age and finds CO2 spiked to levels near or even exceeding those of the present, obviously without any human influence. According to the authors, "The record clearly demonstrates that [CO2 levels were] significantly higher than usually reported for the Last [Glacial] Termination," with levels of up to ~425 ppm about 12,750 years ago, which exceeds the present CO2 concentration of 395 ppm. 

Left graph shows CO2 concentrations varied dynamically between ~220-425 ppm from 14,000-11,500 years ago. Ice core comparison is shown at right.

Related: From the paper by EG Beck showing chemical measurements of CO2 levels of up to ~480 ppm during the 1800's 

Related: New blockbuster paper finds man-made CO2 is not the driver of global warming

Stomatal proxy record of CO₂ concentrations from the last termination suggests an important role for CO₂ at climate change transitions

• Margret Steinthorsdottir^a, , , 
• Barbara Wohlfarth^a, 
• Malin E. Kylander^a, 
• Maarten Blaauw^b, 
• Paula J. Reimer^b

• ^a Department of Geological Sciences, Bolin Centre for Climate Research, Stockholm University, SE 109 61 Stockholm, Sweden
• ^b School of Geography, Archaeology and Palaeoecology, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland, United Kingdom

• http://dx.doi.org/10.1016/j.quascirev.2013.02.003, How to Cite or Link Using DOI

• Permissions & Reprints

---

Abstract

A new stomatal proxy-based record of CO₂ concentrations ([CO₂]), based on Betula nana (dwarf birch) leaves from the Hässeldala Port sedimentary sequence in south-eastern Sweden, is presented. The record is of high chronological resolution and spans most of Greenland Interstadial 1 (GI-1a to 1c, Allerød pollen zone), Greenland Stadial 1 (GS-1, Younger Dryas pollen zone) and the very beginning of the Holocene (Preboreal pollen zone). The record clearly demonstrates that i) [CO₂] were significantly higher than usually reported for the Last Termination and ii) the overall pattern of CO₂ evolution through the studied time period is fairly dynamic, with significant abrupt fluctuations in [CO₂] when the climate moved from interstadial to stadial state and vice versa. A new loss-on-ignition chemical record (used here as a proxy for temperature) lends independent support to the Hässeldala Port [CO₂] record. The large-amplitude fluctuations around the climate change transitions may indicate unstable climates and that “tipping-point” situations were involved in Last Termination climate evolution. The scenario presented here is in contrast to [CO₂] records reconstructed from air bubbles trapped in ice, which indicate lower concentrations and a gradual, linear increase of [CO₂] through time. The prevalent explanation for the main climate forcer during the Last Termination being ocean circulation patterns needs to re-examined, and a larger role for atmospheric [CO₂] considered.

---

Highlights

► A stomatal proxy-based CO₂ record from the Last Termination is presented. ► The stomata based CO₂record is much more dynamic than ice core-based CO₂ records. ► CO₂ first increases abruptly before decreasing at cooling transitions and vice versa.