Terrestrial uptake due to cooling responsible for low CO2 during

the Little Ice Age

M. Rubino- Seconda Università di Napoli

- CSIRO Oceans and Atmospheric Flagship

• Etheridge D.M. (CSIRO, Australia)• Trudinger, C. (CSIRO, Australia)• Allison C. (CSIRO, Australia)• Rayner P. (Melbourne Uni, Australia)• Steele P. and Langenfelds R. (CSIRO, Australia)• Curran, M. (Australian Antarctic Division)• Mulvaney R. (BAS, UK)• Sturges W.T. (University of East Anglia, UK)• Smith A. (ANSTO, Australia)

Co-authors

Motivations

CMIP4, Friedilingstein et al. (2006)

Motivations

Cox & Jones (2008)

A revised 1000 year atmospheric d13C-CO2 record from Law Dome and South Pole, Antarctica

Rubino et al. (2013)

Geographical distribution of ice core drilling and firn sites

DSS≡DSS0506

DE08

DML

Comparison among different sites

DSS (Law Dome) vs DML: CO2

Double Deconvolution of DML

Two hypotheses

Land use change: Gross Primary Productivity increased because of vegetation regrowth after abandonment of land by farmers due to pandemics

Temperature response: Gross Primary Productivity decreased but respiration decreased more due to the higher temperature dependence of respiration

Carbonyl sulphide (COS): a proxy for GPP

Aydin et al. (2008)

COS: a proxy for GPPFocean + Fanthropogenic + Fbiomass burning = (kOH + kterrestrial)*[COS]

Berry et al. (2013)

+18

Conclusions New CO2 record from DML is consistent with the DSS CO2

record.

New d13C-CO2 record from DML unambiguously confirms that the terrestrial biosphere was the main contributor to the LIA CO2 decrease.

The first modelling of the COS LIA budget suggests that respiration decreased more than photosynthesis due to the temperature decrease.

New sensitivity of the terrestrial carbon cycle to temperature can be estimated.