Key traits of living fossil Ginkgo biloba are highly variable but not influenced by climate – Implications for palaeo-pCO2 reconstructions and climate sensitivity
2022 (English)In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 211, p. 103786-103786, article id 103786Article in journal (Refereed) Published
Abstract [en]
The Ginkgoales, including the ‘living fossil’ Ginkgo biloba, are an important group for stomata-based palaeo-pCO2 reconstructions, with long evolutionary lineages and an extensive, abundant fossil record. The stomatal proxy for palaeo-pCO2 can improve our understanding of the exact relationship between pCO2 and temperatures – Earth's climate sensitivity: a key measure of global warming by pCO2. However, pCO2 records from future climate analogues in the past, such as the mid-Miocene Climatic Optimum, seemingly underestimate pCO2 – climate models cannot simulate the past temperatures with the only moderately elevated pCO2 reconstructed by proxies. Either climate sensitivity must have been elevated, which has implications for future climate forecasts, or proxies underestimate pCO2 due to additional environmental factors. Here we tested whether climate conditions impact stomatal parameters and thus pCO2 reconstruction on a large global database of G. biloba leaves from all continents except Antarctica, spanning 12 climate zones. We reconstructed ambient pCO2 using three stomatal proxy methods (stomatal ratio, transfer functions, Franks gas exchange model) and one stomata-independent isotope-based proxy for comparison (C3 proxy). We found that the stomatal proxy methods reconstructed ambient pCO2 reasonably well and uniformly, but that the C3 proxy underestimated pCO2. All the investigated stomatal parameters displayed an unexpectedly large variability, but no significant relationship with temperature, precipitation, or seasonality. Based on these results, the stomatal proxy is not influenced by climate and specifically does not systematically underestimate pCO2 under high temperatures. Climate sensitivity was likely instead elevated during past global warming episodes, an urgent consideration in climate forecasts for our rapidly warming Earth.
Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2022. Vol. 211, p. 103786-103786, article id 103786
Keywords [en]
Climate sensitivity, Paleo-pCO2 reconstructions, Stomatal proxy, Climate change, Ginkgo, Natural variability
National Category
Other Earth and Related Environmental Sciences
Research subject
The changing Earth
Identifiers
URN: urn:nbn:se:nrm:diva-4910DOI: 10.1016/j.gloplacha.2022.103786OAI: oai:DiVA.org:nrm-4910DiVA, id: diva2:1715955
Funder
NERC - the Natural Environment Research Council, NE/R001324/1Carl Tryggers foundation , CTS 18:167Swedish Research Council, 2016 04905German Research Foundation (DFG), 443701866NERC - the Natural Environment Research Council, NE/T00392/1
Note
M.S. would like to acknowledge funding from the Swedish Research Council, who supported this research with grant nr. NT7-2016 04905, and from the Bolin Centre for Climate Research, Stockholm University. B.H.L acknowledges funding from the NERC (grant nr. NE/R001324/1 and NE/T00392/1). P.E.J. is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project nr. 443701866. T.S. is supported by funding from the Carl Trygger Foundation postdoctoral grant (contract CTS 18:167).
2022-12-042022-12-04Bibliographically approved