WUWT tipsar om en studie som publicerats i Quaternary Science Reviews. Studiens resultat visar att Arktis tycks periodvis ha varit isfritt sommartid under tidig Holocen. Koldioxidnivån antas då ha legat på ca 260 ppm, alltså är det inte koldioxidhalten i atmosfären som ligger bakom detta försvinnande av istäcket.
En av studiens författare är professor Martin Jakobsson, maringeolog från Stockholms universitet.
Nedan mer info om studien.
New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling
Martin Jakobsson (a), Antony Long (b), Ólafur Ingólfsson (c), Kurt H. Kjær (d) and Robert F. Spielhagen (e)
a Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden
b Department of Geography, Durham University, Science Site, South Road, Durham DH1 3LE, UK
c Faculty of Earth Sciences, University of Iceland, Is-101 Reykjavik, Iceland
d Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen, Denmark
e Academy of Sciences, Humanities and Literature, Mainz, and Leibniz Institute of Marine Sciences, IFM-GEOMAR, Wischhofstr. 1-3, D-24148 Kiel, Germany
Accepted 26 August 2010.
Available online 2 October 2010.
Terrestrial and marine geological archives in the Arctic contain information on environmental change through Quaternary interglacial–glacial cycles. The Arctic Palaeoclimate and its Extremes (APEX) scientific network aims to better understand the magnitude and frequency of past Arctic climate variability, with focus on the “extreme” versus the “normal” conditions of the climate system. One important motivation for studying the amplitude of past natural environmental changes in the Arctic is to better understand the role of this region in a global perspective and provide base-line conditions against which to explore potential future changes in Arctic climate under scenarios of global warming. In this review we identify several areas that are distinct to the present programme and highlight some recent advances presented in this special issue concerning Arctic palaeo-records and natural variability, including spatial and temporal variability of the Greenland Ice Sheet, Arctic Ocean sediment stratigraphy, past ice shelves and marginal marine ice sheets, and the Cenozoic history of Arctic Ocean sea ice in general and Holocene oscillations in sea ice concentrations in particular. The combined sea ice data suggest that the seasonal Arctic sea ice cover was strongly reduced during most of the early Holocene and there appear to have been periods of ice free summers in the central Arctic Ocean. This has important consequences for our understanding of the recent trend of declining sea ice, and calls for further research on causal links between Arctic climate and sea ice.
Det hade varit mycket intressant att få höra vad Martin Jakobsson anser om studiens resultat kontra dagens issituation i Arktis.