Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as 10 Be and 14 C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different 10 Be ice core records from Greenland and Antarctica with the global 14 C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution 10 Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate.

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One of the major difficulties in paleontology is the acquisition of fossil data from the 10% of Earth's terrestrial surface that is covered by thick glaciers and ice sheets. Here we reveal that DNA and amino acids from buried organisms can be recovered from the basal sections of deep ice cores and allow reconstructions of past flora and fauna. We show that high altitude southern Greenland, currently lying below more than two kilometers of ice, was once inhabited by a diverse array of conifer trees and insects that may date back more than 450 thousand years. The results provide the first direct evidence in support of a forested southern Greenland and suggest that many deep ice cores may contain genetic records of paleoenvironments in their basal sections.The environmental histories of high latitude regions such as Greenland and Antarctica are poorly understood because much of the fossil evidence is hidden below kilometer thick ice sheets (1-3). Here, we test the idea that the basal sections of deep ice cores can act as archives for ancient biomolecules and show that these molecules can be used to reconstruct significant parts of the past plant and animal life in currently ice covered areas.The samples studied come from the basal impurity rich (silty) ice sections of the 2km long Dye 3 core from south-central Greenland (4), the 3km long GRIP core from the summit of the UKPMC Funders Group Author Manuscript UKPMC Funders Group Author ManuscriptGreenland ice sheet (5), and the Late Holocene John Evans Glacier on Ellesmere Island, Nunavut, northern Canada (Fig. 1A,B). The latter sample was included as a control to test for potential exotic DNA because the glacier has recently overridden a land surface with a known vegetation cover (6). As an additional test for long-distance atmospheric dispersal of DNA, we included five control samples of debris-free Holocene and Pleistocene ice taken just above the basal silty samples from the Dye 3 and GRIP ice cores (Fig. 1B). Finally, our analyses included sediment samples from the Kap København Formation from the northernmost part of Greenland, dated to 2.4 million years before present (Ma BP) (1,2).The silty ice yielded only few pollen grains and no macrofossils (7). However, the Dye 3 and John Evans Glacier silty ice samples showed low levels of amino acid racemization (Fig. 1A, insert), indicating good organic matter preservation (8). Therefore, following previous success with permafrost and cave sediments (9-11), we attempted to amplify ancient DNA from the ice. This was done following strict criteria to secure authenticity (12-14), including covering the surface of the frozen cores with plasmid DNA to control for potential contamination that may have entered the interior of the samples through cracks or during the sampling procedure (7). PCR products of the plasmid DNA were obtained only from extracts of the outer ice scrapings but not from the interior, confirming that sample contamination had not penetrated the cores.We could reproducibly PCR amplify short ampli...