Connecting the Greenland ice-core and U/Th timescales via cosmogenic radionuclides: testing the synchroneity of Dansgaard–Oeschger events Climate of the Past DOI 10.5194/cp-14-1755-2018 20 November 2018 The last glacial period was characterized by a number of rapid climate changes seen, for example, as abrupt warmings in Greenland and changes in monsoon rainfall intensity. However, due to chronological uncertainties it is challenging to know how tightly coupled these changes were. Here we exploit cosmogenic signals caused by changes in the Sun and Earth magnetic fields to link different climate archives and improve our understanding of the dynamics of abrupt climate change. Read more
A 900-year New England temperature reconstruction from in situ seasonally produced branched glycerol dialkyl glycerol tetraethers (brGDGTs) Climate of the Past DOI 10.5194/cp-14-1653-2018 7 November 2018 We measured biomarker production over a year in a small inland lake in the northeastern USA. Understanding biomarkers in the modern environment helps us improve reconstructions of past climate from lake sediment records. We use these results to interpret a 900-year decadally resolved temperature record from this lake. Our record highlights multi-decadal oscillations in temperature superimposed on a long-term cooling trend, providing novel insight into climate dynamics of the region. Read more
Wet avalanches: long-term evolution in the Western Alps under climate and human forcing Climate of the Past DOI 10.5194/cp-14-1299-2018 11 September 2018 In the context of a warming climate, mountain environments are especially vulnerable to a change in the risk pattern. Our study focuses on the past evolution of wet avalanches, likely triggered by warmer temperatures destabilizing the snow cover. In the last 3300 years we observed an increase of wet avalanche occurrence related to human activities, intensifying pressure on forest cover, as well as favorable climate conditions such as warmer temperatures coinciding with retreating glacier phases. Read more
Climate impact on the development of Pre-Classic Maya civilisation Climate of the Past DOI 10.5194/cp-14-1253-2018 20 August 2018 We present two new palaeoclimatic records for the central Maya lowlands, adding valuable new insights to the impact of climate change on the development of Maya civilisation. Lake Tuspan’s diatom record is indicative of precipitation changes at a local scale, while a beach ridge elevation record from the world’s largest late Holocene beach ridge plain provides a regional picture. Read more
Testing the consistency between changes in simulated climate and Alpine glacier length over the past millennium Climate of the Past DOI 10.5194/cp-14-1119-2018 9 August 2018 Glaciers provide iconic illustrations of past climate change, but records of glacier length fluctuations have not been used systematically to test the ability of models to reproduce past changes. One reason is that glacier length depends on several complex factors and so cannot be simply linked to the climate simulated by models. This is done here, and it is shown that the observed glacier length fluctuations are generally well within the range of the simulations. Read more
Aromatic acids in an Arctic ice core from Svalbard: a proxy record of biomass burning Climate of the Past DOI 10.5194/cp-14-637-2018 23 May 2018 This study presents organic acid levels in an ice core from Svalbard over the past 800 years. These acids are produced from wildfire emissions and transported as aerosol. Organic acid levels are high early in the record and decline until the 20th century. Siberia and Europe are likely the primary source regions of the fire emissions. The data are similar to those from a Siberian ice core prior to 1400 CE. The timing of the divergence after 1400 CE is similar to a shift in North Atlantic climate. Read more
Random and externally controlled occurrences of Dansgaard–Oeschger events Climate of the Past DOI 10.5194/cp-14-609-2018 16 May 2018 The climate of the last glacial period was frequently interrupted by rapid warming events, the cause of which is still unknown. One open question is whether the occurrence of events is random or externally controlled. We studied the temporal characteristics of warm and cold phases using statistical null models and find that they are well described as random processes modulated by two different external climate factors. This may help distinguish physical mechanisms for rapid climate change. Read more
Technical note: Open-paleo-data implementation pilot – the PAGES 2k special issue Climate of the Past DOI 10.5194/cp-14-593-2018 3 May 2018 We explain the procedure used to attain a high and consistent level of data stewardship across a special issue of the journal Climate of the Past. We discuss the challenges related to (1) determining which data are essential for public archival, (2) using data generated by others, and (3) understanding data citations. We anticipate that open-data sharing in paleo sciences will accelerate as the advantages become more evident and as practices that reduce data loss become the accepted convention. PAGES 2k special issue">Read more
Moving beyond the age–depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera Climate of the Past DOI 10.5194/cp-14-515-2018 20 April 2018 Palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid climate change, but only a small proportion of the ocean is suitable for such reconstructions using the existing state of the art, i.e. the age–depth approach. We use dual radiocarbon (14C) and stable isotope analysis on single foraminifera to bypass the long-standing age–depth approach, thus facilitating past ocean chemistry reconstructions from vast, previously untapped ocean areas. Read more
A 305-year continuous monthly rainfall series for the island of Ireland (1711–2016) Climate of the Past DOI 10.5194/cp-14-413-2018 27 March 2018 This work reconstructs a continuous 305-year rainfall record for Ireland. The series reveals remarkable variability in decadal rainfall – far in excess of the typical period of digitised data. Notably, the series sheds light on exceptionally wet winters in the 1730s and wet summers in the 1750s. The derived record, one of the longest continuous series in Europe, offers a firm basis for benchmarking other long-term records and reconstructions of past climate both locally and across Europe. Read more