Mid‐ and late‐Holocene climatic changes: a test of periodicity and solar forcing in proxy‐climate data from blanket peat bogs

Abstract

2001. Mid-and Late-Holocene climatic changes: a test of periodicity and solar forcing in proxy-climate data from blanket peat bogs.ABSTRACT: A wide range of palaeoenvironmental evidence from the Holocene has suggested periodicities in the Earth's climate of 10s to 1000s of years. Identifying these millennial-, centuryand decadal periodicities, and their impacts, is critical in developing a fuller understanding of natural climate variability. Any solar-induced climatic change needs to be distinguished from other causes of natural climate variability and from short-term catastrophic events induced either by external or internal processes. Such events might themselves generate a periodicity, or in combination with other forcing factors they may contribute towards a periodicity (and so spuriously imply a universal and continuing periodicity in the climate record), or they may resonate with a solar-induced periodicity. Here, evidence from peat records for periodicity in climate change over the mid to late Holocene is reviewed and this is followed by a test of the replicability of claimed periodicities using blanket peat data covering the past 2000 yr from four sites in the British Isles. Results suggest that the mires studied do go through phases of being responsive to periodic forcing factors, with ca. 200, ca. 80 and 60-50 yr wavelengths reflected in some data sets. However, the patterns shown are not consistent. This could be the result of local conditions at individual mires (human impact, sensitivity and vegetation succession) or of changes in the strength or nature of global forcing factors. Assessing a solar-mire link remains difficult because the century-scale variations of the Sun show different intervals between solar minima, the durations of which are themselves unequal, and because the proxy-climate data-sets from peat profiles may themselves not be dated with sufficient precision and/or accuracy.

Solar forcing of climatic change during the mid-Holocene: indications from raised bogs in The Netherlands

“…Temporal links between archives of climate change and changes in solar activity have been reported before (e.g., Wijmstra et al, 1984;Blackford and Chambers, 1995;Hong et al, 2000;Bond et al, 2001;Chambers and Blackford, 2001;Magny, 2004), but the chronologies used in these studies often were rather imprecise. With our approach of 14 C wiggle-match dating, peat chronologies become far more precise.…”

“…A temporal link between changes in D 14 C and Holocene climatic changes has been documented by several studies (Blackford and Chambers, 1995;Karlén and Kuylenstierna, 1996;Chambers et al, 1999;Hong et al, 2000;Björck et al, 2001;Bond et al, 2001;Hodell et al, 2001;Neff et al, 2001;Magny, 2004), while other studies report climate cycles with periodicities close to those of solar variability (e.g., Wijmstra et al, 1984;Chambers et al, 1999;Ram and Stolz, 1999;Chambers and Blackford, 2001). However, the chronologies obtained in these studies often were rather imprecise.…”

Atlantic to Urals – the Holocene climatic record of Mid-Latitude Europe

“…1100, 800, 600 and 200 years, amongst others, have been recognised from the peat bog record, and these may be linked to solar forcing and oceanic changes (Barber et al 1994;Chambers et al 1997;Hughes et al 2000;Chambers and Blackford 2001;Langdon and Barber 2001). It is clear that the teleconnections in climate changes over the last 2000 years between sites some 300 km apart and at different altitudes can also be found during earlier times between sites across a wide area of oceanic Mid-Latitude Europe.…”

“…500 years, and interact with the thermohaline circulation of the North Atlantic (Vidal and Arz, this volume) to influence sea-surface temperatures, depression tracks and other factors which are then expressed in the climate over Europe (Snowball et al, this volume). There is also evidence of solar variability in the ocean records, which may be reflected in sensitive terrestrial ecosystems (Bond et al 2001;Chambers and Blackford 2001;.…”

Cyclic sedimentation pattern in Lake Veetka, southeast Estonia: a case study

“…Several mires in northwest Europe showed cyclic humification ranging in time from a century to a millennium, triggered by changes in hydrological and climatic conditions (Chambers & Blackford, 2001;Väliranta et al, 2007), precipitation being the prime controlling factor (Charman et al, 2009). Biological and palaeohydrological records from the Central Estonian Männikjärve bog (58°52´N, 26°15´E) also documented an alternation of drier and wetter conditions (Sillasoo et al, 2009) over an average of 380 years.…”