The Holocene (12 000 years ago until now?) was a period where temperature was relatively constant and the volume of ice at the caps was relatively stable. How much this climate varied naturally is a key issue in understanding the human influence on today’s climate.

Why research climate changes in the Holocene?

There were several climatic events during the Holocene (e.g. 9 200 and 500 years ago), but the largest temperature irregularity, discovered from δ¹⁸O in Greenland ice cores, was at about 8200 years ago. At this time, there was a catastrophic release of fresh water from glacial lakes Agassiz and Ojibway in Canada, which is thought to have resulted in a 1.5 to 2°C cooling of the North Atlantic. This slowed the Meridional Overturning Circulation (MOC) in the North Atlantic by about 40%, cooling the land at high latitudes for a geologically short interval of time (100–200 years).

This event (also known as 'the 8.2 event'), and a similar one at 9200 years ago ('the 9.2 event'), is believed to be a useful comparison for future changes to the North Atlantic system, given the prediction that, as the ice sheets melt in the coming decades, large quantities of freshwater are expected to be released into the North Atlantic. A better understanding of the events in the Holocene is therefore needed to help predict potential consequences to the North Atlantic system.

What research is BGS doing?

The BGS Climate Change Team is studying core from the central Irish Sea to see how the environment was influenced by climatic changes in the Holocene.

BGS borehole 89/15 (pictured right) is from a site in the central Irish Sea. The site thought to be well situated to monitor changes to British and Irish climate during the climatic events 9200 and 8200 years ago (and possibly the 'Little Ice Age' as well).

The core is 38 metres long and was drilled through Holocene deposits. This is believed to be one of the most expanded marine Holocene sections in Europe (other cores from this time are less than 38 metres thick providing a more compressed view of this period; this core is such that information about the Holocene climate can be extracted at about ten-year resolution).

To understand changes in temperature, acidity and source of the water mass, the following analyses will be carried out:

• radiocarbon dating
• δ¹⁸O and δ¹³C
• Mg/Ca, Sr/Ca and ratios

Other analyses include bulk sediment U^K_37' analysis for sea surface temperature and micropalaeontological assemblage (pictured below) study for changes in ecology, water masses, and stratification (layering of salinity, oxygenation, density and temperature within sea water).

Through this study, and by comparison with other UK boreholes, we hope to measure oceanic change during the Holocene and, in turn, the potential effect of North Atlantic MOC disturbances and cooling to the Irish Sea and UK continental shelf.

Further reading

Austin, W.E.N. & Scourse, J.D. 1997. Evolution of seasonal stratification in the Celtic Sea during the Holocene, Journal of the Geological Society, London, 154, 249-256.

Dickson, C, & Whatley, R. 1996. The biostratigraphy of a Holocene borehole from the Irish Sea. 145-148. In: Keen, MC (Ed.) Proceedings of the 2nd European Ostracodologists’ Meeting, University of Glasgow, 23rd-27th July 1993.

Fleitmann D., Mudelsee, M., Burns, S. J., Bradley, R. S., Kramers, J. & Matter, A. 2008. Evidence for a widespread climatic anomaly at around 9.2 ka before present, Paleoceanography, 23, PA1102.

Marshall, J. D., Lang, B. Crowley, D. F., Weedon, G. P., van Calsteren, P., Fisher, E. H., Holme, R., Holmes, J. A., Jones, R. T., Bedford, A., Brooks., S. J., Bloemendal, J. Kiriakoulakia, K. and Ball, J. D. (2007), Terrestrial impact of abrupt changes in the North Atlantic thermohaline circulation: Early Holocene, UK, Geology, 35, 639– 642.

Rohling, E. J. & Pälike, H. 2005. Centennial-scale climate cooling with a sudden cold event around 8,200 years ago, Nature, 434, 975– 979.

Scourse, J.D., Austin, W.E.N., Long, B.T., Assinder, D.J. and Huws, D. 2002. Holocene evolution of seasonal stratification in the Celtic Sea: refined age model, mixing depths and foraminiferal stratigraphy. Marine Geology, 191, 119-145.

Contact

Contact Dr Ian Wilkinson or Dr Sev Kender for further information.

• What was the climate like in our geological past?
• What is the Anthropocene?
• What was the climate like in the Holocene?
• What was the climate like in the Pliocene?
• High latitude climate change in the Pliocene Antarctic
• Computer modelling past climates
• NERC Isotope Geosciences Lab and climate change

• NOCS MOC
• Was there a Little Ice Age and a Medieval Warm Period?
• The Little Ice Age and Scotland

• Dr Sev Kender

• Tepexpan Palaeoindian site, Basin of Mexico: multi-proxy evidence for environmental change during the Late Pleistocene-Late Holocene
• Lateglacial-Holocene shoreface progradation offshore Eastern Scotland : a response to climatic and coastal hydrographic change
• Multidisciplinary monitoring and modelling to understand the Holocene landscape evolution of a small upland catchment
• The palaeohydrological evolution of Lago Chungara (Andean Altiplano, northern Chile) during the Lateglacial and early Holocene using oxygen isotopes in diatom silica
• A multiproxy palaeolimnological investigation of Holocene environmental change, between c. 10 700 and 7 200 years BP, at Holebudalen, southern Norway
• Assessing δ¹³C and C/N ratios from organic material in archived cores as Holocene sea level and palaeoenvironmental indicators in the Humber Estuary, UK
• Seasonality of δ¹³C and C/N ratios in modern and mid-Holocene sediments in the Severn Estuary Levels, SW Britain
• Holocene climate change in the eastern Mediterranean region: a comparison of stable isotope and pollen data from Lake Golhisar, southwest Turkey
• Assessment of δ¹³C and C/N ratios in bulk organic matter as palaeosalinity indicators in holocene and lateglacial isolation basin sediments, northwest Scotland
• Foraminifera and ostracoda in the St Andrew's Bay member (Forth Formation: Holocene), offshore Montrose