Late Holocene temperature reconstruction from Hawes Water northwest England using chironomid analysis

The proposed research would use chironomid midges from the sediments of Hawes Water, a small hard water lake in northwest England, to reconstruct summer temperatures for the past 5,000 years. Chironomids are one of the most widely used proxies for temperature reconstruction as they rapidly respond to even small changes in summer air temperatures. They are ideal for palaeo studies as the larval heads preserve well in sediments and many chironomid taxa are sensitive to a particular temperature range The record would provide temperatures at a resolution of approximately 30 years and would be the first high resolution quantitative record of climate change during this period from England and the only high resolution record in the UK.

Past research at Hawes Water has shown the sensitivity of the site to climate changes, particularly those induced by changes in North Atlantic circulation (Marshall et al., 2007). Temperature records are available from Hawes Water for the period from ca. 14,500 to 5,000 years before 2000 (b2k). Until recently it had been thought that during the later Holocene (5,000 b2k to present) the increasing influence on the midge assemblage of human induced changes in lake water (particularly pH, nutrient and oxygen status) may override and confuse the temperature effect, thus affecting the reconstructions and making them inaccurate (see Velle et al., 2010 for discussions). However, comparisons of chironomid inferred temperature from Speke Hall Lake in Liverpool (an enriched polluted low oxygen lake) with local instrumental records for the last 80 years demonstrate that a chironomid-based temperature inference model can produce reliable estimates of mean July air temperatures, even from a lake experiencing large changes in heavy metal and sulphur pollution and nutrient status (Lang et al., imminent submission). The project will therefore extend the Hawes Water record into this Later Holocene period to produce the first complete high resolution summer temperature record from a single archive for the UK for the last 14500 years.


The research would then use the reconstructed temperatures together with an existing stable oxygen isotope record from the site to reconstruct the oxygen isotope values of the paleao lake water (ISOCHIRO method of Marshall et al., 2007) for the last 5,000 years. The isotopic value of palaeo lake water directly links to that of precipitation and that of the source water from which it was evaporated (ie the north east Atlantic) and Marshall et al (2007) have shown that changes in the oxygen isotope values of early Holocene lake waters at Hawes Water were a direct downstream response to changes in North Atlantic circulation due to meltwater influxes from pro glacial lakes in America and Fenno-scandianavia. Results from this research will indicate any changes which may have taken place in the north eastern Atlantic surface waters during the later Holocene.


Detailed examination of the two new records will give insight into the drivers of late Holocene climate change. Comparison of the isotopic meteoric water record and the temperature record will indicate the extent of the influence of oceanic changes on terrestrial climate and the extent to which climate change may be attributed to other climate drivers e.g. variations in solar irradiation. Completion of the full Holocene temperature record at Hawes Water will enable time series analysis which will indicate as to whether the inherent cyclicity which has been identified within the Holocene climate in some oceanic records (Bond et al., 1997) is also visible in terrestrial climate.

Please see Case for Support for full reference details.

Impact Summary
This project will complete the temperature record for the last 15500 years. As a complete record from one archive, this has considerable significance for the interpretation and use of proxy climate and environmental change records from cool temperate regions. This allows confident visualisatin of temperature changes by practioners, planners and end-users, enabling them to develop strategies and policies for adaptation to climate in the future.

The community benefiting from the project is broad and the implications which may be derived from a high resolution temperature curve for understanding climate, sedimentary and ecological systems are significant. Firstly, other educators, in particular in secondary schools and Further Education colleges, and those involved in curriculum design and development e.g. the Geographical Association (GA), will be involved in workshops to disseminate findings. The GA has already indicated their support and Worsley has published in the pedagogic/teaching literature on the impacts of climate change on human communities. Secondly, local councils will benefit from the additional knowledge and understanding of the timescales involved in temperature and subsequent environmental shifts. Local coastal groups, with AW (via the North West Coastal Forum which includes Natural England, National Trust, Defra, the Environment Agency, the Sefton Coast Partnership and Sefton Metropolitan Borough Council), have worked on the impacts of climate change on coastal environments through Defra's Pathfinder programme and the EU's IMCORE project. In addition, local civic, historical and geological societies have expressed interest; AW and BL have given talks to groups in Cumbria, Lancashire and Merseyside.

The work will build significantly upon these links already established via workshops, seminars, and a website specifically designed to lead with the updated temperature records and its significance to terrestrial and coastal environmental changes, in order to inform public policy, particularly in coastal and lowland management.

The Regionally Important Geological/Geomorphogical Sites Group (RIGS) have also expressed interest in the work. Following initial meetings, further collaborative work with the Lancashire RIGS group is planned in the form of site visits and workshops to review the data and their implications for understanding local landform development, responses of sedimentary systems to climate change e.g. soil inwash, and.
There are no immediate/direct economic impacts but the longer term implications of the temperature curve for local and regional planners and policy makers, especially those involved in coastal, estuarine and flood defence strategies, are clear. Current work in developing long term strategies for adapting to rapid climate change and to militate against the negative impacts of such changes is at the forefront of regional and local planning policies. Understanding the nature of temperature changes is important not only to those managing landforms, such as Natural England and the Environment Agency, but also to regional tourism, a multi-million pound economy based principally on the Lancashire and South Cumbrian coasts.