UK Climate During The Common Era

Palaeoclimatic data provide the quantitative information and context required for the study and attribution of natural- and anthropogenic-forced climatic variability. If our society is to appropriately address the future challenges of climate change, it is of vital importance that we know how the climate of the United Kingdom (UK) has varied in the past. Only with this information will it be possible to formulate effective policy and critically evaluate the performance of the Earth system models that increasingly underpin UK climate policy.

Currently proxy-specific limitations severely constrain the number of reliable temperature or precipitation reconstructions for these islands. This is especially true of numerically verifiable reconstructions of late Holocene (<2kya) climate. Remarkably, despite a long established tradition of palaeoclimatology, we have not established, with any confidence, the frequency of seasonal extremes, or indeed the levels of temperature and precipitation of the Roman, Mediaeval, or "Little Ice Age" periods; and importantly, we cannot therefore make comparisons with recent climate. As a consequence, policy makers, researchers and the public are forced to rely upon lower-confidence reconstructions or outdated, uncalibrated low-frequency records based upon anecdotal evidence. This is wholly inappropriate for both modern numerical analyses and robust evidence-based decision making.

Our new, but rigorously tested method, is based upon the stable carbon and oxygen isotope analysis of precisely-dated oak tree-rings. These data are capable of capturing past climatic variability (both temperature and precipitation) with a high degree of numerical accuracy. We can therefore address this research gap for the UK and other under-represented, temperate mid-latitude regions.

This project will develop 2000 year numerically verifiable reconstructions of summer temperature and precipitation, with defined confidence intervals. Such data are urgently required by the research community and will be incorporated into national and continental-scale palaeoclimate composites, enhancing their regional relevance and reconstructive skill. We will deliver a quantitative reference climatology that will mark a step-change in UK palaeoclimatology, moving from reliance upon seminal, but outdated research (e.g. Lamb 1966), to a new numerical and tightly constrained understanding of past climate.

Understanding the natural variability and controls that directly affect UK climate is vital for effective climate forecasting, policy formulation and resource management. We will ensure scientific and social impact from our research through dissemination and access to our data targeting beneficiaries in; science and academia, policy and governance, industry and the engaged public.

Scientific and Academic Beneficiaries: Primary beneficiary groups include researchers in climate modelling, palaeoclimatology, geography, Earth science, hydrology, history and archaeology. In addition to high-impact research publications, international scientific conferences and established project partnerships, we will make our data freely available to the scientific community to ensure impact far beyond the scope and duration of the project and ensure that data are accessible across this diverse group of academic beneficiaries. Our robust reconstructions of past climate, with annual resolution and with statistically defined confidence covering the last two millennia for highly populated mid-latitudes will start to address existing geographical bias in climate science and will therefore be extremely valuable.

Policy Makers: Reliable modelling of the future response of UK climate to greenhouse forcing requires a realistic understanding of the natural variability of the climate, both in terms of unforced internal variability and in the magnitude of response to natural forcing events including major volcanic eruptions and changes in total solar irradiance. Realistic estimates of the natural variability in terms of the magnitude and frequency of extremes is particularly critical. Our reconstructions will provide this information for UK summer climate, both through a dedicated policy briefing document (structured to contextualise UKCP18 findings) and as an open-access resource to help reduce the uncertainty of climate modelling. Improved prediction will enable policy makers to use these data to formulate more effective policy and strategic planning (for example in agriculture, drought forecasting and water-resource management, energy and health-care provision).

Public Access and Societal Impact: Weather and oak trees are deeply rooted in the British cultural identity. This research has significant potential for enriching culture and quality of life through innovative communication and engagement strategies. In addition to standard outreach activities we will focus on two beneficiary groups to ensure impact.

1. Working in partnership with The National Trust, the largest voluntary conservation organisation in Europe and largest membership organisation in the UK, we will develop a "whispering trees" website linked to specific trees and timbers identifiable at National Trust properties (from where some of the material for our reconstructions has been sourced) via strategically located QR coded tags. We will engage with the public throughout this project and communicate our work through non-specialist publications and employ smartphone technologies to reach the environmentally i-curious.

2. School students - We will work with Dr Sylvia Knight, the Head of Education at the Royal Meteorological Society to develop educational and public outreach resources to be used at GCSE level in Science and Geography. The aims are to provide interactive tools which show how climate has changed over time, allow recent climate to be compared with climate prior to industrialisation, and the impact of natural and anthropogenic forcing. Through this partnership we will develop the "Great Climate Jig-Saw" a public outreach exhibit which we will showcase at National public events (e.g. British Science Festival, Oriel Science, British Association of Young Scientists, Welsh National Eisteddfod Gwyddon Lle etc.) with the aim of engaging the public and under-represented groups in UK climate change research.