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MILLENNIUM - European Climate of the Last Millennium

Summary information

Funding:FP6 - Integrated Project
Total cost:15100000
Ec contribution:12600000
Start date:2006-01-01
End date:2010-10-31
Duration:60 months
Coordinator:Danny McCarroll (
Organisation:University of Wales Swansea - United Kingdom
Keywords:Climate variability; multi-proxy approach; earth sciences, environmental protection; stable isotopes
Project name:MILLENNIUM - European Climate of the Last Millennium
Project summary:Abstract
Millennium will answer one of the most critical questions in climate research: does the magnitude and rate of 20th Century climate change exceed the natural variability of European climate over the last millennium? Existing climate reconstructions rely on inadequate data and underestimate variability. Improved GCM parameterization requires more accurate reconstructions and integrated modelling. We will supply high-resolution chronologies that capture the magnitude and rate of change and the magnitude and frequency of extreme events over the last 1.000 years. Our multi-disciplinary team will use innovative and developing technologies to extract quantitative palaeoclimate information from documentary and natural archives, including trees, lakes, mires and ice cores. A multi-proxy approach provides seasonal palaeoclimate signals with quantified precision. Advances in dating allow us, for the first time, to place terrestrial and marine proxy records on the same timescale, allowing lead and lag relationships in ocean-atmosphere forcing to be captured. Annually banded seashells will be cross-dated like tree rings, and tephra-rich sediments used to construct a marine chronology independent of P14PC dating. This can be used to reconstruct changes in ventilation linked directly to the strength of North Atlantic circulation. Millennial reconstructions of European climate, at a range of scales, will define whether recent climate change is unusual in the context of past variability. Millennium proxy-based reconstructions will be fused with a hierarchy of models, run over both millennium and century time scales using a purpose-built PC cluster and the huge resources of the distributed computing network. Integrated hind- and forecast modelling, (using HadCM3) will allow us to test whether current empirically reconstructed climate records based on regression methods underestimate climate sensitivity or if current GCM simulations give overestimates.

Millennium has a single clear objective: to determine with quantifiable precision whether the magnitude and rate of 20PthP Century climate change exceeds the natural variability of European climate over the last millennium. To do this the project will use the very best documentary, biological and sedimentary archives available across Europe and apply the most powerful techniques to extract palaeoclimate signals. By harnessing some of the best laboratory facilities available we will produce multi-proxy climate reconstructions of unparalleled accuracy and precision. Combined with existing instrumental and proxy palaeoclimate data, our results will allow us to model the past and future impacts of anthropogenic climate forcing using realistic patterns of natural climate variability across Europe.

The Millennium project will achieve six aims:
- It will produce a database of the best data on past climate;
- It will produce new millennial-length palaeoclimate data using the most powerful and innovative methods;
- It will combine the existing and new data to reconstruct the climate of Europe for the last one thousand years at a range of spatial scales;
- It will use the reconstructions to define the natural variability of European climate, over both space and time, and taking account of changes in seasonality;
- It will test the ability of the most commonly used climate model to reproduce the magnitude of natural climate variability in the past;
- It will predict the probability of European climate passing critical thresholds, taking full account of the natural variability as well as greenhouse forcing.

To place recent climate change in a longer term context, several studies have developed millennial length, annually resolved reconstructions of northern hemispheric temperatures. However, despite the high profile status of some of these data-sets, they are limited for a variety of reasons:
- Such time-series provide only a large-scale picture of the mean state of one climate parameter - i.e. mean temperature. The spatial complexity of climate change cannot be assessed from these data;
- The fidelity/robustness of these reconstructions quickly diminishes back in time as very few proxies were included in the early portions of these series;
- Methods used to develop these reconstructions can potentially underestimate the temperature amplitude change over the whole millennium. A more precise assessment of the absolute reconstructed temperature amplitude change is needed to help quantify the relative influences of forcing mechanisms in climate models;
- Due to the strong bias to tree ring-width data, the reconstructions are also likely biased to the summer season, despite the fact that greatest recent changes have been observed in the winter months.

There is therefore a need for complementary investigations at small and intermediate scales with the expressed aim of reconstructing other climatic parameters (e.g. precipitation) and not just temperature. The record breaking central European floods in 2002 and the widespread European drought in 2003, demonstrate the need for a better understanding of precipitation variability in this region. The Millennium project will focus its investigations on Europe where previous research has shown a more varied climate compared to the largescale northern hemisphere reconstructions. The project is built on the rationale that a multi-proxy research approach represents the most productive route towards understanding climate variability, and more specifically for placing the 20th and 21st century climates in the context of the last millennium.

Europe is unique in that there exist long high-quality instrumental records with which assessment of proxy series can be made. This project will not only utilise existing proxy records (e.g. tree-ring and documentary sources), but will emphasise the development of isotopic tree-ring records as well as incorporating a range of new exciting proxy sources (e.g. isotopic records from molluscs, high resolution sedimentary archives and Alpine ice cores). The resulting multi-proxy data-base will not only be rigorously calibrated and furnished with realistic error estimates, but separate calculations for specific parameters, regions, times and time-scales will also be developed. From these data the project will provide the best available information on characteristic modes and magnitudes of natural climate variability for comparison with the natural forcing histories and outputs from climate models. The important questions about the nature, and the significance, of recent climate change can be addressed in separate model-based, and observational domains and ultimately, the issue of attribution can be explored using the combined information from both approaches.

Millennium directly addresses the central objective of Sub-Priority ‘Global Change and Ecosystems’ by strengthening the scientific basis for understanding the processes and factors controlling global change and hence contributes to the protection of ecosystems and the preservation of biodiversity. Ultimately, the project will focus clearly on the most critical unresolved question concerning climate change in Europe, specifically: does the magnitude and rate of 20th Century climate change exceed the natural variability of European climate over the last millennium?
Project outputs:A list of publications by Millennium scientists is available from the project website.