Europe's palaeoclimatic changes
The NAO is a variable weather phenomenon having no particular period. The cycle strongly affects Europe's climate, and therefore Europe's culture and economy as well. Funded by the EU, the NAOSIPUK (Natural responses to past North Atlantic Oscillations: Southern Iberian peninsula vs. United Kingdom. Analogues for future environmental changes) project investigated the Oscillation's history to help predict its future. The team compared sites in Spain and the United Kingdom, using various geochemical, geophysical and sedimentary indicators of previous climates. The sites were chosen because they show an opposite response to the normal European NAO-caused climatic changes. The team analysed five Holocene or late Pleistocene sedimentary records from southern Spain and three from the United Kingdom. Researchers analysed the sediments' organic composition, and sediment-specific biomarkers. The results detailed the source of organic matter, temperature ranges and hydrological changes. Findings showed that palaeoenvironmental indices derived from biomarkers agreed with conclusions derived from isotopic data taken from Spanish bogs. As expected, the trends at the two sites were opposite European averages, helping the team separate local from regional effects. Researchers concluded that during the late Holocene, solar forces and NAO fluctuations mainly drove environmental evolution. The team identified abrupt changes during the recent century. Comparison between Spanish and United Kingdom sites showed a stable middle Holocene at high latitudes. However, the Spanish data revealed abrupt changes during the period 7 000 to 5 000 years ago. The team suggested that the NAO either began or increased its influence during the period. The NAOSIPUK project's climate model helped reveal the interconnection between southern and northern European climatic zones. By determining the forces affecting prehistoric climate change, researchers will be better equipped to predict future change.
Keywords
North Atlantic Oscillation, climate, NAOSIPUK, sediment, environmental evolution
