Palaeolimnological assessment of methane emissions from lakes in changing environment using stable isotopes

ended

This proposal (PALAEO) aims to provide completely novel insights into the long-term dynamics of methane (CH4) concentrations and emissions from lakes in response to past climatic variation and anthropogenic impact. Lakes are an important component in the global carbon budget and their role as major sources of greenhouse gases, particularly CH4, has long been underestimated. This is partly due to the absence of long-term data sets of CH4 emissions from lakes, which makes predictions and modelling of lake ecosystem responses to future climate change extremely difficult. PALAEO will combine a unique experimental system, contemporary field observations and state-of-the-art palaeolimnology to develop, validate and apply methods to track long-term dynamics in CH4 in lakes. The different spatial and temporal scales are linked by a consistent methodology using stable isotope analysis applied to chitinous invertebrate remains, which have the potential to reflect past CH4 concentrations in the water. Sediment cores from the Arctic (Greenland), boreal (Finland) and temperate (Denmark) regions will be analysed. These cores also provide information on past environmental and ecological conditions, such as temperature, nutrient levels and community structure. Sampling from regions that have shown large climate variations (Arctic, boreal) and highly variable degree of human impact (boreal, temperate) will provide unique data for modelling how CH4 emissions from lakes will be affected under future warming scenarios. In addition, these data will allow the assessment of the relative importance of multiple pressures (climate warming, eutrophication) in driving the increases of CH4 emissions from lakes in different regions. This makes PALAEO a highly novel study linking change in the environment and ecosystem structure to long-term change in a key ecosystem process with global significance – CH4 production and emission.