Characterisation of MIS 11 climate versus MIS 1 in the Alps

The climate of the last 2.6 million years (Quaternary period) was characterized by alternating warm (interglacial) and cold (glacial) periods. Warm periods, such as todays Holocene interglacial, account for approximately 15% of the Quaternary period, and in the wake of current climate change, can provide useful information about how the climate may evolve in the future. The main mechanism that controls these alternating glacial-interglacial periods is the long-term change in the orbital configuration of the Earth relative to the sun, and it was a period about 425,000 years ago called Marine Isotope Stage (MIS) 11, that best resembles the orbital conditions of today. Unfortunately, several glacial-interglacial cycles have taken place since then, and a large part of the evidence archived in the geological record has been removed. Where records do exist, there are fundamental gaps in our knowledge related to: the timing of events; the duration of the warm period; the stability of the climate; whether or not this period was warmer and wetter than today, and; how the vegetation responded. This proposal seeks to address these issues using stalagmites deposited in caves in the northern Alps that have been protected from physical and chemical erosion. Preliminary work has shown that many stalagmites exist which are suitable for a study into MIS 11 climate variability. Development of the climate archive will use several well-established techniques, in addition to a couple of new innovative methods. Stalagmites have an enormous advantage over other climate archives because they can be independently dated, accurately and precisely, using the radioactive decay of uranium and thorium. Dating work will be undertaken in collaboration with world-leading experts using state-of-the-art facilities at the University of Minnesota. Climate variability and vegetation dynamics will be detected by analysis of the stable isotopes oxygen and carbon, plus trace elements magnesium, strontium, barium and phosphorous, in addition to fluorescence intensity. We will also explore the possibility of obtaining quantitative constraints on temperature using two new innovative methods: fluid-inclusion analysis and 47 clumped isotope analysis. The research will be undertaken using both in-house facilities at the University of Innsbruck, and also in collaboration with experts in the UK and Germany. The results obtained from this research will be compared with the evolution of the climate during the Holocene interglacial thus far. Working in collaboration with modeling experts at the University of Bristol, we intend to integrate the data into climate models to test hypotheses of past climate change, and make more informed statements of future change.

Approximately 400,000 years ago, during a period known as marine isotope stage 11 (MIS 11), the Earths orbital configuration relative to the sun was similar to that of today. Because of this similarity, MIS 11 provides an important baseline for the natural conditions that would be expected today. Unfortunately, because of its old age, much of the evidence for how it developed has been erased from the geological record. Using geochemical signatures trapped within stalagmites from caves in the northern Alps, this project has been successful in constructing a high-resolution, precisely dated record of climate change for this important time period. In particular, this project has been able to date climatic events of this age to a very high-precision i.e., ages are quoted at plus or minus 800 years, rather than the previous 2,000 years. Such high-precision is a major advance for palaeoclimate research as it enables meaningful interpretation of climate change. Furthermore, when comparing the new record produced in this study to records of Asian monsoon strength or Antarctic temperatures, it is possible to establish periods of coupling and de-coupling between the different regions, which provides important insights into atmospheric and ocean circulation patterns.