Friday, 12 December 2014

Life in our ancient oceans... by Sonja Felder

Sonja is just starting out on a journey, travelling back through millions of years of Earth's history, to understand what impacts past climate changes had on the delicate life in our oceans...
Hi, I’m Sonja and I recently took up a PhD project (through IAPETUS, a Doctoral Training Partnership between the Newcastle University and BGS). My research is aimed at investigating past climate changes and the impact on marine life through millions of years of Earth’s history…Specifically I will be analysing cores of marine sediments which were collected from the Sea of Japan by the Integrated Ocean Drilling Program (IODP), a major international scientific ocean drilling programme. Some samples have already arrived in Newcastle and I have begun to look at the numbers and types of tiny fossils that occur in the sediments.

You probably know that in Earth’s history there have been times of colder and warmer climate. We call the really cold periods “glacials” (large ice caps on the Poles) and the really warm periods “interglacials” (small or no ice caps on the Poles). Currently, as we enjoy warm summers (well, not necessarily in the UK!) we live in an “interglacial” period (the ice caps are relatively small). The changes between glacial and interglacial periods have been cyclical. These natural climate changes happen due to variations in the astronomical parameters, such as how close the earth is to the sun during summer (precession) or how strongly the earth is tilted towards the sun (obliquity). These astronomical settings are also called “orbital parameters” as they refer to the earth’s orbit, its position in the universe. About one million years ago there was a major reorganisation in the timing of the cyclicity from 41,000 year cycles to 100,000 year cycles. This period is the so called Mid-Pleistocene Transition (MPT). What caused the MPT is one question I will be trying to tackle!

Back to my PhD site. I will be working on sediments collected from the Sea of Japan. This area is nowadays strongly influenced by the monsoon over Asia (the greater the monsoon the greater the amount of freshwater into the Sea which vary between glacial and interglacial periods), so I will need to think about both the effects of changes in the oceans and on the continents. To investigate these two systems I will use various methods, one of them is to measure the chemistry of foraminifera. These are tiny planktonic organisms which produce shells of the mineral calcite. The chemistry is dependent on parameters such as temperature or salinity of the ocean water. When the foraminifera die, the shells sink to the ocean floor and accumulate in the sediment in a time ordered way (i.e. oldest at the bottom of the sediment core).

 So far for now, I will be back to you with news on my project in a couple of months after having generated some (hopefully) super awesome data!

Newcastle University and the British Geological Survey, supervised by Dr Andy Henderson and Prof Melanie Leng

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