Members of the TASMANDRAKE research group of the Andalusian Earth Sciences Institute (IACT), which pertains to the University of Granada and CSIC, have published a research paper in the prestigious international journal Scientific Reports describing their analysis of clays from Antarctica dating back 35.5 million years, to reconstruct past climate changes.
Glaucony grains observed under an electron microscope [Credit: University of Granada] |
The article analyses the relevance as a climatic indicator of the mineral commonly known as 'glauconite', which is more properly termed 'the glauconia facies' or 'glauconia'. This is a type of green clay, formed mainly in shallow marine environments (<500 m) with temperatures below 15° C, under very specific oxygenation conditions.
The existence of this clay formation in the Antarctic region has received little scholarly attention to date compared to other geological records on the planet. The characteristic green-coloured mineral has been observed around Antarctica and the Antarctic Ocean in sedimentary sequences of the Terminal Eocene Event—that is, before one of the main climatic transitions in Earth's history. The Eocene–Oligocene climate transition took place approximately 34–33.6 million years ago.
Northwest region of the Antarctic Peninsula (South Shetland Islands) [Credit: University of Granada] |
The formation of glauconia 35.5 million years ago marks the onset of progressive sea level rise in the north Weddell Sea during the Terminal Eocene. The results of this scientific study thus provide new insights regarding changes in paleoceanographic conditions just prior to the Eocene–Oligocene climate transition and the controversial opening and deepening of Drake Passage.
Studying the weather of the past to predict the future
The separation of the Antarctic continent from South America and Oceania allowed bodies of water to transfer freely between the Pacific and Atlantic Oceans. This new circulation of bodies of water resulted in the Circumpolar Current and, with it, the thermal insulation of the Antarctic and the formation of the ice cap on a continental scale.
To put these changes into perspective, Adrian Lopez Quiros, the principal author of the research, notes that "it is necessary to study the past to understand the present and help predict the future," by better understanding the tectonic, climatic, and paleoceanographic conditions that led to the onset and subsequent evolution of this important ocean current.
The United Nations' Intergovernmental Panel on Climate Change (IPCC), a major reference source for climate forecasts, established several possible future climate scenarios in 2014. However, the new data, when comparing simulations with real-world data, predict even greater impacts than those previously foreseen in the IPCC climate scenarios. Therefore, climate change is developing faster than previously thought. With its research, the TASMANDRAKE group aims to provide new variables for these models—focusing on sediments and geophysics—to ensure that its results reflect real-life events even more accurately, especially in terms of the transoceanic currents, global warming, and rising sea levels.
Source: University of Granada [January 23, 2020]