Identifying orbital- and sub-orbital-scale controls on the Asian summer monsoon: a 500,000 year hydroclimate record from Nam Co, Tibet [NamCore-UK]
Lead Research Organisation:
Manchester Metropolitan University
Department Name: School of Science and the Environment
Abstract
The Tibetan Plateau, located north of the Himalaya mountain range, is a large geographical area with an elevation greater than 4 km above sea-level. It is called "The Third Pole" because it has the third highest glacier ice volume after the Arctic and Antarctic, and it is a region that is already experiencing the effects on the ongoing global climate crisis. The Tibetan Plateau and associated glacier ice also have great significance for many neighbouring Asian countries, being the source of many of the major river systems supplying water to 100s of millions of people, as well as sediment that builds several mega-deltas that are homes to 10s of millions of individuals. The Tibetan Plateau also plays a major role in the Indian summer monsoon atmospheric circulation system, with the Sun's heating of the high-altitude region traditionally thought to set up a low-pressure cell (i.e., upward flowing heated air), into which wetter air masses are drawn from the Indian Ocean, from which seasonal monsoonal rain then falls over the Indian sub-continent. However, there remains a lack of detailed understanding of the controls on, and the complexity of, Asian monsoon systems, and additional knowledge is required in relation to how climate in this region will develop under future climate-change scenarios that will result from ongoing global warming.
One way to gain an improved understanding of natural Earth systems, such as the Indian summer monsoon, is to investigate such systems in the historical and geological past, i.e. by the reconstruction of past climate (called palaeoclimate), one commonly used statement being "the past is the key to the present". To be able to investigate palaeoclimate it is necessary to have an archive of information and a means to reconstruct key palaeoclimate parameters, the latter termed a proxy-based approach because one measures something preserved in the archive (the proxy) that exhibits a relationship with the key parameter of interest. Continental lake sediments are one important archive and this project will utilise such materials from lake Nam Co on the Tibetan Plateau. Prior investigations of this lake have shown there is around 700 metres of sediment buried below the lake floor and it is expected that these sediments extend back to around one million years before present. The significant international value of the Nam Co lake sediment archive was recognised in summer 2020 by panels of international researchers who awarded US$1.5M from the International Continental Drilling Project (ICDP), an international agency currently with 21 member countries (including the UK). An additional US$0.9M funding also has already been committed by the Institute of Tibetan Plateau Research, Chinese Academy of Science (Beijing, China), further confirming the significance of this large-scale international research project.
The Nam Co sediment archive will be recovered during summer 2023 by coring from a drilling rig sitting on top a barge that will float on the lake surface, an approach that has been applied successfully to many other ICDP lake drilling projects. Once the lake sediments have been recovered from below the lake floor they will be subject to numerous biological, chemical and physical measurements, in order to address the fundamental science questions that the Nam Co sediment archive will allow to be addressed. This UK NERC-funded project, including two of the proponents of the main ICDP project, will: 1) contribute additional funding to the lake coring operations; 2) apply chemistry-based dating techniques, so that the ages of the recovered sediments can be determined; 3) complete chemical proxy measurements on the lake sediments for palaeoclimate reconstruction, specifically with a focus on improving understanding of the water balance on the Tibetan Plateau and how that relates to controls on the Indian summer monsoon.
One way to gain an improved understanding of natural Earth systems, such as the Indian summer monsoon, is to investigate such systems in the historical and geological past, i.e. by the reconstruction of past climate (called palaeoclimate), one commonly used statement being "the past is the key to the present". To be able to investigate palaeoclimate it is necessary to have an archive of information and a means to reconstruct key palaeoclimate parameters, the latter termed a proxy-based approach because one measures something preserved in the archive (the proxy) that exhibits a relationship with the key parameter of interest. Continental lake sediments are one important archive and this project will utilise such materials from lake Nam Co on the Tibetan Plateau. Prior investigations of this lake have shown there is around 700 metres of sediment buried below the lake floor and it is expected that these sediments extend back to around one million years before present. The significant international value of the Nam Co lake sediment archive was recognised in summer 2020 by panels of international researchers who awarded US$1.5M from the International Continental Drilling Project (ICDP), an international agency currently with 21 member countries (including the UK). An additional US$0.9M funding also has already been committed by the Institute of Tibetan Plateau Research, Chinese Academy of Science (Beijing, China), further confirming the significance of this large-scale international research project.
The Nam Co sediment archive will be recovered during summer 2023 by coring from a drilling rig sitting on top a barge that will float on the lake surface, an approach that has been applied successfully to many other ICDP lake drilling projects. Once the lake sediments have been recovered from below the lake floor they will be subject to numerous biological, chemical and physical measurements, in order to address the fundamental science questions that the Nam Co sediment archive will allow to be addressed. This UK NERC-funded project, including two of the proponents of the main ICDP project, will: 1) contribute additional funding to the lake coring operations; 2) apply chemistry-based dating techniques, so that the ages of the recovered sediments can be determined; 3) complete chemical proxy measurements on the lake sediments for palaeoclimate reconstruction, specifically with a focus on improving understanding of the water balance on the Tibetan Plateau and how that relates to controls on the Indian summer monsoon.
