A high-resolution record of Holocene Monsoon intensity from Central Asia
Lead Research Organisation:
Imperial College London
Department Name: Earth Science and Engineering
Abstract
The Asian monsoon system is an important component of the climate system. Moreover, it exerts a major impact on the regional population, due to associated strong summer rainfall. In a world of changing climate, the Asian monsoon system is one of the major systems we must gain a better understanding on to accurately predict the future. A powerful way to increase our mechanistic understanding of the climate system is to look into the past. For example, chemical analyses of cave deposits constitute an effective way to learn about the history of rainfall in Asia. From such records we know that the intensity of the East Asian summer monsoon gradually weakened over the last ~9000 years. A similar evolution has been documented for the Indian summer monsoon. When comparing both monsoon histories with changes in the orbit of the Earth around the sun, so called orbital forcing, a general linkage can be found, suggesting that changes in the Asian monsoon system may also be linked to changes in other parts of the climate system (i.e., oceans, ice sheets). However, when looking in more detail, this neat correlation seems to fall apart: proxy records for precipitation from various lakes in Central Asia indicate an out-of-phase relationship of the two Asian summer monsoon systems and a high degree of variability throught the time interval of our current 'stable' interglacial, the Holocene (i.e., last 10,000 years). One way to explain this apparent controversy is to not only think about the actual amount of rainfall recorded, but to also think about where this rain was originating from. The Indian Summer monsoon is associated with southwesterly winds, while the East Asian summer monsoon is associated with southeasterly winds. Such different source regions could play an important role when trying to understand the monsoon records of the past. Hence a prime target for ongoing climate research is to find a way to reconstruct directions of winds in the past. In this project we will reconstruct such wind directions by analysing the dust extracted from a 9,600 year old core from a peat bog from the Eastern Qinghai-Tibetan Plateau. The continuous peat material contains inorganic dust, and this dust in turn carries a chemical fingerprint from the area where it was picked up. If we reconstruct this dust fingerprint for the last 9,600 years, we can infer a detailed history of wind directions and strengths in central Asia, allowing us to identify the prevailing monsoon sub-system at any given time. The result will be a local monsoon record, which can then be compared to other regional and global climate records. Agreement (or disagreement) between record is what tells us about common driving forces (or decouplings) in the climate system. It is this information which is vital for feeding climate models to accurately reconstruct the past and ultimately to predict the future. We work in close collaboration with modellers in Hamburg, who have developed a regional climate model for China and who look forward to including our new data. Previous collaboration with Hamburg already developed the dust code for the model to be used. Specific outcomes of the project will be: (1) the first ever high-resolution record of changes in the atmospheric circulation systems and of the weakening and strengthening of the East Asian and Indian Monsoon systems over Tibet during last 10,000 years, (2) the first record of any movement of the present day boundary between the two subsystems, and (3) contributing to the development of a regional climate model for China to predict future climate change.
Publications
De Vleeschouwer F
(2020)
Comment on: "A novel approach to peatlands as archives of total cumulative spatial pollution loads from atmospheric deposition of airborne elements complementary to EMEP data: Priority pollutants (Pb, Cd, Hg)" by Ewa Miszczak, Sebastian Stefaniak, Adam Michczynski, Eiliv Steinnes and Irena Twardowska.
in The Science of the total environment
Ferrat M
(2012)
The inorganic geochemistry of a peat deposit on the eastern Qinghai-Tibetan Plateau and insights into changing atmospheric circulation in central Asia during the Holocene
in Geochimica et Cosmochimica Acta
Ferrat M
(2012)
Lead atmospheric deposition rates and isotopic trends in Asian dust during the last 9.5kyr recorded in an ombrotrophic peat bog on the eastern Qinghai-Tibetan Plateau
in Geochimica et Cosmochimica Acta
Ferrat M
(2011)
Improved provenance tracing of Asian dust sources using rare earth elements and selected trace elements for palaeomonsoon studies on the eastern Tibetan Plateau
in Geochimica et Cosmochimica Acta
Gallagher K
(2011)
Inference of abrupt changes in noisy geochemical records using transdimensional changepoint models
in Earth and Planetary Science Letters
Izquierdo M
(2015)
Measurement of isotopically-exchangeable Zn in Zn -deficient paddy soil
in European Journal of Soil Science
Description | Key discoveries are (i) we find no evidence of signifiant impact of the Indian monsoon over Central Asia since the last glaciation. (ii) we confirm that peat records record truthfully long range transport of dust in Central Asia (iii) we determine periods of changing intensity of the westerly jet over Central Asia. this has direct implications on the presence of teleconnection between North Atlantic and (iv) we determine for the first time the periods when the East Asian and the Summer Monsoon were active during the Holocene |
Exploitation Route | The change point modeling developed during this project is now widely used in the community studying mineral dust deposition The peat archive is now widely used in the paleo climate community to study the dynamics of past atmospheric dust fluxes and circulation |
Sectors | Environment |
Description | The work has led to the development of a computer program that enables the determination of change points in dust records from geological archives (program has been written by Prof Gallagher at the University of Rennes, and is maintained at the following web page (https://geosciences.univ-rennes1.fr/spip.php?rubrique332?=fr) We also used the work to start collaborations with the South Atlantic Environmental Research Institute under the direction of Dr Bickle and we were invited to write an article in the general science journal PAGES |
First Year Of Impact | 2013 |
Sector | Digital/Communication/Information Technologies (including Software),Environment |
Impact Types | Cultural |
Description | CLIM AMAZON |
Amount | £90,000 (GBP) |
Funding ID | 295091 |
Organisation | European Research Council (ERC) |
Sector | Public |
Country | Belgium |
Start | 11/2012 |
End | 10/2015 |
Description | Ocean micronutrient cycles: UK GEOTRACES |
Amount | £259,027 (GBP) |
Funding ID | NE/H005390/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 08/2010 |
End | 09/2014 |
Description | Revisiting the Neodymium Paradox |
Amount | £365,608 (GBP) |
Funding ID | NE/J021636/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 08/2012 |
End | 03/2017 |
Description | SOUTHERNCHANGE |
Amount | £180,000 (GBP) |
Funding ID | 702916 |
Organisation | European Research Council (ERC) |
Sector | Public |
Country | Belgium |
Start | 09/2016 |
End | 09/2018 |
Description | University of Hamburg |
Organisation | University of Hamburg |
Country | Germany |
Sector | Academic/University |
PI Contribution | experimental record of dust deposition |
Collaborator Contribution | calibration of the REMOTE model |
Impact | REMOTE model calibrated for Central Asia |
Description | University of Rennes |
Organisation | University of Rennes 1 |
Country | France |
Sector | Academic/University |
PI Contribution | dust deposition data set from peat archive |
Collaborator Contribution | CPM |
Impact | Change point model |
Title | Basin Change point Model |
Description | application for change point modeling in geological data sets |
Type Of Technology | Software |
Year Produced | 2011 |
Open Source License? | Yes |
Impact | change point modeling is now widely used in the peat archive community |
URL | http://www.iearth.org.au/codes/ |
Description | Outreach talk at the Environmental Society of the Falkland Islands |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Schools |
Results and Impact | Eleonore gave a talk on peat bogs and how they are used as archives of atmospheric metal deposition to the local environmental society, which was joint by the local school |
Year(s) Of Engagement Activity | 2019 |
Description | Public Talk at the Natural History Museum |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Gave a talk at the Nature Talk series of the Natural History Museum |
Year(s) Of Engagement Activity | 2011 |