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Monsoons of Asia caused Greenhouse to Icehouse Cooling

Periodic Reporting for period 3 - MAGIC (Monsoons of Asia caused Greenhouse to Icehouse Cooling)

Reporting period: 2018-09-01 to 2020-02-29

What is the problem/issue being addressed?
Unraveling the cause for Cenozoic global climate cooling is one of the most important unresolved questions challenging the Earth and Environmental sciences community today. Increased erosion and weathering of the uplifted Tibetan Plateau and Himalayas, is advocated as the primary cause for the enigmatic pCO2 drawdown, that led to global cooling 50 to 34 Myrs ago from the warm ice-free Greenhouse world to the bi-polar Icehouse conditions still prevailing today. Asian Monsoons are genetically linked to high orography associated with the India-Asia collision starting ca. 50 Myrs ago, however, the relation between Greenhouse to Icehouse cooling and Asian Monsoons remains to be explore as they were previously thought to intensify only much later ca. 25 Myrs ago.

What are the overall objectives ?
Our recent findings of monsoonal activity in Asia since at least 45 Myrs ago raises the fascinating possibility that Asian Monsoons may have triggered global cooling from Greenhouse to Icehouse conditions. Testing this novel hypothesis and exploring its implications on feedback mechanisms between regional environments, Asian Monsoons and global climate, will constitute the stimulating objectives of MAGIC.

Why is it important for society?
Asian monsoons govern the life of billions of people. In the past they have been the driver of major paleoenvironmental changes and biotic evolution shaping the Asian landscape as it is today. In this project we aim to understand the mechanisms that are and have been controlling monsoons since their onset over 50 millions years ago. Monsoons may be enhanced or reduced by a wide range factors including mountain uplift, pCO2 level, vegetation and land sea distribution. We will explore if pCO2 levels and global temperatures may have increased monsoons in greenhouse times as they do today as well as in the future. Ultimately, we will explore how monsoons can change global climate through regional to global feedback mechanisms between regional denudation, weathering and erosion of uplifting material and global pCO2 levels.
It has appeared clearly during our recent mid-term MAGIC meeting that we have reached the scientific objectives set up in the Description of Action (DoA). The project is going according to plan with exciting discoveries and developments.

The DoA has been set up as 3 main objectives overlapping in time:
Objective A. Three PhDs date and describe each sedimentary environmental record from NE Tibet (China), SE Asia (Myanmar) and the Paratethys region (Western China and Tajikistan) respectively.
Objective B. Postdocs apply and develop various environmental proxies to these sedimentary records with the goal to characterise environmental changes (climate-Tectonics and Paleogeography).
Objective C. An integrative climate modeler integrates dated proxy records to constrain simulations.

Objective A on stratigraphy is completed. We have been able to access, sample and date the three targeted records.
Objective B on proxies is ongoing. Some objectives have been already achieved and ongoing work includes exciting cross-calibration of multi-proxy tools being developed within MAGIC.
Objective C on climate modeling is just starting. Promising pilot results have been obtained already with simulations based on the paleogeographies developed earlier within MAGIC.

This Earth and Environmental project is interdisciplinary by concept and design. The project gathers 3 main partner institutions (CNRS, Potsdam University and University of Amsterdam) and joins scientists from these and other institutes in various disciplines. It integrates sedimentology, geochimestry, paleobiology, tectonics and climate modelling. In particular we are bridging tectonics and paleoclimate by building paleo-bio-geographies and environmental constraints that are used as the basis for climate, geodynamic and biological models.
Several methodologies used in this project are novel or being developed. In particular, sediment provenance methods as well as clumped isotopes and leaf waxes analyses are applied here for the first time on 50 to 40 Ma windblown loess deposits with important implications on the development of Asian monsoons.
Several activities have contributed to a real team building amongst the members of the project despite being located in 3 different sites (CNRS, France, Potsdam University and Amsterdam University). Fieldwork has been a central part of this project uniting its various members and their respective expertise. It is the best place to build tight relationships and provides time and experience that forge scientific ideas and project goals. With three field seasons per year a good knowledge of the respective research focus has been obtained with sharing of knowledge between the participants. In addition, regular workshops have taken place every few months at the various institutions to set various goals and enabled to share ideas and data, work on publications and resolve administrative tasks. Finally, the participation at international meetings presenting respective results has started to establish the MAGIC team as a major player in the field.
Most of the climate and environmental proxies are currently being analysed. In particular fossil pollen records from the three target areas are yielding promising results that will form an extensive and well-dated reference database. In conjunction, a new Potsdoc appointed in February is currently building a record of fossil leaf wax and their isotopic signatures indicating plant types and environmental conditions with promising preliminary results. This novel technique partially developed in Potsdam enables to determine, plant types, temperatures and precipitations and ultimately evapotranspiration of the plant can be further determined when combined with other proxies. A highlight of this project is the contribution to the development by a postdoc in the project of a novel approach that enables to derive chemical characteristics from the fossil pollen walls. The technique is yielding promising results enabling to interpret species as well as environmental variations and in particular paleo-elevations. It is now being applied by several members of our group to the targeted records. With these new paleo-environmental proxies, the project is currently crossing from Geology towards Biology with the help of the close collaboration in the project of the Pollen group of the University of Amsterdam, climate-vegetation modelers and biologists.
But most of the expected results until the end of the project will come from climate modeling integrating the dated proxy records as originally planned. Two PhDs have been recently hired in the frame of MAGIC. Pilot results have been obtained already because we had already planned in advance the simulations based on the paleo-geographies developed earlier within MAGIC at Rennes University. The integration of the data into the models is very effective due to the overlap of the projects and the numerous meetings and fieldworks including all the members. Further modelling goals are to be achieved, especially integrating the database to compare to the paleo-bio-geography evolution, the influence of long- and short-term global changes on Asian environments and the contribution of monsoonal weathering to the global carbon cycle.

An unexpected progress beyond the state of the art is the development of an interactive paleo-geodatabase webtool. This tool is being put together for release in 2018 for the broader scientific and educational community with interest in Earth and Environmental sciences. Paleomaps reconstructed by our MAGIC team will be available along with the geological database produced in this project but also integrating other global geological databases, outputs of climate and vegetation models. Individual participant portraits in short videos are currently being put together for release in 2018 along with a longer film of the project overview destined to the general and scientific audiences.
The use and building of this web tools along with the MAGIC website with the presentation of the team members actively contributes to the MAGIC team identification and establishment.
MAGIC team building