Testing novel isotope approaches to reconstruct past precipitation regimes in the Amazon

Abstract

The South American summer monsoon brings vast amounts of precipitation to the Amazon basin, providing an important lifeline to its forest and livelihoods. However, it remains uncertain how climate change and increasing C02 levels will affect Amazonian precipitation. In this proposal we attempt to gain insight in the Amazon hydrological cycle by reconstructing its climate responses in the past using isotopes in precipitation. The aim of this proposal is to build a new partnership between UK and Brazilian scientists working on two important natural proxies; isotopes in tree rings and speleothems (cave formation, stalactite, stalagmite). Specifically, we will I) test new - but yet unproven - methods to separate isotope variation in tree rings due to leaf evaporation, from the precipitation isotope signal and II) organize a workshop to assemble a network of scientists working on paleoclimate changes over Amazon and adjacent regions, with the aim to improve and spatially integrate Amazon climate reconstructions with the aim to gain more understanding also of future possible responses. The activities will involve new data collections in Brazil (Minas Gerais and the Amazon basin) and subsequent isotope analysis, exchange visits between researchers of Sao Paulo and the UK, and the organization of an international workshop in Sao Paulo which will bring together scientists from Brazil, UK, USA, Bolivia, Argentina, Peru, and Colombia. If successful, the proposed pilot project will open the possibility to reconstruct more faithfully past precipitation records of the 10 Amazon but also and equally importantly to reconstruct tree physiological responses to a warming and increasingly high C02 world. These are important topics, which are ideal for future collaborative efforts and grant applications. (AU)