Can enhanced weathering provide an effective climate change mitigation strategy?

Project Rationale:

Anthropogenic inputs of carbon dioxide (CO2) to the atmosphere are the primary cause of global warming. New techniques and technologies are urgently required to reduce atmospheric CO2 levels and achieve the Paris Agreement goal of limiting the post-industrialisation increase in global temperature to 1.5°C. Enhanced Weathering (EW) is a geoengineering strategy proposed to help facilitate this by accelerating the rate of natural chemical rock weathering that regulates Earth’s atmospheric CO2 levels over long (million year) timescales [1,2]. Although EW has been tested in laboratories and on small scales, its effectiveness at sequestering significant quantities of CO2 over human timescales has yet to be determined.

This project will provide important new constraints on the effectiveness of EW for mitigating climate change. This will be done through a series of field experiments in the USA and Malaysia, where ground rocks are being applied to agricultural crops to harness the photosynthate energy of plants to accelerate their weathering rates [3]. This project will use a combination of novel stable isotope systems (e.g. Mg, Sr, Li) and other chemical techniques to characterize the rates of chemical weathering and CO2 drawdown, as well as the uptake of elements by plants and formation of secondary minerals.

Methodology:

This project will run in conjunction with the Leverhulme Centre for Climate Change Mitigation (LC3M; www.lc3m.org); a multi-institution centre dedicated to evaluating EW from field, laboratory, modeling, and societal impact perspectives. Field trials investigating EW in agricultural sites (corn/soy and oil palm) have already begun in Illinois USA, and Sabah Malaysia, respectively, and the student will have opportunities to participate in fieldwork at these locations. The stable isotopic and major chemical composition of stream, soil, and plant samples collected at these sites will be determined at the University of Southampton and used to quantify the extent of CO2 drawdown by the chemical weathering process. The student with also work with LC3M colleagues at the University of Sheffield to analyze the geochemistry of water, soil, and plant samples from experiments investigating EW under controlled laboratory conditions. The geochemical data collected from both the field and laboratory experiments will be incorporated into global models of EW being developed by LC3M collaborators.

Training:

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre. Specific training will include:

i. Practical training on sample collection (water, soil, plant material) in the field. This will occur on-site during fieldwork in Illinois, USA and Sabah Malaysia.
ii. Analysis of trace element concentrations by inductively coupled plasma mass spectrometry (ICP-MS).
iii. Training in state-of-the-art methodologies for analysis of trace metal stable isotope ratios by thermal ionization mass spectrometry (TIMS) and multi-collector ICP-MS.

In addition to exchanges associated with INSPIRE, the student will work with collaborators within LC3M on this project, both within the UK and internationally (e.g. USA, Australia).