Isotope-enabled climate modelling to better understand long-term rainfall dynamics in North Africa
Dr P Hopcroft
Dr M Widmann
Dr G C LECKEBUSCH
Applications accepted all year round
Self-Funded PhD Students Only
• Study climate in a region that is particularly vulnerable to future change
• Use isotope-enabled and high-resolution climate model simulations to investigate how the Sahara became ‘Green’ 9000-4000 years ago
• Address long-standing model errors in this region
During early to mid-Holocene from around 9000-4000 years ago, the Sahara was transformed by vegetation growth and the development of now absent waterways and lakes. Pollen and macro-fossil evidence suggests that annual mean rainfall increased by around 400 mm/year in the Sahara, evidence for a strong response to the gradual change in Earth’s orbit around the Sun. However, general circulation model (GCM) simulations generally fail to match this . Major questions remain about how this humid period occurred and why climate models used for future projections cannot reproduce this event in the past .
In this project you will benefit from recent findings at the University of Birmingham on understanding the ‘Green’ Sahara. You will perform new snapshot simulations including water isotopes in the atmosphere and ocean and carbon isotopes in vegetation to better compare the climate model simulations with isotope ratios measured in geological samples and marine cores from this time period. These simulations will be the first of their kind and will have the potential to transform our understanding of many of the geological and marine core archives relating to this time period, refining estimates of the climatic changes that occurred.
You will also use a very high resolution model version to understand the interaction between westerlies and regional synoptic features  and their influence on rainfall and the distribution of isotopes. Recent work suggests that higher resolution is a key step to understanding rainfall regimes in the region .
This work will address questions about how realistic is simulated rainfall in climate models, how do isotopes measured in archives relate to physical climate, and are climate models overly stable ?
In this project the student will learn to use the UK Met Office’s climate model and will benefit from the University of Birmingham’s Environment for Academic Research (BEAR) high-performance computing facility.
Candidates should hold a degree in physical or mathematical science discipline and ideally have some experience of computer programming or modelling.
For further details on this project please contact Dr Peter Hopcroft ([Email Address Removed]). Applications can be submitted at any time via the University of Birmingham website.
Self funded students
1] Harrison, S. et al. (2015). Nature Climate Change 5, 735–743.
 Hopcroft, P. et al (2017), Geophysical Research Letters 44, 6804-6813.
 Skinner, C. & C. Poulsen (2016). Geophysical Research Letters 43, 349–358.
 Vellinga, M. et al (2016), Geophysical Research Letters, 43, 326–333.
 Valdes, P. (2011). Nature Geoscience 4, 414–416.
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FTE Category A staff submitted: 25.00
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