The Harper Lab @UGA

I’m very happy to say that Tim Lam recently passed his viva at the University of Exeter. His dissertation title was “Causal pathways of teleconnections to drought and peatland fires in Indonesian Borneo.” I served on Tim’s PhD committee while at the University of Exeter, and have continued to support him since moving to UGA. His main supervisor was Dr. Jennifer Catto.

Tim’s research focused on using causal networks to understand drivers of drought and fire risk. Part of his work was also recently published in the International Journal of Climatology: Quantifying causal teleconnections to drought and fire risks in Indonesian Borneo¹. In that study, Tim quantified the strength of teleconnections to droughts at a seasonal timescale in observations and climate models. Droughts in Indonesian Borneo can be associated with devastating fires, such as occurred during the 2015-2016 El Nino. Tim found that droughts can be predicted with a lead time of 3 months based on their associations with Pacific sea surface temperatures (SSTs), with higher SSTs preceding drier conditions. Under an extreme climate change scenario (SSP585), the CMIP6 multi-model ensemble shows a significant increase in both the maximum number of consecutive dry days in June-August and its linear association with Pacific SSTs in March-May (in 2061 to 2100 compared to the historical baseline).

Tim also used an emerging method for quantifying risks of extremes using large ensembles. This method (called the Unprecedented Simulated Extremes using Ensembles method, or UNSEEN²) assumes that the observed record is just one possible realization of outcomes within the climate system, due to the substantial internal variability in Earth’s climate. Climate models are used to produce large ensembles of the recent past, greatly increasing the sample size of extreme events and enabling a more robust analysis of their likelihood and properties. Using this method, Tim found that an El Niño raises the chance of an unprecedented fire season at present day by a factor of around 2.7, yet a major event is possible under all ENSO phases.

Tim now holds a postdoctoral research position at PIK in Potsdam, Germany.

1. Lam, T., Catto, J. L., Barciela, R., Harper, A. B., Challenor, P., & Arribas, A. (2024). Quantifying causal teleconnections to drought and fire risks in Indonesian Borneo. International Journal of Climatology, 1–19. https://doi.org/10.1002/joc.8442 ↩︎
2. Thompson, V., Dunstone, N.J., Scaife, A.A. et al. High risk of unprecedented UK rainfall in the current climate. Nat Commun 8, 107 (2017). https://doi.org/10.1038/s41467-017-00275-3 ↩︎