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Climate change in Southeast Asia: Researching the impacts on rainfall and drought

Climate|Medioambiental
Climate and Resilience Hub|Climate Risk and Resilience

By Nalan Senol Cabi and Geoffrey Saville | September 24, 2021

Climate change has been high on the global agenda for some time now. Re/Insurance and finance industries are in the centre of the conversations on sustainability and resilience.

Climate change has been high on the global agenda for some time now. Re/Insurance and finance industries are in the centre of the conversations on charting a sustainable and resilient course for the future. It has global impact, but the latest projections confirm that the direction and the extent of the impact is not equally distributed. When it comes to understanding and quantifying the “change” and the complex processes behind it, regional climatology plays an important role.

As a proud contributor to the climate change discussions, Willis Towers Watson has been working with National University of Singapore (NUS) Tropical Marine Science Institute (TMSI) since the devastating floods in Jakarta, Indonesia in 2007. As one of the earliest academic members of the Willis Research Network (WRN), TMSI has significant experience in developing hydrological and hydraulic models for evaluating flood risk in Southeast Asia. TMSI specializes in climate research with extensive experience, particularly, in high-resolution dynamical downscaling of global climate models to a range of more granular spatial scales – from regional (10-20 km) to local (urban) (400 m – 2 km).

Over the years collaborating with NUS, Willis Towers Watson developed risk models for the region and are deriving real benefits in helping clients understand and manage their financial exposures. Investigating influences of climate change on extreme flood events became the focus of our applied research collaboration. For this quest, and to better quantify the future climate impact on rainfall, NUS analysed the projected precipitation and temperature changes in Southeast Asia.

The precipitation data were created from a dynamical downscaling study of three general circulation models (GCMs); ACCESS, ECHAM and MIROC, and using a Numerical Weather Prediction (NWP) model called the Weather Research and Forecasting (WRF) model, to enhance resolution from global to regional scales. The WRF is run at a regional scale and can capture dynamical physical processes which the global scale GCMs do not. By running the WRF model at three main time horizons: present-day, near-term future (2021-2040) and long-term future (2081-2100), and under two emission scenarios; Representative Concentration Pathway (RCP) 4.5 and 8.5; the delta changes (%) of precipitation and temperature variables were calculated.

The research outputs of this study provided insight for the projected change in precipitation and drought distributions in Southeast Asia domain, with a detailed representation of the spatial variations across the region. By using the same original source of climate inputs across a region that can drive new hazard representations of both hydrological extremes – flood and drought, that have comparability across time horizons and at the same spatial resolutions – the research outputs created by NUS enable better risk representations that explicitly reflect the interconnectedness of the extremes.

Potential applications of such insight can include climate conditioning of a global scale flood risk model, developing realistic scenarios for portfolio sensitivity analysis, and/or adjusting hazard event sets in catastrophe models in SE Asia. By utilizing a multi-disciplinary combination of climate science and flood risk expertise, TMSI and WRN are exploring the flood risk in Southeast Asia now and the future.

National University of Singapore

The Tropical Marine Science Institute (TMSI) in NUS is a centre of excellence for research, development and consultancy in tropical marine science as well as environmental science. With its multi-disciplinary research laboratories and active international links, it handles projects relevant to Marine Biology, Marine Mammals, Climate Change, Water Resources, Shallow-water acoustics; Underwater technologies and Physical Oceanography. Through active collaboration with academic, government and industrial sectors, TMSI plays a strong role in promoting integrated marine science, in R&D, and as well as to establish itself as a regional and international education and training centre.

Ecological Monitoring, Informatics and Dynamics (EMID) Research Group, TMSI.

Authors

Head of Flood Risks Research


Head of Weather and Climate Risks Research

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