Changes in tropical weather patterns are causing more frequent extreme weather events, such as heatwaves and heavy rainfall, in the Indo-Pacific region, an international study led by researchers from CDE has found.
The research, led by PhD student Chenyu Dong and Assistant Professor Gianmarco Mengaldo (Mechanical Engineering), used a new approach to examine daily weather patterns over time. This approach, rooted in dynamical systems theory — a branch of mathematics that studies how complex systems change over time — allowed the team to uncover occurrence trends of weather patterns that were not visible in previous studies, helping them link these patterns to an increase in extreme weather events.
“Our study is one of the first to disentangle trend versus variability in the tropics, an aspect that has been historically challenging," said Assistant Professor Mengaldo. “We show that the changes identified cannot be fully explained by interannual modes of variability, and a possible culprit is anthropogenic global warming, though the influence of other factors, such as aerosols, may play a role.”
The team’s findings were published recently in the journal Nature Geoscience.
Key findings
Dynamical systems theory is used to help explore and understand how systems like the atmosphere evolve, revealing patterns or recurring behaviours. By applying this method, the researchers found that since the 1990s, new large-scale weather patterns have emerged, while others that were once common have nearly disappeared.
These new patterns are connected to changes in the Pacific Walker Circulation, a major system that influences tropical weather.
Using this new analysis to detect changes in daily weather patterns, the researchers were able to link these emerging patterns directly to extreme weather events. In some areas, heatwaves have become up to four times more frequent, while other regions have seen a marked increase in heavy rainfall.
"In countries like Singapore and Indonesia, heatwaves are becoming more common," Asst Prof Mengaldo said. "Meanwhile, we see that places such as the South China Sea and Vietnam are experiencing more frequent intense rainfall."
How the research was conducted
As well as researchers from CDE, the study involved an international team of climate scientists from leading institutions, including Institut Pierre-Simon Laplace (IPSL), Uppsala University, Stockholm University, University of Cambridge, Columbia University, the World Meteorological Organization (WMO), and the Centre for Climate Research Singapore (CCRS).
Rather than focusing on weather averages over long periods, the team studied how individual weather patterns recur and change from day to day, giving them a more detailed understanding of how these patterns are connected to extreme weather events.
The researchers say their novel approach helped them to pick up on changes that other methods missed, revealing how specific weather patterns are becoming more common and are contributing to extreme events like heatwaves and heavy rainfall.
Impacts on the region
The Indo-Pacific is home to over a billion people and includes countries that are highly vulnerable to extreme weather with heatwaves and heavy rainfall causing serious social and economic consequences, especially in the region’s densely populated cities.
"Heatwaves may lead to high peaks in electricity demand causing possible power outages, many heat-related illnesses that would fill up hospital beds, and crop failure that could threaten food security," said Asst Prof Mengaldo. “Likewise more frequent extreme rainfall may lead to floods, which in turn are a direct threat to human life, buildings and infrastructure, as well as causing other challenges like crop failure, contamination of drinkable water, and landslides.”
The researchers say the findings from their study could help improve climate models and assist governments in better preparing for extreme weather events in the future.
