Global Warming May Intensify Mei-yu Weather in East Asia
| Policy Research and Advocacy Team, Friends of the Earth (HK)
Global warming, driven primarily by human activities, has become one
of the most pressing environmental challenges of our time. Its far-reaching
impacts extend beyond rising temperatures and melting ice caps. Climate
scientists have increasingly turned their attention to its influence on
regional weather patterns.
Mei-yu, also known as the East Asian rainy season, is a climatic
phenomenon observed in East Asia, particularly in China, Japan, and the Korean
Peninsula. It occurs during the transition from spring to summer when a
persistent rain belt forms over the region.The Mei-yu season is characterised by heavy rainfall, high humidity, and
frequent thunderstorms, which can lead to flooding and landslides. While it is
challenging to attribute individual weather events to climate change, there is
mounting evidence suggesting a link between the intensification of Mei-yu
weather and global warming.
Meiyu rain belt cloud cover
parts of southern China, Taiwan and Okinawa Islands (Image source: WorldView
One of the key mechanisms by which global warming affects Mei-yu
weather is through the warming of the atmosphere. As temperatures rise, the
atmosphere can hold more moisture, leading to increased atmospheric water vapor
content.This enhanced moisture availability can fuel the intensity of rainfall during
the Mei-yu season, potentially resulting in more frequent and severe downpours.
Earth's water cycle (Image
The warming of the oceans due to global warming can also impact
Mei-yu weather. Sea surface temperature anomalies have been linked to
variations in the intensity and duration of the rainy season.Warmer sea surface temperatures can provide additional energy and moisture to
the atmosphere, contributing to the intensification of rainfall.
The potential intensification of Mei-yu weather has significant
implications for East Asia. It plays a crucial role in agricultural production
in East Asia, providing essential water resources for crops. However, excessive
rainfall during this period can lead to waterlogging, soil erosion, and crop
damage.Changes in the intensity and timing of rainfall associated with Mei-yu may
require adjustments in agricultural practices and water management strategies
to ensure food security.
Crop damage due to heavy
rainfall in China (Image source: China Daily)
The increased risk of flooding and landslides associated with
intensified Mei-yu weather poses challenges to infrastructure and urban
planning. East Asian cities must develop robust drainage systems, flood control
measures, and urban design strategies that can withstand the impacts of heavier
rainfall.Additionally, improved forecasting and early warning systems are crucial for
minimising the potential damage to infrastructure and ensuring public safety.
The intensification of Mei-yu weather can also impact public health.
Heavy rainfall can contribute to the spread of waterborne diseases and increase
the risk of vector-borne illnesses such as dengue fever.Adequate public health infrastructure, including sanitation systems and disease
surveillance, is essential to mitigate these risks and protect vulnerable
Health tips after floods
(Image source: World Health Organisation)
In response to the potential intensification of Mei-yu weather, the
Hong Kong government should prioritise the implementation of effective
adaptation and mitigation strategies. This includes investing in comprehensive
flood management systems that incorporate green infrastructure, such as rain
gardensand permeable surfaces,to absorb and manage excess rainfall.
Rain Garden at Uppsala,
Sweden (Image source: Trafikverket)
Additionally, the government should enhance the maintenance and
expansion of drainage networks, ensuring they are capable of handling increased
volumes of water during intense rainfall events.Collaborating with regional and international partners to share knowledge, best
practices, and technological advancements in flood management can further
strengthen Hong Kong's resilience to heavy rainfall associated with Mei-yu
Global warming has the potential to intensify the Mei-yu season in
East Asia, leading to more frequent and severe rainfall events. Urgent action
to reduce greenhouse gas emissions is vital to limit the extent of global
warming and its associated impacts on regional weather patterns. By
implementing proactive measures and investing in resilience, East Asian
countries like Hong Kong can better prepare for the potential challenges posed
by intensified Mei-yu weather in the future.