1033. Climate Change's Impact on Heat Waves and Monsoons

A record-breaking heat wave has been reported in India. Although it is usually hot in India during this period of April and May, it is rare to observe a prolonged heat wave for three consecutive years. An op-ed in the journal Nature on May 29 suggests that human-induced climate change may be increasing the frequency and intensity of these extreme weather events.

In India, the monsoon season, which corresponds to the rainy season, is coming, and an editorial in Nature on May 28 notes that climate change is also altering monsoon patterns in India, and that the varying impacts across the regions necessitate the implementation of local adaptation measures.

The monsoon, which originally means "mausim (change in wind direction due to the seasons)" in Arabic, is extremely important for people's lives and economies. Normally, from June to September, rainfall tends to increase in the Indian subcontinent due to the southwest monsoon bringing humidity, and conversely, from October to December, the northeast monsoon brings rain to southern India.

In recent years, India's rainfall patterns have seen significant fluctuations, which have had a significant impact on the agriculture and water management sectors. The historically arid regions of Rajasthan, Gujarat, and Maharashtra have seen a 10–30% increase in southwest monsoon rainfall over the past decade compared to the previous 30 years. In contrast, nearly 11% of Indian municipalities have seen a decrease of more than 10% in rainfall during the southwest monsoon, corresponding to the agriculturally important Indo-Gangetic Plain, the fragile Himalayan region (from which many endemic crop species originate), and  northeastern India, the region that receives the highest rainfall in the world.

The editorial called for strengthening weather monitoring systems, enhancing the adaptive capacity of the agricultural sector, which is important for India's economy and employment, and more precise data analysis to prepare for changing monsoon rainfall patterns. With regard to rainfall, it is often more important to predict changes in seasonal distribution than total annual rainfall, and data analysis is required to manage risk and assess impact at precise granularity. In addition, forecasting in the relatively short term is becoming increasingly important for adaptation measures.

The editorial also took into account the possibility of floods and droughts occurring in the same region during the season, and called for the need to strengthen the collection of microclimate data at the local level. The editorial also noted that solving the challenges posed by irregular monsoons in India could provide lessons for countries in the Global South facing extreme rainfall and flooding, such as Afghanistan, Kenya, Brazil, and Indonesia.

Contributor: IIYAMA Miyuki, Information Program