On Wednesday, a rapid attribution analysis revealed that the extreme humid heat wave which affected eastern and northern regions of India, Bangladesh, Laos, and Thailand in April was significantly intensified by climate change, making it at least 30 times more probable.
According to the World Weather Attribution group, an international team of scientists, their analysis indicates that a highly vulnerable population faced a dangerous combination of elevated heat and humidity during the early summer this year, with climate change playing a significant role. Specifically, in South Asia, large numbers of people experienced extreme heat indices or “feels like” temperatures exceeding 41 degrees Celsius over a four-day period from April 17 to 20. Certain areas, particularly in Laos, even recorded heat indices surpassing 54 degrees Celsius, which can be deadly. The findings of the World Weather Attribution’s report align with a statement released by the World Meteorological Organization on Wednesday, which warned that there is a 66% probability that the average global temperature between 2023 and 2027 will exceed 1.5 degrees Celsius above pre-industrial levels for at least one year.
Last March and April, both India and Pakistan encountered a severe heatwave. The 2022 heatwave is estimated to have resulted in approximately 90 fatalities across the two countries, triggering an extreme Glacial Lake Outburst Flood in northern Pakistan, forest fires in India, reduced wheat crop yields in India, and power outages affecting millions of people. Scientists from the World Weather Attribution group previously stated that the climate crisis had made such an event 30 times more probable. However, they now report that while India experienced a dry heat episode last year, this year it affected more humid and coastal regions of the country.
In April, certain areas in South and Southeast Asia experienced an intense heatwave, with temperatures surpassing records, reaching over 44 degrees Celsius in eastern India, 42 degrees Celsius in Laos, and 45 degrees Celsius in Thailand. This extreme heat resulted in widespread hospitalizations, road damage, fires, and school closures. The exact number of fatalities is still unknown, as per the scientists’ statement.
On April 15, Dhaka, Bangladesh experienced its highest maximum temperature in decades, reaching 40.6 degrees Celsius. In India, several cities in the northern and eastern regions recorded maximum temperatures above 44 degrees Celsius on April 18. Thailand also witnessed its all-time highest temperature of 45.4 degrees Celsius in the city of Tak on April 15. The Sainyabuli province in Laos set a national temperature record of 42.9 degrees Celsius on April 19, while the capital city of Vientiane reached 41.4 degrees Celsius on April 15, marking its hottest day ever. Luan Prabang in Laos reported 42.7 degrees Celsius on the same day.
The analysis reveals a sudden increase in heat-related illnesses, electricity demand, and casualties. On April 16, in Navi Mumbai, Maharashtra, there were approximately 13 reported casualties and around 50-60 hospitalizations due to heat stroke, although other sources mention 650 hospitalizations. Thailand also reported casualties. The analysis further states that the true impact on human lives will only become clear months after the event. In India, specifically in the states of West Bengal, Tripura, and Odisha, schools closed three weeks earlier than scheduled due to the extreme heat. Additionally, a significant number of forest fires occurred during the same period in India, Thailand, and Laos, as highlighted in the analysis released on Wednesday.
A collaboration of scientists from India, Thailand, France, Australia, Denmark, Germany, Kenya, the Netherlands, the US, and the United Kingdom conducted an assessment to understand how the climate crisis increased the likelihood of the April heatwave. By employing peer-reviewed methods and analyzing available datasets, the scientists examined how climate change influenced both the probability and intensity of the four-day heatwave event in April. The impact of the heatwave was measured using a heat index that combines temperature and humidity. The analysis, which was released on Wednesday, has not yet undergone peer review but is expected to undergo the process soon.
Given the high levels of humidity during the heatwave, the heat index values were higher than the actual temperatures recorded. To ensure a clear assessment, the team excluded the dry, semi-arid region that runs parallel to the Western Ghats, where humidity is low during the pre-monsoon season. The heat index values determined by the team surpassed the threshold considered as “dangerous” (41 degrees Celsius) across large portions of the studied South Asian regions this year. In some areas, the values reached the “extremely dangerous” category (above 54 degrees Celsius), where maintaining normal body temperature becomes challenging, according to the scientists.
In order to understand the impact of climate change on extreme heat, the team of scientists combined observations and models, taking into account the average global temperature increase of 1.2 degrees Celsius. Their analysis revealed that current warming levels have amplified the likelihood of such an event occurring in India and Bangladesh by a factor of at least 30. Additionally, a heatwave that previously had a 20% chance of occurring in any given year over India and Bangladesh is now approximately 2 degrees Celsius hotter in terms of the heat index due to global warming.
Looking ahead, the likelihood of a similar heatwave event in April recurring would increase by a factor of about 3 between the present and when global warming reaches 2 degrees Celsius. This means that such an event could be anticipated every 1-2 years, according to the analysis. These findings highlight the escalating impact of climate change and the increasing frequency and severity of heatwaves in the region as global temperatures continue to rise.
