This past summer a calamity of a scale never before seen in Southasia inundated large parts of India, Nepal and Bangladesh, killing more than 2000 people and displacing some 20 million. UNICEF estimates that Bangladesh was the hardest hit, with nearly 880 people killed and more than 36 million people – a quarter of the population – affected. The floods ended up destroying bridges, schools and roads, and shattering livelihoods for tens of thousands as the waters swept away summertime crops. Several Himalayan rivers burst their banks in the Nepal Tarai, as well as across the border in Bihar and Uttar Pradesh. But even after the waters receded, Bangladesh's weather-related tragedies were not over for the year. In November, Cyclone Sidr, a 'category-four' storm, swept furiously through the country – flattening houses, damaging buildings and roads, and again destroying thousands of acres of crops. Thousands of people died, and approximately 27 million people were affected – many for the second time in six months.
While Southasia has long been used to the annual flooding of the monsoon, the intensity and unpredictability of the region's rains is becoming striking, for lay and scientific observers alike. Indeed, it is unlikely that anyone will soon forget the cataclysmic scenes surrounding the Bombay floods of 2005, when unprecedented rainfall measuring 944 millimetres in just a single day brought India's financial hub to a complete standstill. The city seemed hardly better prepared: Bombay's dilapidated sewer system turned streets into rivers, leading to more than 1100 deaths and losses estimated at more than USD 250 million. The country's previous single-day record for rain had been back in 1910, when 838 mm fell in Cherrapunjee in July of that year.
The heavy precipitation events of the last five years are increasingly being considered as indications of global climate change. Over the past year, weather researchers have warned that Southasia is likely to receive much more unpredictable rain in the coming decades, bringing greater challenges for its governments as they attempt both to prepare for and to cope with nature's seasonal fury. Such unpredictability has serious consequences. For instance, research in villages in semi-arid region of India – central Maharashtra, Andhra Pradesh and Tamil Nadu – during the 1990s found that even slight variations in rainfall timing could reduce profits for poor farmers by more than 30 percent, while having a negligible impact on profitability for the richer farmers.
Finding a cause for the changes in Southasian weather patterns is difficult, as the monsoons have always been notoriously hard to predict. Although global climate change – currently the dominant environmental concern – is nowadays often attributed to any change in the weather, the complexity of monsoon science makes it hard to pin down a direct cause-and-effect relationship. It is clear, however, that extreme weather events have become more common over the last 50 years. Compared to 1951, in 2000 Southasia saw twice as many storms that produced rainfall of more than 150 mm a day, a statistic attributed mainly to the fact that the Indian Ocean got warmer during this period. At the same time, however, storms producing moderate rainfall became rarer, and so the overall rainfall has stayed roughly the same. While the catastrophic floods of 2007 cannot be linked directly to climate change, the impact of climate change in the region is not only very real, but its ramifications are becoming increasingly more dramatic.