Over the past 50 years, according to data from the Indian Meteorological Department, the frequency and magnitude of extreme rainfall events has increased over central India during the monsoon, while moderate events have decreased.
This is a major problem. The moderate rainfall events are needed to feed crops and recharge aquifers, while extreme events often lead to flooding in both rural and urban areas. Scientific modeling suggests that the overall atmospheric circulation that drives the monsoon system is weakening, leading to extreme events early in the season, followed by increased droughts toward the end. Local rainfall records and ice core data also suggest a decrease in overall monsoon strength over the past century over the Himalayan region.
Science also confirms that the region is warming at two to three times the global average rate. Since 1900, the region’s average temperature has increased by 1.2 degrees Celsius, and most of this warming has occurred over the past 30 years. Extreme heat waves have become more frequent.
So what is driving the climate changes that affect the Himalayan region? Strong evidence points to two sources: 1) general global warming, the result of carbon dioxide buildup in the atmosphere; and 2) region-specific warming due to black carbon. This black carbon – emissions from unburned fuel and soot – are mainly emitted from India’s fleets of diesel vehicles, small brick kilns, cookstoves, and coal-based power plants.