Frequent rain, thunderstorms, and clouds have made this year’s pre-monsoon season in Nepal quite unusual. Normally, this time—from March to May—brings dry weather, rising temperatures, and some dust storms. However, many areas are experiencing nearly daily rainfall and storms. Mohan Chand, a glaciologist and environmental science professor at Kathmandu University, noted that this year’s weather diverges significantly from the norm.
This shift is linked to global climate patterns, particularly the El Niño-Southern Oscillation (ENSO). The World Bank identifies ENSO as a key factor in climate variability worldwide. It alternates between El Niño (warm phase) and La Niña (cool phase) on a cycle of three to seven years. Currently, we are leaning toward an El Niño phase.
During El Niño, typical trade winds weaken, allowing warm ocean water to flow toward South America. NASA’s Sentinel-6 satellite recently detected a large area of warm water in the Pacific, a telltale sign of El Niño’s presence.
While the increased rain this spring has led to benefits like cleaner air and more groundwater, it also raises serious risks. These include lightning strikes, hailstorms, landslides, and flash floods. Surprisingly, forecasts suggest that the upcoming monsoon season (June to September) could see below-average rainfall in many parts of Nepal. The Department of Hydrology and Meteorology (DHM) anticipates that provinces like Madhesh and Lumbini will receive the least rainfall.
Mohan Chand explains that we might get bursts of rainfall followed by long dry spells. Meteorologist Ashok Bakhrel adds that western Nepal often feels El Niño’s effects more strongly than the east. Here, river basins such as Karnali and Bheri are more susceptible to droughts during El Niño years.
Residents in western villages share their worries about the unpredictable rainfall patterns. This year, they have noticed that monsoons often deliver either too little rain or sudden, heavy falls, raising concerns about both drought and floods.
Last year serves as a cautionary example. Despite below-average rainfall overall, late-season downpours led to disastrous floods and landslides. Bakhrel highlights that excessive humidity, heat waves, and drought-like conditions may also arise this summer, continuing a troubling trend seen during past El Niño seasons in Nepal.
Interestingly, El Niño isn’t the only climate factor influencing Nepal. Scientists are observing the Atlantic Meridional Overturning Circulation (AMOC). This system plays a key role in global ocean currents but has weakened since the 1850s. Rising ocean temperatures reduce the cold, salty water needed to keep AMOC functioning properly. Chand warns that a slowdown in AMOC could severely impact Nepal’s summer monsoon, exacerbating rainfall variability.
Rijan Bhakta Kayastha, another professor of environmental science, notes that rising temperatures are shrinking glaciers and reducing snowfall in river basins. This not only affects water availability for agriculture but also undermines hydropower production since almost all electricity in Nepal comes from this source.
Another climate driver, the Indian Ocean Dipole (IOD), also deserves attention. Currently neutral but shifting towards a positive phase, a positive IOD could enhance monsoon winds and potentially bring more rain to South Asia.
Despite the predictions for below-normal rainfall this monsoon season, Bakhrel cautions that forecasts are uncertain. Historical data from the DHM indicates that not every El Niño year results in reduced rainfall. A positive shift in the IOD could mitigate some of the El Niño effects.
Experts emphasize that climate change doesn’t respect borders. While it impacts everyone, some regions, like Nepal, bear a heavier burden. As environmental engineer Saksham Shrestha puts it, climate impacts are interconnected and complex. Ultimately, understanding and adapting to these changes is crucial for communities reliant on conventional rainfall patterns.
Source link
