This Indian summer is going to heat up. The India Meteorological Department (IMD) has suggested that the months of March- May are likely to be hotter than usual across most parts of the country, while predicting the prevalence of El Nino conditions for most of this period, resulting in heatwaves.
With even the election and holiday seasons landing at the same time, temperatures are due to soar further, clocking well above the 40-degrees Celsius threshold. With climate change and global warming on the rise, summers are rarely the pleasant long months that children looked forward to, but rather hellish days we now push forward. In the past years, the persistence of the El Nino effect during the summer months has been attributed to cause higher temperatures.
El Nino is a climate phenomenon, characterised by the periodic warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean. During El Nino, trade winds are weakened, the warm water is pushed back east and toward the west coast of America. The effect can affect weather significantly, especially making days much hotter and drier, with limited scope for moisture, and thus less rainfall.
During this process, the temperatures on the warmer-than-average sea surface alter atmospheric circulation patterns and thus influence weather conditions. While the El Nino is the warm phase of the larger phenomenon called the El Nino-Southern Oscillation (ENSO), the La Nina is the ‘cool phase’ of ENSO. It is a pattern that describes the cooling of the region’s surface waters. The two effects are considered as the ocean part of ENSO and the Southern Oscillation is its atmospheric changes. The Southern Oscillation is a change in air pressure over the tropical Pacific Ocean and the El Nino occurs simultaneously with the Southern Oscillation. When coastal waters become warmer in the eastern tropical Pacific, the atmospheric pressure above the ocean decreases.
Further, during an El Nino event, westward-blowing trade winds are weakened along the Equator. These changes in air pressure and wind speed cause warm surface water to move eastward along the Equator, from the western Pacific to the coast of northern South America. The warm surface water deepens the level of ocean depth that separates warm surface water from the colder water below.
During an El Nino event, this level can drop to 152 metres. Thus, a thick layer of warm water does not allow normal upwelling (the process in which deep, cold water rises toward the surface) to occur. On the other hand, La Nina is a climate pattern that cools the surface ocean water, along the tropical west coast of South America. La Nina is considered as the counterpart to El Nino.
According to the National Oceanic and Atmospheric Administration (NOAA): “El Nino and La Nina can both have global impacts on weather, wildfires, ecosystems, and economies. Episodes of El Nino and La Nina typically last nine to 12 months, but can sometimes last for years. El Nino and La Nina events occur every 2-7 years, on average, but they don’t occur on a regular schedule.”
Global weather agencies predict that the La Nina could return between April and September, bringing in cooler temperatures and rainfall, including in India during the monsoon. It’s a natural cycle on Earth.