Visakhapatnam/Anantapur:Nandyal in Rayalaseema region clocked 46 degrees Celsius in May, for the third consecutive day this year, to become the hottest place in the country. The subsequent heat wave conditions in summer signify the obvious: the region is getting hotter.
Similarly, unusual heavy rains ravaged Vijayawada, causing huge floods that killed 35 persons and affected over 2.5 lakh people. Rayalaseema region resembled a hot summer this week when several of its areas touched 40 degree celsius. An average of 4 degrees C was higher than normal. Such an abnormality was recorded in the region for the first time in 30 years. This had an adverse impact on the standing kharif crops.
Scientist Narayana Swamy of the Rekulakunta research station in BK Samudram in Anantapur district said a temperature of 33.4 to 33.9 degree C was recorded during the transition period when the south west monsoon withdrew and the north east monsoon set in.
High temperature on earth’s surface, floods, sea erosions, rise in sea surface temperatures and freezing temperatures in high altitudes of ASR district are being attributed to the climate change evident in the region since the 1990s.
“Climate change is affecting the timing and intensity of the monsoon seasons in India. Delayed or erratic monsoons leave the land exposed to prolonged periods of heat without the cooling effect of rainfall, thereby increasing the temperatures,’’ said Prof P. Sunitha, head of the department of Meteorology and Oceanography at Andhra University.
Speaking to Deccan Chronicle, Sunitha said gradual increases in temperature have been observed since 1991. These were influenced by rising levels of greenhouse gases and pollutants. A more pronounced rise in land temperatures has been seen since 2001, she said.
This is also the period when feedback mechanisms, such as the accumulation of heat and reduced night-time cooling due to trapped radiation, began to exacerbate the warming effect.
Since 2015, India has witnessed significant spikes in temperatures, leading to more extreme weather events such as heat waves and intense rainfall. This period is marked by stronger monsoon flows, linked to warmer ocean temperatures in the Arabian Sea and Bay of Bengal.
Since the early 20th Century, the Indian Ocean has experienced a steady rise in sea surface temperatures (SST). In the last few decades, this warming has accelerated, especially after the 1980s. The trend is more pronounced in the tropical Indian Ocean, where SSTs have increased by about 1°C since the beginning of the 20th Century, making it one of the fastest-warming ocean basins in the world, Sunitha said.
Since the early 2000s, the Indian Ocean has warmed significantly, with SSTs rising by about 0.15°C per decade. This warming has been more prominent in the western Indian Ocean, including the Arabian Sea.
The western part of the Indian Ocean, especially the Arabian Sea, has experienced faster warming than the Bay of Bengal. The Arabian Sea has warmed at a rate of 1.2°C in the past century.
“The warming of the Indian Ocean SSTs, particularly in the Arabian Sea and Bay of Bengal, has been linked to changes in monsoon dynamics. Warmer SSTs enhance moisture availability and lead to more intense monsoon rains and extreme weather events.”
“Cyclones in the Arabian Sea have become more frequent and intense, as the warmer SSTs provide more energy for storm formation.”
“The warming of the Indian Ocean is not isolated. It is a significant part of global climate change. The absorption of excess heat from global warming has caused the Indian Ocean to warm faster than the Pacific or Atlantic in certain regions, affecting global ocean circulation and weather patterns.”
“The Indian Ocean Dipole (IOD), a climate phenomenon that affects SSTs in the Indian Ocean, also influences the warming trend. In positive IOD years, the western Indian Ocean becomes warmer, impacting regional weather patterns, including stronger monsoons and flooding in parts of India.”
The frequency of positive IOD events has increased in recent decades, further contributing to the rise in SSTs in the western Indian Ocean, Sunitha added.
