This April, sea surface temperatures (SSTs) around the world are at their highest levels ever. Notably, the Indian Ocean region is being affected by incredibly high SSTs, especially in the south Arabian Sea and the Bay of Bengal.
The University of Maine’s Climate Change Institute reported that on April 5th, the global average SST was 21.1 degrees Celsius – a new record. Following that, on April 16th, it was still 21 degrees Celsius, tying the previous record set in March 2016.
The University’s Climate Reanalyzer utilized data from NOAA to discover that SSTs over the tropics are higher than usual, particularly in the Indian Ocean, where temperatures between 29-31 degrees Celsius were seen on Sunday, nearing the highest temperature range on NOAA’s chart.
It is speculated that if these high SSTs continue, serious consequences can arise with regard to monsoons, such as delayed onset or heavier rain events.
Additionally, INCOIS advised that SSTs in both the south Bay of Bengal and the south Arabian Sea could reach 30 degrees Celsius this week, according to their predictions – a record high.
The Marine Heat Wave Tracker from the Marine Heatwaves International Working Group further explained how intense heat waves are currently being felt all over these two regions, in particular along Kerala and Karnataka (south Arabian Sea) and Bangladesh and West Bengal (Bay of Bengal).
Even though heat waves may be short-lived occurrences, scientists caution that any temperatures above 30 degrees Celsius cannot be taken lightly.
Rajeevan, a climate expert and former secretary of the Ministry of Earth Sciences, notes that when sea surface temperatures (SSTs) go above 30 degrees Celsius, it can have a major impact on marine life, both good and bad.
On the one hand, warm SSTs can assist in the development of low-pressure systems and the formation of depressions for rain during the monsoon season. On the other hand, high ocean temperatures might lessen the temperature differential between land and sea, which hinders the commencement of monsoon activities and rainfall.
Rajeevan explains this is due to elevated solar radiation combined with ocean dynamics – something that is more complicated than land-based systems since land heats up faster than oceans. This cooling-off process usually occurs after monsoon season arrives in the Arabian Sea.
Whenever El Nino occurs in the Pacific, the winds and atmospheric circulation cause the Indian Ocean to become warmer.
This warming is increased by climate change and is visible as higher than usual sea surface temperatures in areas such as the Arabian Sea, northern and southern Bay of Bengal, and central equatorial Indian Ocean at around 1-2 degrees Celsius above average.
As a result, NOAA has issued a maritime heatwave warning. These heatwaves have devastating effects, such as coral bleaching and fish death.
El Nino conditions and ocean warming are expected to remain until May-June, according to international institutions, potentially weakening monsoon winds and reducing rainfall while also increasing rainfall in other areas.
To avoid potential risks caused by these changing climatic patterns, Koll emphasizes the need for long-term policy changes.
The Intergovernmental Panel on Climate Change’s Special Report on the Ocean and Cryosphere report that since 1970, global ocean temperatures have risen steadily, with an even more rapid increase since 1993, which has led to an increase in marine heatwaves of double their 1982 frequency since then.
In addition, ocean surface acidity has increased due to higher CO2 absorption resulting in oxygen depletion from the surface down to 1000 meters deep.
Source: Marine Insight
