Table of Contents
Relevance: GS Paper III – Environment | Climate Change | Oceanography | Disaster Management | Telangana Current Affairs
For Prelims:
INCOIS, Marine Heatwave, MAHAS, Arabian Sea, Sea Surface Temperature, Coral Bleaching, El Niño, Ocean Stratification, Blue Economy, Potential Fishing Zone, Tsunami Early Warning System, Ministry of Earth Sciences
For Mains:
Climate Change and Oceans, Marine Ecosystem Stress, Fisheries Sustainability, Coastal Vulnerability, Blue Economy, Ocean Governance, Early Warning Systems
Why in News?
The Indian National Centre for Ocean Information Services has reported marine heatwave conditions in the Arabian Sea, with sea surface temperatures exceeding normal limits and crossing the 90th percentile threshold. According to its MAHAS report, different regions are under Watch, Alert, and Warning categories, indicating varying levels of thermal stress. The warming is affecting areas such as the Andaman and Nicobar Islands, India’s eastern coast, and parts of the western coast extending towards Oman, raising concerns over marine ecosystems, fisheries, and coral health.
INCOIS
- The Indian National Centre for Ocean Information Services (INCOIS) is an autonomous scientific institution under the Ministry of Earth Sciences.
- It is located in Hyderabad, Telangana, an important prelims fact because despite dealing entirely with marine and ocean sciences, it is situated in a landlocked inland city.
- It serves as India’s central operational oceanographic institution and provides scientific ocean information and advisory services for fishermen, shipping and maritime navigation, coastal zone management, offshore industries, disaster management authorities, and defence-related maritime operations.
- INCOIS collects data through satellites, ocean buoys, research vessels, underwater sensors, bottom pressure recorders, and real-time forecasting models.
Its major functions include:
- Ocean State Forecasting – It predicts waves, tides, ocean currents, sea surface temperature, and storm surges, which are important for ports, coastal safety, and offshore operations.
- Tsunami Early Warning Centre – INCOIS operates India’s Tsunami Early Warning System for the Indian Ocean Region using seismic and ocean observation networks.
- Potential Fishing Zone (PFZ) Advisory – It identifies areas where fish are likely to aggregate using satellite indicators like chlorophyll concentration and thermal gradients. This helps improve catch efficiency and reduces fuel costs for fishermen.
- Marine Heatwave Advisory Services (MAHAS) – This specialised system monitors sea surface temperature anomalies and provides early warning for marine heatwaves. The present Arabian Sea warning has been issued through this system.
Marine Heatwave: Meaning and Scientific Basis
- A Marine Heatwave is a prolonged period of unusually high ocean temperature in a specific marine region.
- It is not a temporary rise in temperature for one or two days. It is a sustained thermal stress event that affects the functioning of the marine ecosystem. Scientifically, a Marine Heatwave is defined as:
when sea surface temperature remains above the 90th percentile of historical climatological values for at least five consecutive days.
Let us understand this clearly.
Suppose the normal sea temperature of a region during April is based on long-term historical records. If the current sea temperature remains unusually higher than what is observed in 90% of past years, and this condition continues for at least five days, it is classified as a Marine Heatwave.
This makes it different from normal summer warming. It represents persistent abnormal warming and not just seasonal heat. Marine heatwaves are now increasing in frequency, duration, and intensity because of climate change. Earlier they were rare events. Now they are becoming recurring oceanic climate disturbances.
Classification of Marine Heatwaves
Category | Meaning | Impact |
Watch | Initial stage where unusual warming begins and early signs of thermal stress appear | Treated as an advance warning |
Alert | Stronger and more persistent warming conditions | Marine ecosystems begin to experience visible stress; fish productivity and coral health may start getting affected |
Warning | Most serious category with severe and prolonged heat stress | Causes major ecological disruption such as coral bleaching, fish migration shifts, and reduction in ocean productivity |
Causes of Marine Heatwaves
Cause | Explanation |
Global Warming | The long-term rise in Earth’s average temperature due to greenhouse gas emissions is the biggest reason behind rising ocean temperatures. Oceans absorb more than 90% of excess atmospheric heat, making them major heat reservoirs. |
El Niño Events | El Niño alters global atmospheric circulation and weakens normal oceanic cooling systems, leading to widespread abnormal ocean warming. |
Weak Monsoon Winds | Normally, strong winds help vertical mixing of ocean layers and bring cooler water upward. When monsoon winds weaken, this mixing reduces and heat gets trapped near the surface. |
Ocean Stratification | When warm water remains at the top and cooler water stays below without proper mixing, heat accumulates at the surface. This is called stratification and it increases marine heatwave intensity. |
Changes in Ocean Currents | Warm ocean currents can transport higher temperatures into new regions, intensifying local marine heatwaves. This is particularly important in the Arabian Sea. |
Arabian Sea Warming and Indian Ocean Context
- The Arabian Sea is warming faster than many other tropical ocean regions and has emerged as a major hotspot of marine heatwaves in the northern Indian Ocean.
- It lies to the west of India and is bounded by India, Pakistan, Iran, Oman, Yemen, Somalia, and the Maldives. It connects to the Red Sea through the Gulf of Aden and to the Persian Gulf through the Gulf of Oman and the Strait of Hormuz.
- Compared to the Bay of Bengal, the Arabian Sea was traditionally considered less cyclone-prone due to relatively cooler waters and stronger vertical wind shear.
- However, in recent years, rising Sea Surface Temperature (SST) has increased the frequency and intensity of cyclones in the Arabian Sea.
Examples include Cyclones Tauktae, Nisarga, Biparjoy, and Tej, which showed unusually high intensity.
This warming directly affects:
- Southwest Monsoon behaviour
- Cyclone formation and rapid intensification
- Coral reefs and marine biodiversity
- Fisheries productivity, especially tuna and deep-sea species
- Coastal livelihoods and maritime economy
- The Arabian Sea also plays an important role in the Indian Monsoon system because warm SST enhances moisture supply for monsoon winds.
- Marine heatwaves in this region are now spreading along India’s western coast, towards Oman, the southern Indian Ocean, Mauritius, South Africa, and Western Australia, indicating a broader Indian Ocean warming pattern rather than an isolated regional event.
- This is important for prelims because increasing Arabian Sea warming is directly linked to climate change, monsoon variability, stronger cyclones, and marine ecosystem stress.
CARE MCQ
Q. With reference to Marine Heatwaves, consider the following statements:
- Marine heatwaves are periods of abnormally high sea surface temperature persisting for several days or weeks.
- Marine heatwaves improve coral reef health and increase fish productivity in affected regions.
- The Arabian Sea has witnessed a rise in marine heatwave events in recent years.
Which of the statements given above are correct?
(a) 1 and 3 only
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1, 2 and 3
Answer: (a) 1 and 3 only
Explanation
Statement 1: Correct
Marine heatwaves occur when sea surface temperatures remain significantly above normal for an extended period. They are the oceanic equivalent of heatwaves on land.
Statement 2: Incorrect
Marine heatwaves damage coral reefs through bleaching, reduce fish availability, disturb marine food chains, and negatively affect fisheries.
Statement 3: Correct
The Arabian Sea has become more vulnerable to marine heatwaves because of rising sea surface temperatures, which also contribute to stronger cyclones and ecosystem stress.
Q.With reference to Marine Heatwaves (MHWs), consider the following statements:
- Marine heatwaves are primarily identified on the basis of prolonged abnormal rise in sea surface temperature.
- Marine heatwaves can increase the intensity of tropical cyclones by providing additional heat energy.
- The Bay of Bengal experiences marine heatwaves, while the Arabian Sea remains largely unaffected due to its deeper waters.
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Answer: (a) 1 and 2 only
Statement 1: Correct
Marine heatwaves are defined as periods of unusually high sea surface temperatures that persist for several days or weeks in a specific marine region.
Statement 2: Correct
Warmer sea surfaces provide more latent heat energy, which can strengthen tropical cyclones and support rapid intensification.
Statement 3: Incorrect
The Arabian Sea has also emerged as a major hotspot of marine heatwaves in recent years. In fact, increasing sea surface temperatures in the Arabian Sea have contributed to stronger cyclones and ecological stress.
Q. With reference to Marine Heatwaves, consider the following statements:
- A Marine Heatwave occurs when sea surface temperature remains above the 90th percentile of historical values for at least five consecutive days.
- The Indian National Centre for Ocean Information Services (INCOIS) functions under the Ministry of Environment, Forest and Climate Change.
- Marine Heatwave Advisory Services (MAHAS) is operated by INCOIS from Hyderabad.
Which of the statements given above are correct?
(a) 1 and 3 only
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1, 2 and 3
Answer: (a) 1 and 3 only
Statement 1: Correct
A Marine Heatwave is scientifically defined as a period when sea surface temperature remains above the 90th percentile of historical observations for at least five consecutive days. It represents an unusually prolonged warming event in the ocean.
Statement 2: Incorrect
INCOIS functions under the Ministry of Earth Sciences (MoES), not under the Ministry of Environment, Forest and Climate Change. It is India’s premier institution for ocean information and advisory services.
Statement 3: Correct
Marine Heatwave Advisory Services (MAHAS) is a specialised system operated by INCOIS for monitoring sea surface temperature anomalies and issuing early warnings for marine heatwaves. INCOIS is headquartered in Hyderabad, Telangana.
Therefore, the correct answer is (a) 1 and 3 only.
Q.Sea Surface Temperature (SST) refers to:
(a) Temperature of water at the ocean floor
(b) Temperature of the uppermost layer of the ocean
(c) Temperature of underground seawater reserves
(d) Temperature of ocean currents below 500 metres
Answer: (b) Temperature of the uppermost layer of the ocean
Explanation:
Sea Surface Temperature (SST) is the temperature of the top layer of ocean water, which directly interacts with the atmosphere and plays an important role in monsoon formation, cyclone intensity, and marine heatwaves.
TGPSC Mains Question
Q. Rising marine heatwaves are emerging as a major threat to India’s blue economy and coastal sustainability. Discuss.
(250 words)
FAQs
Q1. What is the minimum duration for a Marine Heatwave?
At least five consecutive days.
Q2. Which institution monitors Marine Heatwaves in India?
INCOIS through its Marine Heatwave Advisory Services (MAHAS).
Q3. Where is INCOIS located?
It is located in Hyderabad, Telangana.
Q4. Why is Arabian Sea warming important?
Because it affects fisheries, cyclones, coral reefs, and the Indian monsoon system.
Q5. Why is this important for Telangana exams?
Because INCOIS is one of India’s most important scientific institutions located in Hyderabad.
