Marine Heat Waves in Oceans Are Increasing: It Matters More Than You Think

The Indian Ocean is headed towards a near-permanent state of heat waves.

(Photo: iStock/Altered by The Quint)

The Indian Ocean is headed towards a near-permanent state of heat waves. This is what a recent study, titled Future Projections for the Tropical Indian Ocean, has suggested.

The study, underlining the concerns posed by marine heat waves, said:

“Marine heatwaves are projected to increase from 20 days per year (during 1970–2000) to 220–250 days per year, pushing the tropical Indian Ocean into a basin-wide near-permanent heatwave state by the end of the 21st century.”

It also mentioned that “the rapid warming in the Indian Ocean is not limited to the surface.” 

What does all this mean? Can warmer air in the oceans affect our lives in any way? Is this something policymakers need to pay heed to?

The Quint spoke to experts – Abinash Mohanty, Sector Head, Climate Change & Sustainability at IPE Global, and Expert Reviewer of IPCC- AR(6), and Kavin Kumar Kandasamy, CEO, ProClime – to understand how marine heat waves can impact us.

Marine Heat Waves: The What & the Why

First of all, what is a marine heat wave? 

According to the Center for Climate Change Impacts and Adaptation in the United States, “A marine heatwave is a period of unusually high ocean temperatures and is defined by its duration and intensity.”

And why exactly do they happen? Abinash Mohanty explains that heat or warm air always travels from a place of high potential to that of low potential.

Due to human activity, a lot of heat is emitted on land, which then travels to the sea and oceans and ends up disrupting the routine cyclogenesis processes.

The oceans have also been getting warmer lately because of increased global warming. 

Impact of Marine Heat Waves Not Limited to the Sea

The first line of impact of marine heat waves is on the biodiversity in the oceans (like the coral reefs). And what follows is affecting those who depend on it.

Mohanty says that due to different thermal comfort levels and anthropocentric activities, marine species get trapped in the ocean when heat waves happen and can end up being suffocated – which means that coral reefs and mangroves, for instance, are affected due to increasing ocean temperatures.

In the first week of May, news had broken out that, according to the Central Marine Fisheries Research Institute, marine heat waves in the Lakshadweep sea had caused severe bleaching in the coral reefs since October 2023.

But the impact isn't just limited to them. Kavin Kandasamy tells The Quint,

“There are many communities that live in the coastal areas of India whose livelihoods are dependent on the biodiversity of the coastline. By the frequent increase of marine heat waves, biodiversity impact will affect the economic conditions of these people. This can cause large-scale climate migration. We would lose a lot of carbon sequestration potential that coastlines have.”

This doesn’t mean that marine heat waves impact only those who live in coastal areas. Kandasamy adds that the shoreline erosion and the adverse effects on the weather patterns are felt by inland communities too. 

“Marine heat waves don’t just impact the sea, but over all cyclogenesis processes and weather phenomena too,” Mohanty also warns.

He says that marine heat waves can lead to increased cyclones, deep depressions aggravating faster, erratic rainfall, dust storms, hail storms, delayed monsoons, cloud bursts, and intensification of other weather anomalous patterns. 

He adds, “Marine heat waves also aggravate the already existing heat stresses on the land. It’ll lead to extended summer months and extended heat stress conditions.”

This is something, Mohanty mentions, that we’ve already been seeing in the Arabian Sea lately, where aggravated weather phenomena have increased, in comparison to the Bay of Bengal.

He stresses that increasingly heat being trapped between the land and oceans has been making extreme weather events our ‘new normal’.

‘Increase Biodiversity’: Preventing Marine Heat Waves

But is there anything at all that we can do to prevent marine heat waves? There is. The experts that The Quint spoke to suggest:

• Increase marine species density that can sequester more carbon

• Increase biodiversity footprints

• Increase green cover and forest cover in cities

“We should also map these marine heat waves, to understand and mitigate them better. Study marine heat waves in a hypergranular way. Study how they impact the ocean, marine biodiversity, and its attribution to life on land and then use it for targeted action.”

Abinash Mohanty