The Importance of the Indian Ocean for Every Indian

The Importance of the Indian Ocean: Why It Reaches Every Indian, Coast or Not

Published: 24 September 2026

Aerial view of the Indian Ocean coastline, rainfed farmland and a storm system approaching the coast | India | Ocean Evoke India

If you live in Nagpur or Jaipur or Lucknow, the sea is a holiday. It is not where your water comes from. Except that it is. The rain that fills your taps and grew the grain on your plate this morning was ocean water a few days earlier, lifted off the Indian Ocean and carried inland by a wind that changes direction once a year. In western and central India, more than 90 per cent of the year’s rain arrives in the four months from June to September, according to the NOAA Climate Prediction Center. In southern and north-western India the figure is 50 to 75 per cent. That is the importance of the Indian Ocean stated at its most direct. Almost every drop you use passes through it first.

How an ocean you have never seen delivers your rain

Land and water do not heat at the same speed. Through spring, the Indian landmass warms quickly while the ocean to the south stays comparatively cool. Warm air over the land rises, pressure falls, and air flows in from the sea to replace it. That flow crosses hundreds of kilometres of open water on the way, and it picks up moisture the whole distance. When it reaches land and rises over terrain, the moisture falls out as rain.

The word monsoon describes the wind, not the rain. The rain is what happens afterwards. Twice a year the wind reverses: in from the sea in summer, back out towards it in winter. It is the reversal that defines the system, and it is the reason the rain is seasonal rather than scattered through the year.

That distinction matters more than it sounds. If the monsoon were simply a rainy season, its failure would be bad luck. Because it is a wind system driven by the temperature difference between a continent and an ocean, anything that changes the ocean changes the rain. Modern research treats the monsoon as a coupled system in which the sea is not only the trigger but the moisture supply. Work on the IITM Earth System Model, published in Climate Dynamics, treats moisture transport from the Indian Ocean as central to how much rain the system actually delivers.

So the honest version is this. The temperature contrast starts the wind. The ocean fills it with water. Both parts have to work.

Diagram showing seasonal reversal of Indian Ocean monsoon winds, with summer winds bringing moisture toward India and winter winds flowing offshore | India | Ocean Evoke India

Why the monsoon is not the same every year

Every year the rain arrives. Some years it arrives short. One reason sits in the ocean itself.

The tropical Indian Ocean does not warm evenly. In some years the western side, towards Africa, runs warmer than usual while the eastern side, towards Indonesia, runs cooler. In other years it tips the other way. Scientists call this see-saw the Indian Ocean Dipole.

When the western side is the warmer one, the phase is called positive, and positive phases tend to be associated with above-normal monsoon rainfall over India. The mechanism is reasonably well understood: warmer water in the west and cooler water in the east strengthen the winds along the equator, which push more moisture into the monsoon flow.

Two cautions belong with that sentence, and most coverage leaves them out.

The effect is a tendency, not a rule. A 2025 study in Geophysical Research Letters found the impacts of extreme positive and negative dipole events on late-summer monsoon rainfall are asymmetric rather than mirror images of each other.
The dipole does not act alone. It interacts with El Nino in the Pacific, so no single season’s rainfall can be pinned on it.

If you take one thing from this section, take the shape rather than the forecast. The monsoon varies because the ocean varies. Nobody can tell you in April what August will bring.

Where the importance of the Indian Ocean reaches inland

Here is where the mechanism reaches inland.

About 51 per cent of India’s net sown area is rainfed, and that land accounts for roughly 40 per cent of total food production, according to the Department of Agriculture and Farmers Welfare. Net sown area is a specific measure: land sown with crops at least once in an agricultural year, counted once. So this is not a statement about half of India’s territory. It is a statement about half of the land that actually grows food.

Rainfed means exactly what it says. No canal, no borewell, no reservoir standing between a failed monsoon and a failed crop. For that half of India’s cropped land, the Indian Ocean is the irrigation system.

The figure is not fresh. The most recent stated basis is 2022, and the departmental page carries no year at all, so treat it as the order of the thing rather than this season’s number. Even allowing for that, the scale is the point. An inland farmer working unirrigated land is as exposed to what happens over the Arabian Sea as a fisher working from a coastal harbour, and considerably less likely to think of themselves that way.

What the sea itself puts on the table

The ocean also delivers food directly, and the numbers here are recent.

India landed an estimated 3.47 million tonnes of marine fish in 2024, about 2 per cent below the 2023 figure, according to the ICAR-Central Marine Fisheries Research Institute. Gujarat led at 7.54 lakh tonnes, followed by Tamil Nadu at 6.79 lakh and Kerala at 6.10 lakh. Indian mackerel was the most landed species at 2.63 lakh tonnes, with oil sardine close behind at 2.41 lakh.

One qualification matters. That is marine capture only. It excludes inland fisheries and aquaculture, which together are larger. Anyone quoting 3.47 million tonnes as India’s fish production is quoting the wrong number.

CMFRI attributed part of the 2024 decline to cyclonic storms, naming Dana, Fengal, Remal and Asna as disruptions to fishing activity. That is worth holding on to for the last section of this article.

Behind the tonnage are people. The Marine Fisheries Census of 2010 counted 3,288 marine fishing villages, 1,511 landing centres and 864,550 fisher households across the maritime states and union territories, which puts the marine fisherfolk population at roughly four million. Those counts are now fifteen years old. A fifth census is under way: the Department of Fisheries, working through CMFRI, is enumerating around 1.2 million fisher households across about 3,500 villages in 13 coastal states and union territories. The newer figure is substantially larger, which is the clearest reason not to treat the 2010 counts as today’s picture.

Fishing pressure is not the only thing these waters carry. Our separate pieces on plastic pollution in Indian oceans and on India’s endangered marine animals cover what else is changing in the same fishing grounds.

Almost everything you own arrived by sea

Think about the weight of the things you use. Not their price, their weight. About 95 per cent of India’s trade by volume moves by sea, a figure attributed to the Ministry of Ports, Shipping and Waterways and repeated independently by officials at the Directorate General of Shipping.

By value the share is lower, because ships carry the heavy and cheap while aircraft carry the light and expensive. Official statements put it somewhere close to seven tenths, though they do not agree on the exact number, so no precise figure appears here.

The volume share is the one that describes daily life. Shipping is how bulk moves anywhere in the world: fuels, minerals, grains, industrial inputs, and containers of finished goods. For India, that traffic runs across the Indian Ocean. It is not a trade route the country happens to sit beside. It is the surface almost all of India’s physical trade travels on.

India’s coastline got longer in 2025 without moving

In April 2025 the Ministry of Ports, Shipping and Waterways issued a circular revising India’s official coastline length from 7,516.60 km to 11,098.81 km. The coast did not change. The ruler did.

The older figure was computed in the 1970s from maps at a scale of 1:4,500,000 or smaller, using manual methods. The revision was computed by the National Hydrographic Organisation with the Survey of India at a scale of 1:250,000, using GIS software, and it included offshore islands the earlier count had left out.

This is a well-known property of coastlines. Measure a coast with a long ruler and you cut across every bay and inlet. Measure it with a short one and you follow them in, and the total grows. The finer the scale, the longer the answer. So the older figures were not wrong for their scale, which is why plenty of sources still quote 7,516 km, and some quote 8,118 km. They were answering the same question with a coarser instrument.

Beyond the coast, India holds rights over about two million square kilometres of sea as its exclusive economic zone. Rights over resources is the precise phrase. It is not ownership of the water, and it does not permit India to bar other countries’ ships from passing through. How much of that water is actually protected, and how well, is the subject of our guide to marine protected areas in India.

[Suggestion: In-article visual: place after “India’s coastline got longer in 2025 without moving”: image comparing the same stretch of coast traced twice, once with long straight segments that cut across bays and once with short segments that follow every inlet, each with its own total length beside it, so the reader can see that a longer number came from a finer measurement rather than from any change to the land.]

The Indian Ocean is warming faster than it used to

Everything above assumes the ocean behaves as it has. It is not going to.

Research led by Roxy Mathew Koll of the Indian Institute of Tropical Meteorology in Pune, with Thomas Frolicher of the University of Bern, published in 2024 as part of an Elsevier volume on the Indian Ocean’s role in the global climate system, puts the observed surface warming of the Indian Ocean at about 1.2 degrees Celsius per century over 1950 to 2020. For 2020 to 2100 the projection is 1.7 to 3.8 degrees Celsius per century.

Read those as rates, not as warming already banked. And read the projection as a range, because it spans different emissions futures rather than describing one.

The same work projects marine heatwaves, meaning stretches of days when sea temperature stays unusually high for that place and season, rising from roughly 20 days a year to somewhere between 220 and 250 days a year. At that frequency the tropical Indian Ocean approaches a near-permanent heatwave state. The reports of this projection differ on the horizon, so no date is given here.

A warmer ocean holds and gives up more moisture, and it is the same ocean that supplies the monsoon and hosts the fisheries in the sections above. That is the link worth holding: this is not a separate environmental topic sitting alongside rain and food. It is a change in the system that produces them.

What is already different on the west coast

Some of this has stopped being a projection.

Research led by Medha Deshpande at the Indian Institute of Tropical Meteorology, published in Climate Dynamics in 2021, examined cyclones over the north Indian Ocean from 1982 to 2019. In the recent part of that record, 2001 to 2019, the frequency of cyclonic storms over the Arabian Sea rose about 52 per cent, while the Bay of Bengal saw a decrease of about 8 per cent. Storm duration rose about 80 per cent. Intensity rose about 20 per cent before the monsoon and about 40 per cent after it. Very severe cyclones increased about 150 per cent.

One correction, because the headline figure invites a wrong conclusion. The Arabian Sea increase is from a much lower base. The Bay of Bengal has always produced far more cyclones, and a 52 per cent rise on a small number does not overtake it. What changed is that India’s west coast, which used to treat cyclones as an eastern problem, no longer can.

Note also that the record ends in 2019. This is a documented shift over a defined window, not a running commentary on this year.

Put it beside the fisheries figures and the sections stop being separate. CMFRI named four cyclones as a factor in the 2024 landings decline. The mechanism runs from a warmer ocean to more and longer storms to fewer fishing days to less fish landed. Each link in that chain is measured by a different institution, which is precisely why it is easy to miss.

Conclusion

The importance of the Indian Ocean to an Indian reader is not a matter of opinion or coastline proximity. About 51 per cent of India’s net sown area depends on rain that the ocean supplies, the sea landed 3.47 million tonnes of fish in 2024, and about 95 per cent of the country’s trade by volume crosses it. Those are three different systems reaching three different groups of people, and all three run through the same body of water.

What has changed is the reliability of the arrangement. The ocean is warming at a measured rate, marine heatwaves are projected to become the normal condition rather than the exception, and cyclone behaviour over the Arabian Sea has already shifted within a documented window. None of that predicts a particular monsoon or a particular year. It does mean the system that half of India’s sown land relies on is being altered while it is being relied upon. What follows from that, and what a serious national response would look like, is the subject of our article on why India needs an ocean conservation revolution.

Most public conversation about this ocean is about who controls it. Given how much of your rain, food and freight already passes through it, is control the question you would have asked first?