By Daniel Lawler

The world’s largest whale graveyard has been discovered at the bottom of the Indian Ocean by Chinese scientists, who found that the vast expanse of both new and ancient carcasses supports huge communities of deep-sea life.

It is also the deepest and oldest known whale graveyard on Earth, according to research published in the journal Nature on Wednesday, with some fossils dating back 5.3 million years.

From inside a small submersible, the Chinese researchers saw an array of strange animals — many believed to be new to science — living off the whale carcasses.

A new, though extinct, species of whale was also identified among the nearly 500 skeletons found up to 7,000 metres deep along a 1,200-kilometre corridor of bones in the Indian Ocean west of Australia.

Lead study author Xiaotong Peng of the Chinese Academy of Sciences told AFP that the researchers were “astonished” when the scale of their discovery became clear.

It was known that when whales die and drop to the seafloor, their sunken bodies — called “whale falls” — provide a source of food to bottom-dwelling creatures.

“But discovering a necropolis of this scale was completely unexpected: the size of distribution, the depth and the age range were far beyond anything we had imagined,” Peng said.

The researchers had several theories for why so many whales died in this particular corridor, including that it is a popular foraging area and has a V-shaped trench that funnels carcasses to the ocean’s floor.

‘Truly incredible experience’

For the discovery, the Fendouzhe submersible carried out 32 dives in 2023 — though what it found was only revealed in Nature on Wednesday.

The sub took up to three people on the dives, collecting the fossil samples using robotic arms.

Study co-author Zhou Peng said witnessing the whale graveyard “was a truly incredible experience”.

“The vibrant ecosystems we saw offered a completely different perspective on this otherwise dark and cold ocean floor.”

Among the animals they discovered living off the carcasses were jellyfish, worms, snails, crustaceans, brittle stars and molluscs called bivalves.

Extrapolating from the number of bones they found, most of which were from beaked whales, the scientists estimated there could be more than 10 million carcasses across the area called the Diamantina Zone.

The soft tissue and lipids inside those many carcasses “translates to roughly 6.7 million tonnes of sequestered carbon,” Xiaotong Peng said.

This provides an immense source of sustenance for animals, similar to how hydrothermal vents create their own ecosystems on the ocean floor.

Some of the animals seen by the scientists also live in hydrothermal vents and cold seeps, suggesting whale carcasses could help connect these deep-sea communities to each other.

While this is by far the largest whale graveyard yet found, fossils found during trawling suggest there could be others off South Africa, the Iberian peninsula and the Crozet islands, according to the study.

‘More blockbusters to come’?

University of Hawaii oceanographer Craig Smith, who discovered the first whale fall in 1987 but was not involved in the new research, told AFP it was “extremely exciting”.

“The vast number of fossil whale falls documented, including a new species of beaked whale, is truly amazing and is of major importance to understanding whale evolution and whale distributions over geologic time,” he said.

Whale fall researcher Amy Baco-Taylor at Florida State University told AFP the “remarkable discovery” would “likely provide many new insights”.

“It does seem very strange” that so many whales died in this area, Baco-Taylor admitted, adding that “we don’t know enough about whale consciousness”.

US palaeontologist Stephen Godfrey compared the “truly unique discovery” to past major underwater finds, such as when scientists first identified hydrothermal vents teeming with life on the ocean floor in 1977.

He called for future submersible voyages to find more whale graveyards across the world.

This discovery “reminded me of a trailer for the first in a series of epic movies”, Godfrey commented in a linked Nature paper.

“I hope that there will be many more of these blockbusters to come.”

Editors’ Vox is a blog from AGU’s Publications Department.

Mesoscale and submesoscale ocean processes influence ocean circulation, air-sea fluxes, ecosystem variability, and transport of materials. A new article in Reviews of Geophysics examines how these fine-scale processes shape the Indian Ocean, an ocean basin with unique monsoon behavior and a disproportionate impact on global climate. Here, we asked the authors to explain what mesoscale and submesoscale processes are, the techniques and challenges of observing and modeling fine-scale processes, and how biogeochemical cycles and climate change interact with these processes.

In simple terms, what are mesoscale and submesoscale processes?

Mesoscale processes pertain to oceanic features such as eddies and fronts, which
typically span a range of approximately 10 to 100 kilometers and can persist from
weeks to months. Submesoscale processes are of an even smaller scale, ranging
between approximately 100 meters and 10 kilometers, and evolve rapidly within a time frame of hours to days. These encompass sharp fronts, filaments, and small vortices.

Mesoscale processes account for more than 80% of the total kinetic energy. Submesoscale motions are of particular significance as they generate robust vertical movements that establish a connection between the surface ocean and deeper layers. As elaborated in our review, mesoscale and submesoscale processes function as a crucial link between large-scale ocean circulation and small-scale turbulence, facilitating the transfer of energy across different scales and regulating the distribution of heat, salt, and nutrients throughout the ocean.

Why is it important to understand how fine-scale processes operate in the Indian Ocean?

The Indian Ocean has a disproportionate influence on global climate. It absorbs over a quarter of the ocean’s net heat gain and directly affects the environment and food security of nearly one-third of the world’s population. Unlike other ocean basins, the Indian Ocean is uniquely shaped by seasonally reversing monsoon winds and is strongly coupled with climate modes like the Indian Ocean Dipole and the Madden- Julian Oscillation. Mesoscale and submesoscale variability in this region modulates biogeochemical cycles, air-sea fluxes, and even large-scale energy balance. As our review highlights, understanding these fine-scale dynamics is essential for improving predictions of monsoon rainfall, tropical cyclone behavior, and long-term climate change.

How do scientists study mesoscale and submesoscale ocean processes?

Scientists employ a combination of field measurements, satellite observations, and numerical models, all of which were summarized in our review. In-situ observations serve as the foundation for mesoscale and submesoscale processes in the ocean. They encompass research cruises, moored arrays such as the RAMA network, Argo profiling floats, and autonomous platforms. The in-situ observations capture the three-dimensional structures and multiple variables during mesoscale and submesoscale processes.

Satellite altimetry has long been the principal tool for observing mesoscale eddies. However, the newly launched Surface Water and Ocean Topography (SWOT) mission is revolutionary, as it offers sea surface height measurements at an unprecedented resolution, enabling the direct observation of submesoscale features for the first time.

High-resolution regional models with grid spacings of a few kilometers or less enable researchers to simulate these processes and test dynamical theories under controlled conditions.

What are some of the challenges in observing and modeling these processes?

In our review paper, we tackled the challenges in observations by adhering to four principles, namely high-resolution (more observations in a relatively small region), synchrony (observations conducted at the same time), persistence (observations for a long time), and interdisciplinary (observations of multiple ocean properties). These principles are anticipated to offer valuable guidance for future observational endeavors to surmount the corresponding challenges.

Modeling also poses difficulties. Even state-of-the-art climate models are unable to explicitly resolve submesoscale processes. Consequently, their effects have to be approximated via parameterizations. The development of accurate parameterizations continues to be an active area of research. Moreover, as the model resolution improves, the widely employed hydrostatic approximation may lose its validity, necessitating more intricate non-hydrostatic formulations. Data assimilation for such rapidly evolving features presents a particularly arduous challenge.

How do fine-scale processes interact with biogeochemical cycles in the Indian Ocean?

Mesoscale and submesoscale motions exert a strong regulatory influence on biogeochemical cycling through the control of nutrient supply to the sunlit upper ocean. Cyclonic eddies elevate nutrient-rich deep waters into the euphotic zone, thereby promoting phytoplankton blooms. In contrast, anticyclonic eddies typically suppress surface productivity by deepening the mixed layer.

In the Arabian Sea, eddies and filaments can contribute up to 70% of the nutrients that support the monsoon-driven biological bloom. These fine-scale dynamics also have an impact on carbon dioxide exchange; mesoscale variability accounts for approximately 40% of the CO₂ flux variability in the western Arabian Sea. Moreover, eddies modulate oxygen minimum zones in the Arabian Sea and Bay of Bengal, where low oxygen levels have a profound effect on marine ecosystems.

How is climate change expected to influence these fine-scale processes in the Indian Ocean?

With the continuous progression of climate change, alterations in upper-ocean stratification, propelled by warming and modified freshwater inputs, are anticipated to transform the conditions giving rise to fine-scale instabilities. High-resolution climate model simulations suggest that in a warming global scenario, the eddy-active region associated with the Agulhas Current system may shift westward and poleward. This shift is correlated with the intensification of Agulhas leakage, which refers to the transport of warm Indian Ocean water into the Atlantic. These changes could exert far-reaching effects on global ocean circulation.

Moreover, warming is augmenting the frequency and intensity of marine heatwaves in the Indian Ocean. These heatwaves disrupt vertical mixing and nutrient supply, thereby having cascading impacts on biological productivity. Nevertheless, substantial uncertainties persist in quantifying these long-term responses.

In general, there are two-way interactions between climate change and fine-scale processes. Alterations in one component will induce changes in the other, and the former will be subject to feedback from the latter.

What are the remaining questions or knowledge gaps where additional research is needed?

Our review reveals several key priorities. In the short term, specialized multi-scale observational campaigns are acutely required, especially in regions with insufficient sampling, to capture the three-dimensional structure and rapid evolution of submesoscale features. Additionally, a more in-depth understanding is needed regarding how eddies interact with barrier layers—regions characterized by strong salinity stratification that are unique to the northern Indian Ocean—and how these interactions regulate air-sea fluxes and marine heatwaves.

Longer-term challenges encompass integrating fine-scale dynamics into climate models and refining submesoscale parameterizations. Emerging tools from artificial intelligence and machine learning hold potential for representing unresolved processes and enhancing data assimilation. Finally, considering the logistical and financial requirements of fine-scale ocean research, sustained international collaboration will be indispensable.

—Lei Zhou (zhoulei1588@sjtu.edu.cn, 0000-0002-0433-3991) Shanghai Jiao Tong University, China; Dongxiao Wang (dxwang@mail.sysu.edu.cn, 0000-0001-8778-2188) Sun Yat-Sen University School of Marine Sciences, South China Sea Institute of Oceanology, China; Lin Wang (wanglin58@mail.sysu.edu.cn, 0009-0003-1062-5207) Sun Yat-Sen University, China; and Chunhua Qiu (qiuchh3@mail.sysu.edu.cn, 0000-0001-9684-6067)  Sun Yat-sen University School of Marine Sciences, China

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Zhou, L., D. Wang, L. Wang, and C. Qiu (2026), Small-scale Indian Ocean dynamics underpin marine ecology and climate, Eos, 107, https://doi.org/10.1029/2026EO265025. Published on 4 June 2026.

This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s).

Text © 2026. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: AGU Advances

The Indian monsoon has shifted over the past quarter century. Northwest India now receives substantially more rain than it once did, while a lack of rain sends the Indo-Gangetic Plain toward drought.

More than a billion people rely on the monsoon to confer economic stability across southern Asia; further changes to this weather system could lead to widespread hardship. Scientists have struggled to predict how this weather pattern will change moving forward because commonly used climate models fail to capture changes to the monsoon that have already occurred.

Mahendra et al. suggest that models do not adequately represent either changes in the temperature of the Atlantic Ocean or how those temperature changes are linked to weather patterns around the rest of the globe. As a result, the coupled models tend to fail to predict this monsoon shift.

Specifically, current climate models lack the ability to incorporate information about the cold blob, a patch of cold water off the south of Greenland. When the researchers added the cold blob to climate model results, they found that it can alter the jet stream in a way that makes it pull moisture toward northwest India while also preventing storm systems from forming elsewhere. This is exactly the type of shift that has been observed in monsoon patterns. When a large-scale wind pattern prevents the formation of smaller-scale weather patterns in this way, it is called a barotropic governor mechanism.

This barotropic governor mechanism also explains why midlatitudes around the globe have observed more storm activity in recent years. The results highlight the importance of connecting processes from disparate parts of the globe when formulating climate models, the authors write. (AGU Advances, https://doi.org/10.1029/2025AV002173, 2026)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2026), The surprising link between a cold blob and the Indian monsoon, Eos, 107, https://doi.org/10.1029/2026EO260177. Published on 1 June 2026.

Text © 2026. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.