Episode 59: This Week in India's Science: 14 July 2025

Host: Subhra Priyadarshini; Sound editing: Prince George

*****

Welcome back to This Week in India’s Science. I’m Subhra Priyadarshini, and in this episode:

A climate signal from Earth to Moon during the COVID lockdowns,

Flood secrets buried in Maharashtra’s ancient reservoirs,

The shape-shifting protein behind oral cancer’s aggression,

And the race to save a 450-million-year-old pre-dinosaur creature from extinction.

Let’s begin.

*****

Five years ago, the world fell still. Skies cleared, factories paused, and for the first time in decades, the Earth radiated less heat. But what if that pause was felt on the Moon?

New research from India’s Physical Research Laboratory has found that during the peak COVID-19 lockdown months of April and May 2020, the Moon’s night-time surface temperatures dropped by nearly 8 to 10 degrees Celsius.

K. Durga Prasad: We all know that the global COVID-19 lockdown reduced atmospheric pollution and that led to a measurable decline in terrestrial radiation. Our analysis shows that the Moon’s night-side surface temperatures dropped due to this change in Earth's radiation. And this reveals that the Moon is sensitive to even subtle changes in Earth’s radiative output.

Physicist K. Durga Prasad at the Physical Research Laboratory in Ahmedabad, Gujarat.

Earth emits heat to space — known as terrestrial radiation. Some of it reaches the Moon. But during lockdown, with less pollution and fewer clouds, that heat was dramatically reduced. Durga Prasad and his colleagues used NASA’s Diviner Lunar Radiometer data from 2017 to 2023 to detect a clear dip in lunar temperature only during the strict lockdown.

Sceptics remain cautious, pointing to the small effect Earth’s heat might actually have on the Moon. This week, Biplab Das reports for Nature India that this study makes a provocative case: that planetary-scale change on Earth leaves a trace far beyond.

*****

Across Maharashtra’s Bhima basin, small reservoirs known as talavs — some built as early as the 16th century — hold memories of ancient climate trauma.

A new study led by Atreyee Bhattacharya, a geoscientist at the University of Colorado Boulder, found that these reservoirs recorded deluges tied to El Niño events, when dry spells suddenly gave way to intense rainstorms.

Atreyee Bhattacharya: This is the first time we have linked local climate events and associated disasters in India's semi-arid interiors to El-Niño Southern oscillation (ENSO) variability, which is very important for Indian summer monsoons.

In the Matwali talav, a thick layer of coarse sediment from 1988–89, which was a strong El Niño year, shows floodwaters scoured the land, dumped soil, and overwhelmed the reservoir. In some places, sedimentation increased up to 30 times the usual rate.

Worse still, modern land use like farming on dry beds and grazing on embankments destabilised the terrain. When the rains came, the land couldn’t cope.

The researchers say there are fewer rainy days now, but the rainfall is more intense. These ageing structures were not built for this, they say.

Sediment core records are vital tools. The landscape model suggests that rainfall peaks correspond with sediment discharge. While human activity may play a role, rainfall is the main driver in these sites.

As India faces increasing climate extremes, these buried stories are warnings from the past and blueprints for resilience. Read the story by Sahana Ghosh on Nature India this week.

*****

On to the next story this week: Oral cancer is one of India’s deadliest cancers. Now, researchers at the BRIC–National Institute of Biomedical Genomics in Kalyani, West Bengal, have uncovered a molecular accomplice behind its resilience.

At the centre of the discovery is a receptor called Tie2, found in surrounding fibroblast cells — not the cancer cells themselves. These fibroblasts, activated by Tie2, reprogramme nearby cancer cells into an embryonic-like state — harder to kill and more prone to spread.

Sandeep Singh: You see, what we found is that some support cells near oral cancer cells can actually help the tumour grow and spread. These cells send signals that push the cancer into a more aggressive, harder-to-treat form . But the good news is — if we block those signals, we might actually be able to stop the cancer from getting stronger. This could open the door to more targeted treatments of oral cancer.

Sandeep Singh from BRIC-NIBMG there.

Using sequencing and tumour growth assays in mice and zebrafish, the team found that blocking Tie2 in these fibroblasts reversed the cancer’s ability to invade.

*****

Older than dinosaurs and largely unchanged for 450 million years, the horseshoe crab is one of Earth’s most ancient survivors. But now, it’s disappearing fast from India’s eastern coast.

Two native species—Tachypleus gigas and Carcinoscorpius rotundicauda—have declined by over 70% in two decades, says a new report from Fakir Mohan University’s conservation centre in Balasore, Odisha.

Bharat Bhusan Patnaik: These creatures have survived asteroid strikes and ice ages — but they may not survive us. We’re trying to turn that around with science and local knowledge. The horseshoe crab's blood helps make our medicines safe — vaccines, drugs, implants, you name it. Without it, modern healthcare would look very different. So protecting the species is also about safeguarding a lifeline for human health.

Bharat Bhusan Patnaik from the Center for Research and Conservation of Indian Horseshoe Crabs (CRCIHSC) in Balasore, Odisha.

These marine arthropods also sustain intertidal food webs, including endangered shorebirds. But pollution, ghost nets, habitat loss, and urban expansion have decimated their breeding grounds. Many traditional nesting sites have disappeared. Rivers now bring wastewater, not nutrients.

Surveys by IISER Kolkata’s Punyasloke Bhadury warn that numbers may be even lower now, especially in Odisha and the Sundarban.

To rescue the species, scientists are mapping breeding grounds, launching tagging and rehabilitation efforts, and proposing AI-based monitoring tools. They also call for citizen science.

Bharat Bhusan Patnaik: If people along the coast start reporting sightings or rescues — or even just sending photos — we can build a real-time map of where these crabs are hanging on. Conservation always doesn’t need big budgets, it can start with local eyes or local action.

*****

That’s it This Week in India’s Science. Subscribe, share, and listen to the Nature India podcast on wherever you get your podcasts from. Until next time, I am Subhra Priyadarshini.