Climate Change and You: Will Indian cities run out of water in a few decades?

Climate Change and You is a fortnightly newsletter written by Bibek Bhattacharya and Sayantan Bera. Subscribe to the newsletter to get it directly in your inbox.

Dear reader,

The story of climate change is, in many ways, the story of water. What do we mean by that? The world is getting hotter because of planet-heating greenhouse gases (GHGs) emitted by humanity’s use of fossil fuels. The effect of this is felt in the different ways that heat affects water, the key to life on the planet. Whether it is rainfall, glaciers, sea levels, the health of forests and ecosystems, or the daily water we need, a heating planet disrupts our relationship with water disastrously. We experienced this disruption in a very intense manner this past month.

At one end of the spectrum was drought, especially the unthinkable horror of a city running out of water. Iran’s capital, Tehran, one of the biggest cities on Earth with a population of over 15 million, is experiencing a severe drought. In fact, the situation is so dire that the Iranian President Masoud Pezeshkian recently warned, “We’ve run short of water. If it doesn’t rain, we in Tehran…must start rationing. Even if we do ration and it still does not rain, then we will have no water at all. They [the citizens] must evacuate Tehran.”

Cities running out of water is a nightmare situation. This is referred to as Day Zero Drought (DZD), with day zero referring to the day when water reservoir levels fall so low that taps run dry. With the rise in droughts due to climate change, more regions of the Earth, especially those like India with intensive irrigation practices, are teetering dangerously on the edge. An important study published in the journal Nature Communications in end-September states that, “Many regions, including major reservoirs, may face high risk of DZD by the 2020s and 2030s…urban populations are especially vulnerable at the 1.5ºC warming level.” The study identifies India as a hotspot for acute water scarcity, largely driven by multi-year droughts.

In fact, India has already experienced DZD-like conditions, like in Chennai in 2019, when the city’s six water reservoirs suffered a calamitous drop following a prolonged period of no rainfall. Bengaluru is increasingly facing a similar situation nearly every year as winter rainfall becomes erratic, leading to droughts. A combination of climate change disruption and chronic poor water management poses a risk to most Indian cities, as Delhi found to its detriment earlier this year.

STATE OF THE CLIMATE

When it rains, it floods

If drought is one side of the coin, the other is devastating floods. And we saw quite a lot of that in our immediate neighbourhood this past month. Through the latter half of November and early December, a combination of tropical cyclones and heavy monsoon rains devastated large parts of Indonesia, Sri Lanka, Thailand, and Malaysia. Nearly 300,000 people have been displaced, and as of the time of writing this newsletter, over 1,750 have been killed in these floods in Indonesia, Thailand, and Sri Lanka.

Even parts of India have not been spared in this winter flood onslaught. Cyclone Ditwah, which devastated Sri Lanka, had weakened considerably by the time it hit south coastal Andhra Pradesh, but it still caused heavy rains and flooding in southern Andhra Pradesh and northern Tamil Nadu. Cities like Nellore and Chennai, too, experienced waterlogging as the cyclone stalled and took a while to weaken further.

The reason for such furious storms year after year—including widespread devastation during the monsoon—has been clearly linked to global warming. One reason is that hotter air can hold more moisture, creating the perfect conditions for sudden, violent cloudbursts. Second, with sea surface temperatures rising to record levels across the Indian Ocean, cyclones are becoming stronger and more frequent as they gather more destructive power from warmer waters.

CLIMATE CHANGE TRACKER

How has global warming affected India?

One interesting thing I’ve observed is that while international reports on the state of climate change appear frequently, to date, there has been just one comprehensive regional report that’s been published on the state of climate in India. That was back in 2020, under the auspices of the ministry of earth sciences. Well, that has changed now, with a new study published in late November titled, A Post-AR6 Update On Observed And Projected Climate Change In India.

Co-authored by scientists Roxy Mathew Koll, Chirag Dhara (who’d been the lead author of the previous study as well), Aditi Deshpande, Padmini Dalpadado and Mandira Singh Shrestha, the aim of the study is to update our understanding of how climate change is affecting India in light of the fact that an entire generation of new climate data has come to light since 2020.

There are several important updates, including the fact that between 2015 and 2024, the average air temperature was 0.89 degrees Celsius hotter than the baseline of 1901-1930. Nearly a degree of warming is less than the global average of 1.42 degrees Celsius, but this has been enough to plunge India into a host of climate-related challenges.

Heat is one of them. The study observes that between 1951 and 2024, the number of warm days has increased by an average of 5-10 days per decade across India. In peninsular and North-East India, this number jumps to 10-15 days per decade. Going by updated climate models, the study finds that in the near future (2025-2054), India will heat up by 1.1 degrees Celsius (under very low global GHG emissions) and 1.3 degrees Celsius (under high global GHG emissions). In the far future (2065-2094), India would heat up between 1.5 degrees Celsius (under zero to low GHG emissions) and a nightmarish 4.1 degrees Celsius in a business-as-usual scenario. “The probability of exceeding observed hottest summers is projected to increase seven-fold in a 2°C warmer world and twenty-fold in a 3°C warmer world compared to the present climate, with Northwest, North Central, Northeast, and parts of the Interior Peninsula being most affected,” the report states.

THE NEWS IN BRIEF

-The world’s megacities are increasingly in Asia and Africa, says this Bloomberg editorial. And it is precisely the regions that are under high risk of dangerous floods as global warming escalates.

-Extreme climate events pose a serious near-term risk to India’s growth story. As this report states, by 2030, up to 4.5% of India’s GDP could decline due to the impact of extreme weather.

-While India is making steady progress in adding renewables capacity, formidable challenges remain in meeting the national goal of 500GW of renewable energy by 2030. Read about them here.

KNOW YOUR JARGON

Overshoot

The recently-concluded COP30 climate summit in Brazil was a damp squib, to say the least. In fact, all it could really achieve was to demonstrate that global multilateralism is still alive, which is a pretty low bar. With the world on track to heat up beyond the 1.5 degree Celsius safety mark earlier than predicted, the final summit agreement contained a line that said that countries were resolved to limit “the magnitude and duration of any temperature overshoot”.

What is this overshoot? Basically, this means that while the stated goal of international climate action is to keep global heating to below 1.5 degrees Celsius by 2100, it is now certain that the world will overshoot this limit in the next few years (the current global average is about 1.4 degrees Celsius). However, if we aggressively reduce our reliance on fossil fuels, it is possible to bring global warming back down to 1.5 °C and below by the end of the century.

The problem is that this is a very big “if”. The longer we don’t act, the greater the concentration of CO2 in the atmosphere will be, and it will get to a point that the world switches over to clean energy, but by then the accumulated CO2 levels are so high that a long period of increased warming will be locked in, one that we and our successive generations will have to suffer. It is all the more necessary to act now.

BOOK OF THE MONTH

Is A River Alive? by Robert Macfarlane

I have written about Robert Macfarlane’s books in this newsletter before, and it gives me great pleasure to recommend Is a River Alive?, the latest by this lyrical nature writer. Macfarlane draws on the long-standing ‘Rights of Nature’ movement that argues that rivers are living beings that should be granted legal personhood and protections. Macfarlane journeys to three river systems in Ecuador, India, and Canada, and charts how all three sustain local communities and wildlife, and how they are, in turn, being threatened by mines, pollution, and dams. What emerges is an important book that shows us the limits of treating the environment as mere economic resources, and recognizing rivers for what they are—fountains of life.

That’s it for me this week at Climate Change and You. Sayantan Bera will be back in a fortnight with the final issue of the year. See you all next year.