14.6 — The Other Limits

Climate change receives most of the attention, and on several measures it is not the most immediate environmental constraint.

A group of Earth system scientists proposed in 2009 a set of planetary boundaries — processes with thresholds beyond which the Earth system may shift into a different state. Their most recent assessments conclude that six of nine have been crossed: climate change, biosphere integrity, land-system change, freshwater, biogeochemical flows of nitrogen and phosphorus, and novel entities meaning synthetic chemicals and plastics.

The framework is contested — the thresholds are uncertain and some are not global in the way the model assumes — and it is a useful organising structure, and this chapter covers the limits that are less discussed.

Water

The most immediate constraint for India and for a large part of the world.

Chapter 1.12 gave the geology. Groundwater is the issue, and the numbers are stark.

India is the world's largest user of groundwater, extracting more than China and the United States combined, overwhelmingly for irrigation.

The northwestern aquifer — Punjab, Haryana, western Uttar Pradesh — is being depleted faster than it recharges, measured directly from space by the GRACE satellites, which detect the change in Earth's gravity field caused by the loss of that mass of water.

Why. Chapter 6.28's Green Revolution package: subsidised or free electricity for pumping, guaranteed procurement of rice and wheat at support prices, and no charge for the water itself. Rice in semi-arid Punjab is agronomically wrong and is sustained entirely by policy.

And the depth of tube wells has increased steadily, which means the energy required to pump rises, which means the subsidy rises, which is a spiral.

What works. Punjab's law requiring rice transplanting to be delayed until the monsoon has arrived, which reduced pumping measurably. Direct benefit transfer instead of free power, which preserves farmer income while creating an incentive to conserve — piloted with mixed results. Micro-irrigation. And crop diversification, which requires changing the procurement system, which is politically very hard.

Peninsular India has the opposite problem (Chapter 1.12): hard rock with little storage, so wells are shallow and fail in drought.

Globally. Around 2 billion people live in countries with high water stress. Major aquifers in the North China Plain, the American High Plains and the Middle East are all in decline.

And the transboundary question. Rivers crossing borders — the Indus, the Ganges, the Brahmaputra, the Nile, the Mekong, the Tigris and Euphrates — are a permanent source of dispute. The Indus Waters Treaty of 1960, brokered by the World Bank, divided the rivers between India and Pakistan and has survived three wars, which makes it one of the more durable water agreements anywhere, and it is under strain.

Soil

Chapter 1.9 established the arithmetic: soil forms at something like a centimetre per century and is lost far faster under cultivation.

The global estimate is that a substantial share of agricultural land is degraded to some degree, through erosion, salinisation, compaction, nutrient depletion and loss of organic matter.

India's specific position. Very large areas are affected by water erosion, and salinisation affects irrigated land, which is Chapter 3.7's Mesopotamian problem recurring (Chapter 4.1). The ravine lands of the Chambal are the visible extreme.

What causes it. Ploughing exposes bare soil. Removal of crop residues rather than returning them. Over-grazing. Deforestation of slopes. And the replacement of organic inputs with chemical fertiliser alone, which supplies nutrients and not the organic matter that holds soil structure together.

What works. Reduced tillage. Cover crops. Contour bunding and terracing. Returning residues. Agroforestry. And the restoration of degraded land, which has been done at large scale — the Loess Plateau restoration in China is the most-cited case, and India's watershed development programmes have produced measurable results where they were locally managed.

Nitrogen and phosphorus

The least discussed and, on the planetary boundaries assessment, the most exceeded.

Chapter 9.5 mentioned the Haber-Bosch process. It fixes atmospheric nitrogen into ammonia for fertiliser, and it is estimated to sustain a very large share of the world's current population — commonly stated as around half. It is arguably the most consequential chemical process ever industrialised.

And it has doubled the amount of reactive nitrogen circulating in the biosphere.

What the excess does. Nitrogen not taken up by crops runs off into rivers and coastal waters, where it fertilises algal blooms, which decompose and consume the dissolved oxygen, producing dead zones where nothing that needs oxygen can live. The Gulf of Mexico dead zone, fed by the Mississippi, covers thousands of square kilometres each summer. The Baltic and the Bay of Bengal have large hypoxic areas.

Nitrous oxide emissions from fertilised soil (Chapter 14.1).

And nitrate contamination of drinking water.

India's fertiliser subsidy is heavily skewed toward urea, which is nitrogen, and the result is a badly unbalanced nitrogen-phosphorus-potassium ratio in Indian soils, with over-application of nitrogen and under-application of the others. This is a subsidy design problem producing an agronomic and environmental problem, and it has been identified repeatedly and not corrected because the subsidy is politically protected.

Phosphorus is a separate concern. It is mined from a small number of deposits, with Morocco and Western Sahara holding the large majority of known reserves. There is no substitute — phosphorus is an element, and every living thing needs it. Estimates of how long reserves last vary widely and the concentration is a genuine strategic vulnerability.

Biodiversity

Chapter 1.10 covered the extinction question and here are the mechanisms.

In order of current impact. Habitat loss, principally agricultural expansion — this is by a wide margin the largest driver. Direct exploitation, meaning hunting and fishing. Invasive species. Pollution. And climate change, which is currently fifth and rising.

The measurable indicators. Vertebrate population sizes have declined substantially over recent decades on the most-cited index, though that index's methodology has been criticised for being skewed by a small number of severely declining populations. Insect biomass declines have been recorded in several long-running studies. Around a million species are assessed as threatened.

Wild mammal biomass is now a small fraction of the total mammal biomass on Earth; humans and livestock make up the great majority.

Fisheries. A large share of assessed stocks are fished at or beyond sustainable limits. And where management has been imposed — catch limits, protected areas, gear restrictions — stocks have recovered, which is the encouraging finding: fisheries respond to management faster than most systems.

India's position. Four global biodiversity hotspots — the Western Ghats, the Eastern Himalaya, the Indo-Burma region and the Nicobar islands. Tiger numbers have risen substantially under Project Tiger from a low point, which is a genuine conservation success. And the wider picture is of habitat fragmentation and human-wildlife conflict rising as land use intensifies.

Plastics and chemicals

The "novel entities" boundary.

Plastic production has grown enormously and a small fraction is recycled. Most is landfilled, burned or leaks into the environment.

Microplastics have been found in soil, in rain, in the deep ocean, in Arctic ice, and in human blood, placenta and lung tissue. The health effects are not established; the ubiquity is.

And recycling has been oversold. Most plastic types are not economically recyclable, and industry documents from the 1980s and 90s show awareness that recycling would not work at scale alongside its promotion as the solution — which is Chapter 14.2's manufactured-doubt pattern in another sector.

What actually reduces plastic waste, on the evidence: reducing production, extended producer responsibility making manufacturers pay for disposal, deposit-return schemes which achieve very high return rates where implemented, and bans on specific hard-to-manage items.

Persistent organic pollutants and PFAS — so-called forever chemicals, which do not break down and which are now detected almost universally in human blood — are a category where regulation has lagged production by decades.

Air pollution

The environmental problem that kills the most people now, by a wide margin.

Estimates attribute several million premature deaths a year to ambient and household air pollution.

India carries a large share of it. Northern Indian cities regularly record among the world's highest particulate concentrations, particularly in winter, for the reasons in Chapter 2.2: a temperature inversion trapping emissions under a lid, weak winds, and sources including vehicles, industry, construction dust, waste burning, household fuel and crop residue burning.

Estimates of life expectancy loss in the most affected areas run to several years.

And it is more tractable than climate, because the sources are local and the benefits of action are local and immediate. Beijing's improvement over the last decade demonstrates that it can be done, at cost and with sustained enforcement.

The framing

Two observations that hold across all of these.

Most are commons problems. A resource with no owner, or with many users and no effective rules, gets over-used — Garrett Hardin's tragedy of the commons.

And Hardin's conclusion was wrong in an important way, which Elinor Ostrom demonstrated and won a Nobel Prize for. She documented commons that have been managed sustainably for centuries by their users — irrigation systems in Spain and Nepal, forests in Japan and Switzerland, fisheries in Turkey — without either privatisation or state control.

Her conditions for it to work: clearly defined boundaries and membership; rules matched to local conditions; those affected participate in making the rules; monitoring by people accountable to the users; graduated sanctions; accessible conflict resolution; recognition by higher authorities of the right to organise; and nested layers for larger systems.

This is the most useful finding in environmental governance and it applies directly: India's traditional tank irrigation systems and community forest management, where they have survived, are examples, and their decline under centralised state management is documented.

And the second observation. Almost every one of these limits is currently subsidised in the wrong direction. Free power for groundwater pumping. Fertiliser subsidies skewed to nitrogen. Fossil fuel subsidies globally in the hundreds of billions of dollars annually. Fishing fleet subsidies. Removing perverse subsidies is the cheapest environmental policy available and is politically the hardest, because every subsidy has a constituency that knows exactly what it would lose.

Where this shows up in your life

The water in your tap and the depth of the well it came from. The air you breathe, and the years it may be costing. The nitrogen in the food you eat and the dead zone off the coast.

And the honest closing point of this Part. Climate is the most discussed and is not obviously the most urgent for a person living in northern India today, where air pollution is measurably shortening lives now and groundwater depletion will constrain agriculture within decades.

The useful mental model is that these are not separate crises. They share drivers — land use, energy, agriculture, consumption — and they share solutions. Reducing fossil fuel combustion improves air quality and climate. Restoring soil sequesters carbon and holds water. Efficient irrigation saves water and energy. Almost every intervention in this Part does more than one thing, which is the strongest argument for acting on them together.

What the next Part covers

Part 15 is lighter and it is not trivial. Where calendars came from and why the year is the shape it is. India's festivals and why the same religion is celebrated so differently in different regions. The festivals and holidays of the rest of the world. Why the working week is five days and the weekend two, why retirement is around sixty, and how the shape of an ordinary life was constructed. Where the world's languages came from and why some are dying. And how the world's food was assembled from a set of crops that mostly did not grow where they are now eaten.