Human Population and the Environment

World population passed 8 billion in November 2022, after taking most of human history to reach 1 billion and just over two centuries to reach 8. Growth is now slowing in most countries, but unevenly.

• India overtook China in 2023 as the most populous country; UN estimates put it at roughly 1.46 to 1.48 billion today, with a total fertility rate of about 1.9 children per woman, below the replacement level of about 2.1.
• China and several countries (Japan, South Korea) have very low fertility and shrinking or ageing populations.
• Many African countries still have high fertility and fast growth.

Variation exists within India: in the National Family Health Survey 2019–21, Tamil Nadu and Kerala had fertility of about 1.8, below replacement, while Bihar was about 3.0. Population is projected to keep growing for some decades, then stabilise and decline.

“Population explosion” describes the rapid growth that followed falling death rates through better health and food. More people means more demand for land, food, water and energy, and more waste. But numbers alone do not tell the story.

A person in a high-income country can use many times the resources of a person in a low-income one, and studies suggest the richest tenth of the world’s people cause around half of carbon emissions. Meanwhile, poverty itself forces people to over-use local resources such as firewood and grazing land. So both consumption in rich societies and poverty in poor ones need attention.

Demographic transition

As societies develop, they move from high birth and death rates, to falling death rates and fast growth, to falling birth rates and slower growth, and finally to low birth and death rates. Education of girls, health care and income are among the strongest drivers of lower fertility.

India was among the first countries to launch a national family planning programme (1952). It was renamed the Family Welfare Programme in 1977 to include maternal and child health, and the National Population Policy (2000) set out goals for reproductive health, reduced fertility and child survival. Today the approach stresses voluntary choice, access to contraception and health services, education for girls and later marriage, rather than targets or coercion.

Roughly two in five Indians now live in towns and cities, and the share is rising. Urban growth concentrates demand for water, housing, transport and energy and produces waste and pollution, but well-planned cities can use resources more efficiently than scattered settlement. Environmental stress (drought, floods, loss of land) is also a driver of migration.

The One Health approach recognises that human, animal and environmental health are linked, as in diseases that pass from animals to humans (Nipah virus in Kerala, COVID-19).

HIV (human immunodeficiency virus) attacks the body’s immune system and, untreated, leads to AIDS. It spreads through unprotected sex, infected blood and needles, and from mother to child during pregnancy, birth or breastfeeding. It does not spread through casual contact such as touching, sharing food or mosquitoes.

• Prevention: safe sex, tested blood, sterile needles, treating pregnant women with antiretroviral drugs, education
• Treatment: antiretroviral therapy (ART) lets people with HIV live long and healthy lives and greatly reduces transmission
• India: adult prevalence is low, about 0.2%, thanks to the National AIDS Control Programme. The HIV and AIDS (Prevention and Control) Act, 2017 protects people from discrimination.

The link to this course is social: poverty, migration for work, lack of information and stigma raise vulnerability, which is why awareness and compassion matter as much as medicine.

• Arsenic in groundwater (West Bengal and Bangladesh): millions drank contaminated tubewell water for years
• Household smoke: cooking on biomass is among the largest sources of indoor air pollution for rural women and children
• Heat waves in India: repeated, deadly events have led cities to prepare heat action plans

The Universal Declaration of Human Rights (1948) affirms rights to life, health and an adequate standard of living, all of which depend on a healthy environment. Indian courts have read a right to a clean environment into Article 21 of the Constitution. Indigenous and forest communities also hold rights over their lands and resources (Forest Rights Act, 2006).

Value education builds attitudes that sustain the environment: respect for all life, care for common resources, fairness to future generations, simplicity, and responsibility. Many Indian traditions treat rivers, trees and the Earth as sacred, and schools and colleges can turn such values into daily habits through eco-clubs, campus audits and service projects.

• Women as environmental managers: women in many communities gather fuel, fodder and water, and lead movements such as Chipko in India and the Green Belt Movement in Kenya, founded by Wangari Maathai, who won the Nobel Peace Prize in 2004.
• Burdens: time spent collecting water and fuel, and exposure to cooking smoke, cut into education and health.
• Children: are especially vulnerable to polluted air and water, lead and malnutrition. Programmes such as the Integrated Child Development Services and POSHAN Abhiyaan address nutrition, and safe water and sanitation protect child health.

• Remote sensing and GIS: satellites map forests, water and land use (India’s Bhuvan platform), and the Forest Survey of India issues forest-fire alerts
• Monitoring: real-time air-quality sensors and public apps such as CPCB’s SAMEER
• Forecasting and warning: weather, flood and cyclone prediction
• Citizen science: apps like eBird and iNaturalist let anyone record biodiversity
• Health: telemedicine (such as eSanjeevani), disease tracking and online health information

Technology has costs too: electronic waste, data-centre energy use, and the digital divide that leaves poorer communities behind.