The term environment is very familiar and has an extensive and comprehensive definition, implication and interpretation. Many people decipher and associate the environment with nature, natural landscape, and non-human characteristics. Some people nearly relate and pertain to the environment with human elements, whereas some consider the term environment related to agriculture and the rural landscape.

Thus, the term environment is associated with diverse and myriad images and manifestations of the environment. The word environment has emerged from the French word “environs” which denotes 'surround'. The term environment can be understood as the interaction between living ( human phenomena) and non-living (non-human phenomena) entities and the effects and aftermath of this interaction on the human lifestyle.

Environment influences human lifestyle in numerous ways. It offers foison renewable and nonrenewable resources like iron, gold, wood etc for production and apparently, it sustains human life by furnishing genetic and biodiversity. Besides all this Environment enhances and enriches the quality of life by bestowing the bounties of rivers, deserts, forests or mountains which augments the quality of life.

Abiotic and Biotic Environment

The working and the balance within the environment is maintained and sustained through the intricate interaction between abiotic and biotic components present in the environment. Let's contemplate the biotic and abiotic components of the environment.

Abiotic Component (Non-Living Components of Environment)

• Abiotic components are non-living components of nature that affect and influence the growth, development, survival and reproduction of the existing organism. For eg sunlight, air, rain, water resources etc.
• The abiotic components present in nature differ on the ground of a varied ecosystem. Air (oxygen), an abiotic factor plays a vital role in the survival of humans on land, whereas rainfall is imperative for the tropical forest ecosystem.

Biotic Component (Living Components of Environment)

• The biotic component of the environment is considered as the living part of the ecosystem which includes the manufacturers, consumers and the decomposers which shape the ecosystem. For eg plants, bacteria, animals or other living entities.
• Biotic factors define the nature of the ecosystem as it is liable for capturing and grasping the energy and converting it into the organic compound and at the same time it is responsible for the spreading of disease and plagues.

Division of Environment

The environment is divided into four components- lithosphere, atmosphere, hydrosphere and biosphere.

Division of Environment: Lithosphere

• The lithosphere is the external sphere or the exterior part of the earth and consists of the crust and the upper layer of the mantle.
• The lithosphere holds a significant position in the environment as it is that area where living organisms inhabit and live upon.
• The lithosphere is the source of the derivation of all resources, reserves and is prosperous in elements like iron, copper, gold, aluminium, calcium, copper, which helps humans to formulate and develop tools and use them for their necessity.
• Due to the interaction between living entities and the lithosphere, a huge amount of organic compounds are buried and are deposited in the crust for many years.
• As a result, this organic compound is transformed into oil, coal and natural gas which are considered beneficial resources for humans.

Division of Environment: Hydrosphere

• The aggregate amount of water present on the planet is termed as the component of the hydrosphere, whether it is the water present on the surface, in the air or underground.
• The major significance of the hydrosphere is that it sustains and nourishes numerous life forms as the cells present in a living organism requires 75% of water for the proper functioning of the body.

• The hydrosphere is also important for many plants and animals as it provides them with a place to live in. Gases like carbon dioxide and oxygen are handily dissolved in water and hence sustains and nurtures life in the water.
• Hydrosphere also enables us to regulate the temperature on the planet.

Division of Environment: Atmosphere

• The atmosphere is that layer of the earth that comprises a mixture of gases like carbon dioxide, oxygen and nitrogen.
• These gases encircle the earth in a form of a layer and this layer is known as the atmosphere. This layer of gases along with the water vapour present in the atmosphere helps to sustain life on the earth.
• Besides supporting life on the earth, the atmosphere is also crucial for the water cycle and for moderating and maintaining the temperature on the planet. It also acts as a barrier and prevents UV rays from entering the earth.
• Gases present in the atmosphere help the sound to travel from the place of origin to other places. Without the presence of gases, the sound would not be able to travel and thus, the earth would become a silent planet.

Division of Environment: Biosphere

• The biosphere is also known as the ecosphere, and it is considered as the whole sum of all ecosystems. The biosphere supports life and stimulates the interaction between the living and non-living entities.
• The biosphere stimulates the production and the generation of oxygen and carbon dioxide through the process of photosynthesis.
• The biosphere also supports and encourages the cycle of decomposition through which toxic and other harmful substances are expelled and eliminated from the earth.

Ecosystem

The ecosystem is considered as that area where living (biotic) and non-living (abiotic) entities interact and work jointly to maintain and sustain life on earth. In other words, the ecosystem can be defined as a row of interactions and interdependencies between the organism and its surroundings. Mainly the ecosystem deviates into- terrestrial ecosystem and aquatic ecosystem.

Terrestrial ecosystem

The terrestrial ecosystem is considered as the land-based ecosystem where the living organism(biotic entities) interact with the non-living organism (abiotic components) to maintain and stimulate life on the planet. The terrestrial ecosystem is classified as follows-

• Forest ecosystem
• Grassland ecosystem
• Tundra ecosystem
• Desert ecosystem

Aquatic Ecosystem

The aquatic ecosystem comprises oceans, rivers, seas, streams, lakes etc. The organisms living in an aquatic ecosystem depend upon water for their survival. For eg fish, plants and other microorganisms. The aquatic ecosystem is also divided into - freshwater ecosystem and the marine ecosystem.

FAQs 

Question: What topics are typically covered under environment notes for UPSC prelims?

Question: Why is the environment section important for UPSC prelims?

Question: What are the key international environmental agreements relevant for UPSC preparation?

Question: How can one effectively prepare for the environment section in UPSC prelims?

Question: Are environmental laws and policies important for UPSC prelims?

MCQs 

1. The Paris Agreement primarily focuses on:

A) Promoting international trade

B) Reducing greenhouse gas emissions

C) Increasing agricultural productivity

D) Banning nuclear weapons

2. The Convention on Biological Diversity (CBD) was signed during which summit?

A) Kyoto Protocol Summit

B) Rio Earth Summit, 1992

C) Montreal Protocol Summit

D) Paris Climate Summit

3. What is the primary aim of the Ramsar Convention?

A) Protection of deserts

B) Conservation of wetlands

C) Promotion of marine biodiversity

D) Combating desertification

4. Which act governs environmental impact assessments (EIA) in India?

A) Wildlife Protection Act

B) Environment Protection Act, 1986

C) Forest Conservation Act

D) Water Act, 1974

5. The Kyoto Protocol is associated with:

A) Nuclear disarmament

B) Reducing ozone depletion

C) Binding targets for greenhouse gas emissions reductions

D) Protecting endangered species

GS Mains Questions and Model Answers

Q1: Explain the significance of biodiversity conservation in the context of sustainable development.

Answer: Biodiversity conservation is crucial for sustainable development because it ensures the health and stability of ecosystems, which provide essential services like clean air, water, pollination, and climate regulation. Healthy ecosystems contribute to food security, livelihoods, and economic resilience, especially for vulnerable communities. Conservation efforts, including protecting wildlife habitats, regulating resource extraction, and promoting sustainable agricultural practices, help maintain ecological balance and prevent species extinction. Biodiversity also holds cultural, aesthetic, and recreational value, contributing to human well-being. Sustainable development policies must therefore integrate biodiversity conservation to address environmental challenges and create a balanced approach to growth and resource management.

Q2: Discuss the role of international environmental agreements in addressing global environmental challenges.

Answer: International environmental agreements play a vital role in addressing global environmental challenges by fostering cooperation, setting global standards, and mobilizing collective action. Treaties like the Paris Agreement, Kyoto Protocol, and Convention on Biological Diversity (CBD) establish frameworks for mitigating climate change, conserving biodiversity, and protecting ecosystems. These agreements facilitate information sharing, technological cooperation, and financial support for countries to achieve environmental targets. By holding nations accountable for their environmental commitments, such agreements drive policy changes, encourage sustainable practices, and help mitigate cross-border environmental issues. However, challenges like enforcement, compliance, and differing national priorities must be addressed to ensure their effectiveness.

Q3: Analyze the effectiveness of India’s environmental laws in protecting its natural resources.

Answer: India has enacted various environmental laws to protect its natural resources, including the Environment Protection Act, Forest Conservation Act, and Wildlife Protection Act. These laws provide a legal framework for regulating activities that impact the environment, promoting conservation, and preventing exploitation. They mandate environmental impact assessments, regulate forest clearances, and protect wildlife habitats. While these laws have achieved notable success in raising awareness, controlling pollution, and conserving biodiversity, their effectiveness is often undermined by challenges such as weak enforcement, inadequate resources, corruption, and conflicting developmental priorities. Strengthening institutional capacity, promoting community involvement, and ensuring stricter compliance are essential to enhance their effectiveness in protecting India's natural resources.

Previous Year Questions on Environment 

1. UPSC CSE - 2020

Question: "Discuss the role of India’s environmental policies in promoting sustainable development."

Answer: India’s environmental policies play a crucial role in promoting sustainable development by balancing economic growth with ecological preservation. Policies such as the National Green Tribunal (NGT) Act, Environment Protection Act, and National Biodiversity Action Plan aim to mitigate environmental degradation, regulate pollution, and conserve biodiversity. Environmental impact assessments (EIA) ensure that developmental projects comply with environmental norms. Renewable energy initiatives, afforestation programs, and water conservation projects further contribute to sustainability. These policies emphasize the need for inclusive growth, community participation, and resilience to climate change. However, effective implementation, regulatory enforcement, and addressing socio-economic disparities remain challenges in achieving sustainable development goals.

2. UPSC CSE - 2019

Question: "Evaluate the challenges faced in implementing international environmental agreements in India."

Answer: Implementing international environmental agreements in India faces several challenges, including financial constraints, inadequate infrastructure, and institutional capacity gaps. Compliance with targets set by agreements like the Paris Agreement requires significant investment in renewable energy, emission reduction, and climate adaptation measures. Socio-economic priorities, such as poverty alleviation and economic growth, sometimes conflict with environmental objectives, hindering implementation. Limited public awareness, data gaps, and bureaucratic delays further complicate efforts. Addressing these challenges demands enhanced funding, capacity building, policy coherence, and international cooperation to ensure that India meets its global environmental commitments effectively.