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IB ESS Syllabus + Topics [2026 updated]

Wojtek

By Wojtek

•

04 Apr 2025

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Whether you're a current IB ESS student looking to get a deeper grasp of the syllabus or a prospective IB student weighing your Group 4 options, this post will be your guide. We'll break down the IB ESS syllabus to give you a clear understanding of what to expect in the course. 

 

 

IB ESS Syllabus + Topics

 

 

You will explore the following topics:

 

Topic 1: Foundation 

 

1.1 Perspectives 

  • This topic explores how perspectives, values, and worldviews shape environmental decision-making and actions. It examines factors like culture, economics, politics, and science that influence environmental beliefs. Students will analyze environmental value systems and how they evolve over time. HL students will also design surveys and analyze behavior-time graphs to study changing environmental attitudes. Case studies and historical influences will help students understand the role of perspectives in sustainability

 

1.2 Systems

  • Students will explore how systems consist of interacting components with inputs, outputs, storages, and flows, using systems diagrams to represent these processes. The concepts of positive and negative feedback loops, equilibrium, and tipping points will be analysed to explain how environmental systems change over time. HL students will discuss advocacy and policymaking, allowing students to explore the role of governments, NGOs, and individuals in environmental decision-making. 

 

1.3 Sustainability 

  • Students will explore sustainability as the balance of environmental, social, and economic systems for long-term viability. They will analyse resource use, biodiversity, and equity through models like the UN SDGs, ecological footprints, and circular economy principles. Case studies on ecosystem collapse and resource depletion will highlight the impacts of unsustainable practices. By using sustainability indicators, students will assess the role of individuals, businesses, and governments in promoting a sustainable future. 

 

 

Topic 2: Ecology

 

2.1 Individuals, populations, communities, and ecosystems 

  • Students will explore the biosphere, focusing on species classification, population dynamics, and ecosystem interactions. They'll study how abiotic and biotic factors influence species distribution. Students will also investigate human impacts such as deforestation and climate change, and the importance of preserving ecosystem integrity. HL students will additionally analyse evolutionary relationships using clades, explore the planetary boundaries model, and delve deeper into species life cycles and their disruption due to human activity. 

 

2.2 Energy and biomass in ecosystems 

  • Students will explore the flow of energy and matter in ecosystems, focusing on processes like photosynthesis and cellular respiration. They'll study food chains and the role of producers, consumers, and decomposers in ecosystems. HL students will additionally investigate concepts like primary and secondary productivity, sustainable yields, and ecological efficiency, with an emphasis on how energy flows and entropy increase through trophic levels.

 

2.3 Biogeochemical cycles

  • Students will examine the carbon and nitrogen cycles, and how they maintain the availability of essential elements for life. Students will explore how human activities, such as deforestation, agriculture, and the burning of fossil fuels, impact these cycles, often disrupting their balance and leading to problems like ocean acidification. HL students will further explore the role of nitrogen in fertilizers, the Haber process as well as solutions to mitigate human impacts like reforestation and sustainable agriculture.

 

2.4 Climate and biomes

  • Students will learn about climate, which refers to long-term weather patterns, and weather, which is about short-term conditions. They will explore how biomes like rainforests, deserts, and tundra are influenced by factors like temperature, rainfall, and sunlight. HL students will also look at how global warming is causing biomes to shift. They'll study the El Niño Southern Oscillation and how it affects weather and marine life. Finally, students will learn about the rise in tropical cyclones, like hurricanes and typhoons, which are becoming more intense and frequent due to warmer ocean temperatures. 

 

2.5 Zonation, succession and change in ecosystems 

  • Students will explore zonation along environmental gradients and succession, including primary and secondary stages. They will examine how energy, productivity, and biodiversity change during succession and how human activities can alter these processes. HL students will also study the role of primary consumers in shaping ecosystems and the concept of alternative stable states.

 

 

Topic 3: Biodiversity and conservation 

 

3.1 Biodiversity and evolution 

  • Students will explore biodiversity at genetic, species, and ecosystem levels and how it supports ecosystem resilience. They will examine evolution through natural selection, speciation, and the role of environmental factors in shaping biodiversity. HL students will analyze reproductive isolation, human-driven evolutionary changes, and the Anthropocene’s impact on biodiversity. 

 

3.2 Human impact and biodiversity 

  • Students will explore the human impacts on biodiversity, including habitat destruction, climate change, pollution, and invasive species. They will investigate conservation strategies, and case studies of species extinction, endangerment, and recovery. HL students will analyze biodiversity hotspots, conflicts between conservation and development, indigenous land management, environmental justice, and the planetary boundary for biosphere integrity.

 

3.3 Conservation and regeneration 

  • Students will explore the justifications for species and habitat conservation, including ecological, economic, ethical, and social perspectives. They will examine conservation strategies such as in situ and ex situ approaches, mixed conservation models, and the role of international treaties like the Convention on Biological Diversity. HL students will analyse rewilding, biodiversity restoration, conservation effectiveness, and the influence of environmental value systems. They will also assess ecotourism’s role in conservation, its benefits, and potential drawbacks. 

 

 

Topic 4: Water 

 

4.1 Water systems 

  • Students will explore the hydrological cycle, its stores and flows, and how human activities impact water distribution. They will study the physical and chemical properties of water, ocean carbon sequestration, stratification, upwellings, and thermohaline circulation. HL students will analyze how temperature, salinity, and human-induced changes affect ocean circulation and climate regulation.

 

4.2 Water access, use and security

  • This section focuses on water security, scarcity, conservation, and governance. It examines how social, economic, and political factors influence freshwater access, the impacts of industrial water use, and mitigation strategies. HL students will explore disputes and water management. Examples of conservation techniques, industrial strategies, and equity issues in water access are also included.

 

4.3 Aquatic food production systems 

  • For this section, students will cover the role of aquatic organisms in food webs, the increasing demand for seafood, and the impact of unsustainable harvesting. Topics, among the more important ones, include overfishing and aquaculture. HL students will explore fishery stock assessments, legal frameworks, and ethical issues related to marine harvesting. 

 

4.4 Water pollution 

  • Students will explore the sources and consequences of water pollution, including sewage, agricultural runoff, industrial waste, and plastic debris. They will study key environmental challenges such as eutrophication and hypoxic dead zones. HL students will examine the role of international regulations, equity issues in access to clean water, and citizen-led initiatives in combating water pollution.

 

 

Topic 5: Land

 

5.1 Soil 

  • Students will explore soil as a dynamic system with distinct inputs, outputs, storages, and flows that support life and biodiversity. They will examine soil composition, including inorganic minerals, organic matter, water, and air, and how soil horizons develop over time. Students will investigate the role of soils in the water, carbon, and nitrogen cycles, providing a foundation for plant growth and acting as a carbon sink or source. They will also analyze soil texture, nutrient content, and physical properties, which influence primary productivity and ecosystem sustainability. HL students will study the factors influencing soil formation, soil classification, and the impact of climate and geology on soil properties, highlighting the importance of sustainable soil management to prevent degradation and ensure global food security.

 

5.2 Agriculture and food

  • Students will explore land as a finite resource and examine how human population growth impacts agricultural practices. They will study the factors that influence land-use decisions, such as soil quality, climate, and socio-economic conditions, and consider marginalized groups affected by land rights issues. Students will evaluate the global challenges of food distribution, waste, and the impact of agriculture on sustainability, comparing different farming systems, such as intensive vs. sustainable agriculture. They will explore the Green Revolution’s effects and consider alternative farming techniques like regenerative farming. The role of diets in food sustainability will be examined. Finally, students will analyse food security issues. 

 

 

 

 

Topic 6: Atmosphere and climate change 

 

6.1 Introduction to the atmosphere

  • Students will explore the atmosphere as the boundary between Earth and space, focusing on how atmospheric circulation redistributes heat. They will investigate the role of greenhouse gases and aerosols in the natural greenhouse effect and human-driven global warming. Finally, students will examine how the evolution of life, particularly photosynthesis, has altered the atmospheric composition.

 

6.2 Climate change – causes and impacts

  • Students will explore the factors influencing climate, such as temperature, precipitation, and anthropogenic emissions. They will analyze how human activities have enhanced the greenhouse effect, causing global warming and climate change impacts on ecosystems and societies. The role of feedback loops, tipping points, and climate models in understanding future scenarios will be examined, alongside the varying responsibilities and vulnerabilities of countries to climate change. Students will consider the equity implications of climate justice and analyze long-term data to study climate trends. 

 

6.3 Climate change mitigation and adaptation 

  • Students will explore international cooperation on climate change and examine mitigation and adaptation strategies. They will analyze the roles of governments, NGOs, and individuals in addressing climate change, and consider challenges such as financial barriers and differing perspectives. HL students will focus on the emerging technologies, geoengineering, and the tragedy of the commons.

 

6.4 Stratospheric zone

  • Students will explore the Sun’s electromagnetic radiation and its impact on the biosphere, with a focus on UV radiation and its harmful effects. They will study the role of stratospheric ozone in protecting life by absorbing UV radiation, and the consequences of ozone depletion, including the impacts on ecosystems and human health. HL students will analyze chemical reactions related to ozone formation and destruction, the success of the Montreal Protocol, and the use of HFCs and alternatives.

 

 

Topic 7: Natural resources

 

7.1 Natural resources – uses and management 

  • Students will explore natural resources and their role in society, focusing on natural capital, natural income, and ecosystem services. They will investigate renewable and non-renewable resources, the importance of managing natural capital sustainably, and how resource security impacts societies. HL students will analyze factors affecting resource use, including political, economic, and cultural factors, and evaluate management strategies such as EIAs and government interventions. They will also explore the challenges of resource insecurity, the effects of economic globalization, and how changes in demand, supply, and technology can improve resource security.

 

7.2 Energy sources – uses and management 

  • Students will explore renewable and non-renewable energy sources, their sustainability, and environmental impacts. They’ll investigate factors influencing energy choices, such as cost, pollution, and security, and examine energy storage solutions. Students will analyze the global dependence on fossil fuels, nuclear power, and the environmental costs of mining for resources like lithium and cobalt. HL students will focus on the depletion of fossil fuels and the geopolitical effects of energy resource distribution.

 

7.3 Solid waste

  • Students will explore waste generation from domestic, industrial, and agricultural sources, focusing on types like e-waste, food waste, and biohazardous materials. They will investigate how waste composition varies due to socio-economic, political, environmental, and technological factors. The environmental and social impacts of waste, including pollution and the issue of transporting waste internationally, will also be studied. Students will examine sustainable waste management strategies.

 

 

Topic 8: Human populations and urban systems 

 

8.1 Human populations

  • Students will study human population dynamics, including birth rates, death rates, immigration, and emigration. They will learn about key measures like total fertility rate, life expectancy, and doubling time. Students will explore population models, the demographic transition model, and age-sex pyramids. HL students will study the impact of policies and socio-economic factors on population growth. They will also examine environmental migration due to climate change and analyze demographic trends using secondary data.

 

8.2 Urban systems and urban planning 

  • Students will study urban ecosystems, urban areas, and their systems, including infrastructure, transport, and waste management. They will explore urbanization, rural-urban migration, suburbanization, and environmental impacts. Students will learn about urban planning, sustainability, and green architecture, including models like circular economy and doughnut economics. HL students will focus on urban systems as ecosystems and the benefits of urban compactness and mixed land use.

 

8.3 Urban air pollution 

  • Students will study urban air pollution, its sources, and primary pollutants like NOx, sulfur dioxide, carbon monoxide, and particulate matter. They will explore the chemistry of acid rain, its ecological and human impacts, and management strategies for reducing air pollution, such as improved transportation, green spaces, and catalytic converters. HL students will focus on photochemical smog, meteorological factors affecting its formation, and the biological and physical impacts of tropospheric ozone. They will also analyze the societal and economic consequences of air pollution.

 

 

 

HL Lenses

 

Apart from the additional content outlined, HL students study the IB ESS syllabus through the prism of three lenses:

  • Environmental law
  • Environmental economics
  • Environmental ethics

 

Environmental law

  • Students explore the syllabus through the lense of environmental laws, focusing on promoting ecological sustainability and social justice. Students will examine environmental constitutionalism, international law, and agreements like the Paris Agreement, CITES, and IUCN, and their effectiveness in addressing various issues. They will look at the application of international environmental law in courts and tribunals, and how legal personhood for natural entities enhances environmental protection. 

 

Environmental economics

  • Students study the syllabus through the lense of environmental economics, exploring how economics can address environmental issues and ensure sustainability. Students will examine market failures and solutions. Students will explore the tragedy of the commons and environmental accounting. They will investigate the economic valuation of ecosystem services, the impact of economic growth on the environment, and the concept of eco-economic decoupling. Students will also study models like circular economy and doughnut economics, which aim to promote sustainability and address inequality.

 

Environmental ethics

  • Students study the syllabus through the lense of environmental ethics, examining different moral perspectives on humanity’s responsibility toward nature. They will study moral standing and ethical frameworks such as virtue ethics, consequentialism, and rights-based ethics. The course will also cover concepts like the land ethic, ecocentrism, and anthropocentrism, analyzing how these viewpoints influence sustainability efforts. Additionally, students will explore the intersection of environmental and social justice movements, discussing the ethical implications of human dominance over nature and its parallels to issues like sexism, racism, and intergenerational equity.

 

 

 

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