The Foundation topics are now the three concepts for the course, Perspectives, Systems and Sustainability. The content from Energy and Equilibria (ESS 2015) has now been integrated into Systems and Ecology. The content from Humans and Pollution (ESS 2015) has been integrated, simplified or removed. 

The new Perspectives subtopic contains a little of Environmental value systems (ESS 2015) but is largely rewritten to focus on perspectives, worldviews, values and the development of the environmental movement with a more robust requirement to look at multiple influences. We’ve expanded the detail, based on the IPBES reports and this helps support the HL lens of Ethics. 

The new Systems subtopic is fairly similar to the old but contains more details on tipping points and emergent properties. We’ve created supplemental information on complexity theory for those who are interested in these big ideas.

The new Sustainability subtopic contains a lot more detail including the concept that societal and economic sustainability are a subset and therefore reliant on environmental sustainability. This helps support the HL lens of Environmental Economics. Environmental justice is introduced in this subtopic and you will find it embedded throughout the course. A wider range of methods to measure and monitor sustainability are included such as biocapacity, carbon and water footprints, the SDGs and planetary boundaries. Doughnut economics and circular economic models are introduced and evaluated. These are also embedded throughout the course.

Topic 2, Ecology, is slightly smaller for SL and has been expanded for HL. The more practical subtopic, Investigating Ecosystems (ESS 2015) has been embedded within the other subtopics. 

In the first subtopic, Individuals and populations, communities, and ecosystems, at SL keystone species, planetary boundaries and tipping points are included in the ecology topic. At HL we will need to understand taxonomy and cladistics. Fundamental and realized niches and r and K strategies are now only at HL. 

In the second subtopic, Energy and biomass in ecosystems,  there is a more explicit and clearer set of expectations for the movement of energy and biomass through trophic levels and the consequences of this. At SL, students need to understand the broad concept of productivity while at HL the details of primary and secondary and net productivity are included. At HL maximum sustainable yields and ecological efficiency are included.

In the third subtopic, Biogeochemical cycles, agricultural techniques, carbon sequestration and ocean acidification are included in the carbon cycle with clear links to carbon sinks and the consequences of global change in the biosphere. At HL, limestone, reefs and methane are linked to the carbon cycle. The nitrogen cycle including the Haber process and the consequences for the planetary boundary are only included at HL.

The fourth subtopic, Climate and Biomes, is simplified at SL with students needing to understand the characteristics of tropical rainforests, hot deserts, tundra and two other biomes rather than the comparative approach in ESS, 2015. The tricellular model is more explicit. At HL, El Niño and La Niña are included together with the formation of tropical storms.

The fifth subtopic, Zonation, succession and change in ecosystems, at SL is largely similar to ESS, 2015, if simpler as HL now contains the more complex patterns of change through succession and the debate over what is a climax community and the concept of a plagioclimax community.

Topic 3, Biodiversity and Conservation, is the same number of hours at SL as the previous guide (ESS, 2015) but contains some important shifts in emphasis, including a focus on regenerative and community-based methods.

In the first subtopic, Biodiversity and Evolution, at SL students need to understand the role of citizen science, indigenous people and parabiologists in gathering biodiversity data. We’ve got some cool resources for this ready. At HL there’s an emphasis on a greater biological understanding of the foundations of biodiversity so students need to understand the role of mutation, sexual reproduction and reproductive isolation in the formation of biodiversity. The consequences of human activities and artificial selection on evolution are included along with biodiversity hotspots, earth history, mass extinctions, and the concept of golden spikes that mark new geological epochs such as the Anthropocene.

In the second subtopic, Human Impact on Biodiversity, at SL the only difference is the requirement to consider the tragedy of the commons. You will find that we have critiqued this approach wherever it is mentioned in the guide. At HL we have biodiversity hotspots, Key Biodiversity Areas, traditional indigenous land management, environmental justice and the assessment of the planetary boundary, “loss of biosphere integrity”.

In the final subtopic, Conservation and Regeneration, new at SL is the explicit requirement to study a UNESCO biosphere reserve, the process of rewilding and the role of perspectives and value systems in the choice of conservation strategy. At HL we have the responsiveness of organisations in conservation (was at SL in ESS, 2015), the role of positive feedback loops, an evaluation of rewilding, an evaluation of specific restoration projects and the role of ecotourism.

Topic 4, Water, there is a small reduction of hours at SL and content that was guidance is now knowledge statements. At HL there is an explicit connection between the water and carbon cycles and some topics from the old guide have been shifted to HL.

In the first subtopic, Water Systems, at SL there is an additional understanding of the role of gravity in the movement of water and the skill of calculating sustainable rates of water harvesting. At HL, there is a need to understand the chemical properties of water, the role of water bodies in carbon sequestration, acidification, stratification in water bodies and the impact of global warming and salinity changes of this. Upwellings and thermohaline circulate are at HL.

In the second subtopic, Water access, use and security, the SL content is largely similar if more clearly articulated but transboundary disputes has moved to HL. For HL, there is a requirement to consider the planetary boundary of freshwater use, the role of local and global governance, water footprints, citizen science, the difference between water stress and water security and the complexities of the provision of freshwater on an industrial scale.

In the third subtopic, Aquatic food production systems, at SL, macrophytes are included alongside phytoplankton, there is a requirement to name organisms consumed by humans, unsustainable harvesting practices are now named, students are required to be able to interpret yield/fishing effort graphs to indicate maximum sustainable yield (MSY - note how this is at HL in topic 2), the impact of climate change and ocean acidification must be considered and the role of marine protected areas and policy legislation. Controversial harvesting of species has moved to HL and has been more clearly defined. At HL students consider the factors leading to productivity in water systems, methods for determining harvest rates, application of MSY, evaluating methods for recovery of species, and the environmental justice implications of the sale of fishing rights internationally.

In the fourth subtopic, Water pollution, the content is largely similar at SL but more clearly articulated with the inclusion of plastic pollution and general water quality. Water pollutants at HL are expanded, harmful algal blooms (HABs) and the production of toxins are included at HL with the combination of factors that can amplify anoxia. Sewage treatment, indicator species for water pollution, biotic index, water quality index, drinking water guidelines and the role of regulation for this alongside citizen action.

Topic 5, Land includes the subtopics soil and agriculture and food. There is more detail at SL but this is largely making explicit what was already taught and requires more practical work. There is a reduction in the number of hours at SL.

In the first subtopic, Soil, at SL, there is more focus on the structure and assessment of soils with their role in the carbon cycle as carbon sinks. At HL there is further practical analysis of soils with the use of soil triangles now at HL and how carbon and methane can be released from soil.

In the second subtopic, Agriculture and food, at SL, there is now clearer consideration of indigenous and/or marginalised people. There are more clearly articulated definitions of farming systems, strategies for sustainable agriculture, and strategies to achieve a sustainable food supply. At HL the link between soil type and agricultural choices, regenerative agriculture, technological solutions, impacts of changing diets on sustainability, harvesting wild species, and the relationship between global food distribution patterns and malnutrition.

Topic 6, Atmosphere and climate change is reworked as it combines general structure and composition of the atmosphere with climate change and stratospheric ozone.

In the first subtopic, Introduction to the atmosphere, at SL, emphasis is placed on the science of redistribution of heat, the greenhouse effect and greenhouse gases. At HL changes at a geological scale in the climate are considered.

In the second subtopic, Climate change - causes and impact, at SL evidence for climate change is considered alongside the impacts with a clearer description of the scale of the impacts. At HL, indirect measurements for evidence are included with an evaluation of climate models, local tipping points and cascade effects and varying vulnerability as a link to climate justice.

In the third subtopic, Climate change - mitigation and adaptation, at SL there is a clearer definition of terms and processes involved in mitigation and adaptation. At HL, the range of stakeholders and actions that can be taken is included with details of the role of the UN and the IPCC, technological solutions such as smart cities, the range of perspectives and challenges faced and geoengineering.

In the final subtopic, Stratospheric ozone, at SL, the understanding is similar to the current guide (ESS, 2015) while at HL there is more detail on the role of the polar stratospheric clouds and a study of the challenges of air conditioning unit.

Topic 7, Natural resources, uses and management, has redistributed some topics from SL to HL and introduced some new nuanced understanding of resource use in the geopolitic and globalised systems that exist.

In the first subtopic, Natural resources, uses and management, at SL is similar to the current 8.2 subtopic with the addition of resource security and a consideration of factors affecting local choices in natural resource use. At HL, interventions and management strategies in resource use are to be considered with the nuances of the factors that impact the sustainability of a resource and the geopolitics of resource use and changing resource security with economic globalisation; environmental impact assessments are included at HL only.

The second subtopic, Energy resources, use and management, includes understandings from the old topic 6 (ESS, 2015) and SL now includes the challenges of intermittent energy and energy conservation. At HL, energy security (not SL), the role of finite resources, nuclear power and battery storage are included.

The third subtopic, Solid waste, all content is at SL, now includes consideration of biodegradability and the circular economy. 

Topic 8, Human populations and urban systems looks at human population demographics and the new urban systems and urban planning. Urban air pollution has moved here from the old topic 6 (ESS, 2015).

The first subtopic, Human populations, is similar to the SL unit 8.1 (ESS, 2015) with HL exploring dependency ratios, population momentum and environmental migration.

The second subtopic, Urban systems and urban planning is new for SL and starts by defining the concepts of urban systems and then urban planning. The two major understandings are about how urban planning may now consider sustainability of the system and what ecological urban planning looks like. At HL this goes into more depth on these concepts, considers how urban systems might incorporate doughnut economics or circular economy principles and how green architecture functions.

The third subtopic, Urban air pollution, at SL looks at the causes of the problem and management strategies. There is less detail than ESS, 2015. At HL. photochemical smog and tropospheric ozone are considered.

HL.a Environmental Law considers how environmental law is constructed, the idea of constitutionalism, the scope and scale of these laws, International law, courts and tribunals, and how the law works with sustainable management of resources.

HL.b Environmental Economics compares traditional economics, markets and measures of growth with environmental and ecological economics. It considers how we can place value on nature, the possibilities of de-growth and circular and doughnut economic models.

HL.c Environmental Ethics considers what ethics is and ethical frameworks, the concept of ethical value and moral standing, approaches to ethics, the appeal to nature fallacy and how environmental and social justice movements are converging on common ground.