Environmental Science: Earth Systems & Climate

Name: Environmental Science: Earth Systems & Climate
Rating: 4.6 (41 reviews)

Master the science behind climate, ecology, pollution, and energy so you can evaluate environmental claims with rigor

Bestseller

Role Play

Created byISO Horizon

Last updated 6/2026

English

What you'll learn

Explain Earth's energy balance, the greenhouse effect, and why trace gases drive climate
Trace the carbon cycle's fast and slow loops and quantify human disruption in gigatonnes
Interpret climate models, scenarios, and feedback loops including ice-albedo and water vapor
Analyze population dynamics, food webs, biodiversity metrics, and ecosystem services
Diagnose air pollution chemistry, eutrophication, acid deposition, and emerging contaminants
Compare fossil, nuclear, and renewable energy on carbon intensity, land use, and life-cycle costs
Apply maximum sustainable yield reasoning to fisheries, forests, water, and soils
Evaluate environmental claims using the planetary boundaries framework
Distinguish natural climate variability from anthropogenic signals using multiple evidence lines
Read scientific summaries critically by checking units, timescales, and system boundaries

Course content

21 sections • 126 lectures • 6h 1m total length

The Four Spheres of Earth8:34
Introduce yourself to the atmosphere, hydrosphere, lithosphere, and biosphere as the four interacting domains that together define environmental science. Explain how each sphere is defined by its dominant state of matter and chemistry, then walk through concrete exchanges at the boundaries — rainfall transferring water from atmosphere to hydrosphere, weathering linking lithosphere to soils, photosynthesis coupling biosphere to atmosphere. Emphasize that environmental problems almost always involve disruptions that propagate across multiple spheres, which is why a systems perspective is non-negotiable. Use vivid concrete examples like a single raindrop's journey or a carbon atom moving between a leaf, the soil, and the ocean. Keep the tone curious and grounded in observable phenomena rather than abstract theory.
Atmosphere: Composition and Structure8:39
Walk the learner through the layered structure of Earth's atmosphere, from troposphere to exosphere, explaining what changes with altitude in terms of temperature, pressure, and density. Detail the major gases — nitrogen at 78 percent, oxygen at 21 percent, argon, and the trace gases including carbon dioxide, methane, water vapor, and ozone — and explain why trace gases matter disproportionately for climate and life. Connect each layer to a phenomenon the student already knows: weather happens in the troposphere, commercial jets fly in the stratosphere, the ozone layer protects from ultraviolet radiation, and auroras occur in the thermosphere. Make clear why understanding atmospheric structure is the prerequisite for understanding pollution behavior, climate dynamics, and weather.
Earth's Energy Balance and the Greenhouse Effect9:32
Explain how Earth maintains a roughly stable temperature by balancing incoming solar shortwave radiation against outgoing terrestrial longwave radiation. Walk through the planetary albedo concept, the role of clouds, ice, and surface cover, and how greenhouse gases selectively absorb outgoing infrared while remaining transparent to visible light. Distinguish the natural greenhouse effect, which makes Earth habitable by raising surface temperature roughly 33 degrees Celsius, from the enhanced greenhouse effect driven by additional carbon dioxide, methane, and nitrous oxide. Use the analogy of a car parked in sunlight, but immediately refine it so the learner understands the actual radiative physics rather than the popular oversimplification.
Hydrosphere: The Water Cycle and Ocean Circulation9:59
Trace water through evaporation, transpiration, condensation, precipitation, infiltration, runoff, and groundwater storage, emphasizing residence times that range from days in the atmosphere to thousands of years in deep aquifers. Then introduce ocean circulation as two coupled systems — wind-driven surface currents like the Gulf Stream and density-driven thermohaline circulation often called the global conveyor belt. Explain how salinity and temperature gradients power deep water formation in the North Atlantic and around Antarctica, and why this circulation moves heat around the planet on millennial timescales. Tie this to climate by noting how disruptions to thermohaline circulation could reorganize regional climates dramatically.
Lithosphere: Rock Cycle, Soil, and Plate Tectonics10:49
Introduce the rock cycle as the slow transformation between igneous, sedimentary, and metamorphic rocks driven by heat, pressure, weathering, and erosion. Explain plate tectonics as the engine behind mountain building, earthquakes, volcanism, and the long-term carbon cycle through subduction and outgassing. Then zoom into soil formation, describing how parent rock, climate, organisms, topography, and time produce distinct soil horizons. Make the case that soil is a thin, slow-forming, irreplaceable resource on human timescales, and connect this to agriculture, erosion, and land degradation issues that will reappear later in environmental discussions.
Biosphere and Biogeochemical Cycles7:42
Frame the biosphere as the thin film of life that mediates flows of carbon, nitrogen, phosphorus, sulfur, and water across the other spheres. Detail each major biogeochemical cycle with its reservoirs, fluxes, and timescales — carbon's exchange between atmosphere, oceans, vegetation, and sediments; nitrogen's fixation, nitrification, and denitrification pathways; phosphorus moving from rock to soil to organisms with no significant atmospheric phase. Explain why human disruption of these cycles, especially nitrogen and carbon, is one of the most significant environmental signals of the modern era. Ground the cycles in tangible examples like a soybean root nodule or a coral reef built atop dissolved carbonate.
Section 1 Quiz: Earth Systems Science Foundations
Roleplay: Earth Systems Science Foundations

The Carbon Cycle in Detail7:13
Walk through the carbon cycle as a system of fast and slow loops. The fast loop moves carbon between atmosphere, ocean surface, vegetation, and soils on timescales of years to centuries through photosynthesis, respiration, and air-sea gas exchange. The slow loop locks carbon into sedimentary rocks, fossil fuels, and the deep ocean over millions of years through weathering, burial, and subduction. Quantify the major reservoirs in gigatonnes of carbon and the annual fluxes between them, then show where anthropogenic emissions of roughly 10 gigatonnes per year fit into this picture. Make clear that the issue is not the existence of carbon dioxide but the rate at which slow-loop carbon is being transferred into the fast loop.
Natural Climate Variability Across Timescales7:30
Explore how Earth's climate has varied naturally across multiple timescales long before human influence. Cover Milankovitch cycles — eccentricity, obliquity, and precession — driving ice age rhythms over tens of thousands of years. Discuss solar variability, volcanic forcing, and internal modes like the El Niño Southern Oscillation, the Pacific Decadal Oscillation, and the North Atlantic Oscillation. Emphasize that recognizing natural variability is essential to detecting and attributing the human signal, not a reason to dismiss anthropogenic change. Use clear examples like the Little Ice Age, the Medieval Climate Anomaly, and the Pinatubo eruption's brief global cooling effect.
Evidence for Anthropogenic Climate Change9:19
Lay out the converging lines of evidence that current climate change is driven primarily by human activity. Cover instrumental temperature records, ice core data showing carbon dioxide concentrations correlated with temperature over 800,000 years, isotopic fingerprinting that distinguishes fossil carbon from biological carbon, ocean heat content rising consistently, satellite measurements of outgoing longwave radiation in greenhouse gas wavelengths, and observed stratospheric cooling that matches greenhouse forcing rather than solar forcing. Frame this as the scientific method working — multiple independent measurements pointing to the same conclusion — and explain why each line of evidence rules out specific alternative hypotheses.
Climate Models and Projections9:56
Explain what a general circulation model actually is — a three-dimensional grid of the atmosphere, ocean, land, and ice with physical equations solved at each grid cell over time steps. Discuss how models are validated by hindcasting historical climate, how ensemble runs quantify uncertainty, and how Shared Socioeconomic Pathways generate scenarios from low to high emissions. Distinguish between projections and predictions, and clarify why uncertainty grows with longer time horizons and finer spatial scales. Use concrete examples like the spread of projected sea level rise by 2100 across different scenarios to make the abstract idea of model uncertainty tangible.
Climate Feedback Loops10:46
Introduce feedback as a process in which a change in one variable amplifies or dampens itself through the system. Detail the major positive feedbacks: ice-albedo feedback, where melting ice exposes darker surfaces that absorb more heat; water vapor feedback, where warmer air holds more water vapor amplifying greenhouse warming; and carbon cycle feedbacks like permafrost methane release and reduced ocean carbon uptake. Cover negative feedbacks such as enhanced longwave emission with temperature and certain cloud responses. Emphasize that feedbacks determine climate sensitivity, the central uncertain parameter that decides whether a given emissions pathway produces moderate or severe warming.
Observed and Projected Climate Impacts7:42
Survey the impacts of climate change already observed and those projected under various warming scenarios. Cover sea level rise driven by thermal expansion and ice sheet loss, with current rates around 4 millimeters per year and projections by 2100. Discuss shifts in precipitation patterns, intensification of extreme weather including heat waves and heavy rainfall events, ocean acidification from carbon dioxide uptake lowering ocean pH, ecosystem disruptions like coral bleaching and species range shifts, and agricultural and water security implications. Keep the framing scientific — these are physical and ecological consequences of measurable changes, presented without political editorializing.
Section 2 Quiz: Climate Science and Change
Roleplay: Climate Science and Change

Population Dynamics and Carrying Capacity11:12
Explain how populations grow and stabilize under different conditions. Distinguish exponential growth, characteristic of populations with abundant resources, from logistic growth, which incorporates a carrying capacity limit set by resources and density-dependent factors. Introduce r-selected and K-selected life history strategies with examples like bacteria versus elephants. Cover density-dependent factors such as disease and competition, alongside density-independent factors like storms and fires. Make the math intuitive by showing how doubling times compress dramatically under exponential growth, and connect this directly to human population dynamics and resource demand.
Community Interactions9:33
Walk through the ways species interact within ecological communities. Define competition as a negative-negative interaction and introduce the competitive exclusion principle along with resource partitioning that allows coexistence. Cover predation including parasitism and herbivory, mutualism with examples like pollinators and flowering plants or mycorrhizal fungi and tree roots, and commensalism. Use vivid concrete examples — barnacles on whales, cleaner fish at reef stations, the gut microbiome — to make these categories memorable. Emphasize that real communities are webs of overlapping interactions, not tidy one-to-one relationships.
Energy Flow and Food Webs8:44
Show how energy moves through ecosystems starting from primary producers capturing solar energy through photosynthesis, then up trophic levels via herbivory and predation, losing roughly 90 percent at each transfer to heat through respiration. Explain why this ten percent rule limits food chain length and concentrates pollutants like mercury through biomagnification. Distinguish food chains as linear simplifications from food webs as the actual interconnected reality. Use a familiar ecosystem like a temperate forest or coral reef to anchor these concepts, and connect energy flow to the productivity differences between biomes.
Ecosystem Services7:43
Introduce the framework that categorizes the benefits ecosystems provide to humans into provisioning services like food, water, and timber; regulating services like climate regulation, water purification, and pollination; supporting services like soil formation and nutrient cycling; and cultural services like recreation and aesthetic value. Discuss attempts to value these services economically, the limitations of monetary valuation, and why ecosystem services often go unaccounted for in markets. Ground the abstract concept with specific examples — wetlands filtering wastewater, bees pollinating crops worth hundreds of billions annually, mangroves buffering coastal storm surges.
Ecological Succession11:45
Explain ecological succession as the predictable sequence of community changes following a disturbance or on newly exposed surfaces. Distinguish primary succession on bare rock or new volcanic land, where soil must develop first through pioneer species like lichens, from secondary succession on previously vegetated land where seed banks and soil persist. Walk through stages from pioneers to intermediate communities to a relatively stable climax community, while acknowledging modern ecology's emphasis on disturbance and patch dynamics rather than fixed endpoints. Use examples like a glacier retreat sequence or an abandoned agricultural field reverting to forest.
Biodiversity: Measurement and Loss8:51
Define biodiversity across three nested scales — genetic diversity within species, species diversity within communities, and ecosystem diversity across landscapes. Introduce metrics like species richness, Shannon and Simpson diversity indices, and beta diversity between sites. Cover the major drivers of biodiversity loss summarized in the HIPPO acronym — habitat destruction, invasive species, pollution, population growth, and overharvesting — and discuss current extinction rates estimated at hundreds to thousands of times the background rate. Frame extinction as both an ethical and a practical concern given biodiversity's role in ecosystem resilience and services.
Section 3 Quiz: Ecology and Biodiversity
Roleplay: Ecology and Biodiversity

Air Pollution and Criteria Pollutants8:31
Cover the six criteria pollutants regulated under modern air quality standards — particulate matter, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen oxides, and lead — explaining their sources, chemistry, and health effects. Distinguish primary pollutants emitted directly from secondary pollutants formed in the atmosphere through reactions. Walk through photochemical smog formation in urban areas where nitrogen oxides and volatile organic compounds react in sunlight to produce ozone. Address particulate matter size classes PM10 and PM2.5 and why smaller particles penetrate deeper into the lungs. Keep the framing scientific by linking emissions chemistry to observed concentrations and health outcomes.
Acid Deposition and Atmospheric Chemistry9:00
Explain how sulfur dioxide and nitrogen oxides emitted from combustion react with water and oxygen in the atmosphere to form sulfuric and nitric acids, returning to surfaces as wet or dry acid deposition. Detail the ecological consequences — acidification of lakes and streams below pH thresholds where fish reproduction fails, leaching of aluminum and calcium from soils, and damage to forest canopies, especially at high elevations. Cover the policy response history briefly to ground the science in real outcomes, showing how acid rain became a textbook example of an environmental problem identified, quantified, and substantially mitigated through emission controls.
Water Pollution: Sources and Eutrophication11:04
Distinguish point sources of water pollution like a factory discharge pipe from nonpoint sources like agricultural runoff spread across a watershed. Cover major pollutant categories including pathogens, oxygen-demanding wastes, plant nutrients, toxic chemicals, sediment, and thermal pollution. Walk through eutrophication in detail — how excess nitrogen and phosphorus fuel algal blooms, which die, decompose, and consume dissolved oxygen, creating hypoxic dead zones like the one in the Gulf of Mexico. Connect water quality measurements like biological oxygen demand, dissolved oxygen, and nutrient concentrations to observable ecosystem outcomes.
Emerging Contaminants and Soil Pollution7:37
Introduce a class of pollutants that traditional treatment systems were not designed to remove — pharmaceuticals, personal care products, microplastics, per- and polyfluoroalkyl substances often called forever chemicals, and endocrine disruptors. Discuss their persistence, bioaccumulation potential, and the challenges of detection at parts per trillion. Then turn to soil contamination from heavy metals like lead and cadmium, persistent organic pollutants, and petroleum residues, covering how contaminants bind to soil particles, leach into groundwater, and enter food chains. Explain remediation strategies including bioremediation and phytoremediation at a conceptual level.
Waste Management Hierarchy10:14
Present the waste management hierarchy as a ranking from most preferred to least preferred — source reduction, reuse, recycling, energy recovery, treatment, and disposal. Quantify global waste generation and composition, distinguishing municipal solid waste, industrial waste, and hazardous waste streams. Cover the realities of recycling markets, contamination rates in single-stream recycling, and why some materials are economically recyclable while others are not. Discuss modern sanitary landfills with liner systems and methane capture, waste-to-energy incineration with emission controls, and composting for organic fractions. Keep the analysis grounded in mass balances rather than slogans.
Section 4 Quiz: Pollution and Waste Systems
Roleplay: Pollution and Waste Systems

Fossil Fuels: Formation, Extraction, and Impacts9:52
Trace coal, oil, and natural gas back to their geological origins as ancient organic matter buried, heated, and pressurized over millions of years. Explain extraction methods from conventional drilling to hydraulic fracturing and mountaintop removal, and detail the environmental footprints of each — habitat disruption, water consumption and contamination, methane leakage, and combustion emissions. Quantify the energy densities and carbon intensities that explain why fossil fuels dominated the twentieth century. Frame the conversation around honest accounting of both benefits and external costs rather than caricature.
Nuclear Energy: Fission, Waste, and Risk11:12
Explain nuclear fission as the splitting of heavy isotopes like uranium-235 to release energy, walk through how reactors sustain controlled chain reactions, and cover the main reactor designs in commercial use. Address the full fuel cycle from mining and enrichment to spent fuel and long-term waste management, including the distinction between low-level and high-level radioactive waste. Discuss reactor accidents at Chernobyl, Three Mile Island, and Fukushima in terms of what physically happened and what was learned. Cover the actuarial reality of nuclear's death rate per unit energy compared with other sources, and the unresolved policy question of geological waste storage.
Solar and Wind Energy12:08
Cover photovoltaic solar cells converting photons to electricity through the semiconductor band gap, and concentrated solar power using mirrors to drive thermal turbines. Then walk through wind turbines extracting kinetic energy from moving air, with the Betz limit capping theoretical efficiency at 59 percent. Discuss capacity factors, intermittency, and the resulting need for storage or grid balancing. Address the often-overlooked environmental trade-offs — land use, raw material requirements for panels and turbines, end-of-life disposal, and impacts on birds, bats, and local ecosystems. The goal is a clear-eyed view of what these technologies do well and where their costs lie.
Hydroelectric, Geothermal, and Biomass10:59
Explore three additional renewable energy sources with distinct geographies and trade-offs. Hydroelectric power converts gravitational potential energy of water into electricity through dam turbines, providing dispatchable low-carbon power but disrupting river ecosystems, sediment transport, and fish migration. Geothermal taps Earth's internal heat through wells, viable where the crust is hot and water can circulate, with minor seismic and groundwater concerns. Biomass energy from wood, crop residues, or dedicated energy crops cycles atmospheric carbon if managed sustainably but raises land-use and air quality questions. Compare honest energy returns on energy invested for each.
Comparing Energy Sources on Real Metrics8:47
Bring all energy sources into a common framework using life-cycle assessment metrics. Compare grams of carbon dioxide equivalent per kilowatt hour, land use per terawatt hour, water consumption, material intensity, deaths per unit energy from accidents and pollution, and capacity factors. Show how each source ranks differently on each metric, undermining any simple narrative that one technology is universally best or worst. Equip the student to read claims about energy critically by checking which metric is being cited and whether life-cycle boundaries are honestly drawn. This is rigorous comparative analysis, not advocacy.
Section 5 Quiz: Energy Systems and Trade-offs
Roleplay: Energy Systems and Trade-offs

Freshwater Resources and Management6:57
Frame freshwater as a small fraction of Earth's water — about 2.5 percent total, with most locked in ice or deep groundwater — leaving rivers, lakes, and accessible aquifers as the working supply. Distinguish blue water in surface and groundwater systems from green water in soil moisture, and from gray water associated with pollution dilution. Walk through aquifer depletion examples like the Ogallala and Central Valley, surface water allocation conflicts like the Colorado River, and desalination as an energy-intensive but expanding option. Connect water stress indices to agricultural, industrial, and municipal demand patterns.
Deforestation and Land Use Change8:28
Quantify global forest cover and its change over recent decades, distinguishing tropical, temperate, and boreal biomes with their different deforestation drivers — cattle ranching and soy in the Amazon, palm oil in Southeast Asia, fuelwood and agriculture in parts of Africa. Connect land use change to carbon emissions, biodiversity loss, altered hydrological cycles, and soil degradation. Cover reforestation and afforestation distinctions, and the limitations of tree planting as a climate solution given timescales and ecosystem complexity. Use satellite-derived data references conceptually to ground claims in observable, measured change.
Fisheries and Marine Resource Management10:37
Explain maximum sustainable yield as the theoretical harvest rate that maintains a fish population at the size producing maximum growth, and why real-world fisheries frequently overshoot it due to estimation uncertainty and economic pressure. Cover the cascade of consequences from overfishing — collapsed cod fisheries off Newfoundland, bycatch of non-target species, bottom trawling damage to benthic habitats, and trophic cascades when top predators are removed. Discuss aquaculture's growth as both a relief and a new pressure depending on feed inputs and habitat conversion. Frame fisheries management as a textbook commons problem requiring science-based quotas.
Minerals, Metals, and Material Flows10:05
Walk through the extraction and refining of metals critical to modern technology — copper for wiring, iron for steel, aluminum for lightweight structures, lithium and cobalt for batteries, and rare earth elements for magnets and electronics. Cover environmental impacts including overburden removal, acid mine drainage, tailings storage, and energy-intensive smelting. Introduce ore grades declining over time and the consequent increase in energy and waste per unit metal. Discuss recycling rates by metal, the concept of urban mining from discarded electronics, and why some materials are economically and technically more recyclable than others.
Planetary Boundaries Framework7:31
Introduce the planetary boundaries framework that identifies nine Earth-system processes where human activity risks pushing the planet out of the stable Holocene state — climate change, biosphere integrity, biogeochemical flows of nitrogen and phosphorus, ocean acidification, land system change, freshwater use, stratospheric ozone depletion, atmospheric aerosol loading, and novel entities like synthetic chemicals. Explain which boundaries are estimated to be transgressed and which remain within safe limits. Discuss the framework's strengths in providing a quantified science-based dashboard and its limitations in defining precise thresholds. Frame it as a synthesis tool that ties together everything covered across Earth systems.
Sustainable Yield and Resource Stewardship9:39
Tie the section together by examining sustainable yield as a unifying principle across renewable resources — fisheries, forests, aquifers, soils — defined as harvest rates that do not deplete the underlying stock. Contrast renewable resources with stock-limited nonrenewables like fossil fuels and high-grade ores, where the question shifts from yield to substitution and efficiency. Walk through the concept of natural capital and how depleting it differs from drawing income from it. Close with the scientific literacy needed to evaluate claims about sustainability — checking units, timescales, system boundaries, and trade-offs rather than accepting labels at face value.
Section 6 Quiz: Resource Management and Planetary Boundaries
Roleplay: Resource Management and Planetary Boundaries

Requirements

High school level chemistry including basic atoms, molecules, and reactions
High school level biology covering cells, photosynthesis, and ecosystems
Comfort with units, percentages, and reading simple graphs and charts
Curiosity about how Earth systems work without prior environmental coursework required

Description

This course contains the use of artificial intelligence.

Environmental headlines come at you faster than ever — climate tipping points, microplastics in your blood, biodiversity collapse, the next miracle energy technology. Behind every headline sits actual science: physics, chemistry, biology, and Earth systems that you can learn to read for yourself. This course gives you the scientific literacy to evaluate environmental claims on their merits rather than relying on talking points, so you can form your own informed view of one of the defining issues of your lifetime.

You will build a coherent understanding of Earth as a system of interacting spheres, then dive deep into the physics of the atmosphere and the greenhouse effect, the carbon cycle in fast and slow loops, climate models and feedback mechanisms, and the converging lines of evidence for anthropogenic climate change. You will learn ecology from population dynamics and community interactions through ecosystem services, succession, and biodiversity metrics. You will study pollution chemistry across air, water, and soil, including criteria pollutants, eutrophication, acid deposition, and emerging contaminants like microplastics and forever chemicals. The course breaks down energy systems honestly — fossil fuels, nuclear fission, solar, wind, hydroelectric, geothermal, and biomass — comparing them on life-cycle metrics like carbon intensity, land use, material requirements, and deaths per terawatt hour. You will finish with resource management of freshwater, forests, fisheries, and minerals, all integrated through the planetary boundaries framework.

This course is designed for university students entering introductory environmental science, professionals transitioning into sustainability or ESG roles, and curious learners who want science rather than slogans. No prior environmental science background is required, only basic high school chemistry and biology. By the end you will be able to read scientific summaries critically, understand the assumptions behind climate projections, weigh real energy trade-offs, and recognize when a claim is supported by data versus when it is hand-waving.

What sets this course apart is rigorous neutrality — no activism, no doom, no dismissal, just the science as currently understood with uncertainties named honestly. Enroll now and build the scientific foundation that lets you think clearly about the environmental questions shaping the century ahead.

Who this course is for:

University students taking introductory environmental science courses
Professionals transitioning into sustainability, ESG, or climate-related roles
Engineers and analysts who need scientific grounding for energy or policy work
Journalists, writers, and communicators covering environmental topics
Lifelong learners seeking rigorous science literacy on climate and ecology

Environmental Science: Earth Systems & Climate

What you'll learn

Explore related topics

Course content

Section 1: Earth Systems Science Foundations7 lectures • 55min

Section 2: Climate Science and Change7 lectures • 52min

Section 3: Ecology and Biodiversity7 lectures • 58min

Section 4: Pollution and Waste Systems6 lectures • 46min

Section 5: Energy Systems and Trade-offs6 lectures • 53min

Section 6: Resource Management and Planetary Boundaries7 lectures • 53min

Foundations of Environmental Science0

Population Dynamics and Human Impact0

Biodiversity and Conservation Biology0

Environmental Chemistry and Pollution0

Requirements

Description

Who this course is for: