Resources & Human Decisions — Print · Earth & Space Science, Grade 9

Natural Resources: Renewable & Nonrenewable

Learning goals

• I can classify natural resources as renewable or nonrenewable.
• I can explain why fossil fuels are considered nonrenewable.
• I can explain why Earth's resources are unevenly distributed around the world.

Readings for this unit

• A design decision that people can inspect and revise

A natural resource is anything from the Earth that people put to use — the water you drink, the soil that grows your food, the minerals in your phone, the timber in your house, and the energy in sunlight or coal. Scientists sort these resources into two big groups, and the dividing line is a single question: how fast can nature make more? The answer splits everything into renewable and nonrenewable.

Renewable resources are replenished on a timescale that actually matters to human lives. The Sun keeps shining, the wind keeps blowing, rivers keep flowing (which is why we can spin turbines with them for hydropower), and a forest can regrow within a few decades if it's cut carefully. These resources aren't gone the moment you use them — nature refills the tank fast enough to keep up, as long as we don't take too much too quickly.

Nonrenewable resources, by contrast, take millions of years to form — far, far longer than any human lifetime — so once we use them up, they're effectively gone for good. Fossil fuels are the headline example. Coal formed from the buried remains of ancient swamp forests; oil and natural gas formed from tiny marine organisms that drifted down and settled on the sea floor. In both cases, layer upon layer of sediment buried those remains, and over millions of years the enormous heat and pressure underground slowly cooked them into the fuels we drill and mine today. Technically the Earth is *still* making more — but at a pace of millions of years, nowhere near fast enough to replace what we burn in a single afternoon of driving and heating. Mined metals and minerals are nonrenewable for the same reason.

Here's something that has shaped world history: these resources aren't spread evenly around the planet, and that's no accident — it's a direct fingerprint of geology. Coal turns up where ancient swampy forests once grew; oil and gas collect where old seafloor sediments were buried and heated just right; valuable metal ores concentrate where specific volcanic or hot-water (hydrothermal) processes packed them into the rock. So whether a country sits atop vast oil reserves or almost none comes down to what was happening at that exact spot on Earth millions of years ago — long before any borders were drawn.

One last catch, and it's an important one: 'renewable' does not automatically mean unlimited or harmless. A forest is renewable, but chop it down faster than it can regrow and you'll still lose it. Groundwater in an underground aquifer is renewable, but pump it out faster than rain and snowmelt can refill it and it will still run dry. In other words, whether a resource lasts depends not only on how nature classifies it, but on how wisely we choose to use it — which is exactly the challenge the next lesson takes up.

Renewable describes replenishment on a relevant human timescale, not an unlimited supply. Groundwater or forests can be depleted when withdrawal exceeds replacement. Nonrenewable resources form too slowly to replace typical human use on that timescale.

Energy-resource comparisons should include production, reliability, land use, emissions and wastes. Operational emissions and life-cycle emissions answer different questions. A low value in one category does not establish a universally best choice.

State the service being supplied, such as electricity for one community over a year. Compare options using the same demand and boundaries, and identify storage or grid needs when supply varies. Use supplied or dated values rather than presenting an old example as today's statistics.

Worked examples

Avoid these mistakes

• Renewable resources can still be overused.

Words to know

natural resource

Any material that comes from Earth and that people use, such as water, minerals, soil, or energy sources.

renewable resource

A natural resource that is naturally replenished on a human timescale, such as sunlight, wind, flowing water, and timber if harvested responsibly.

nonrenewable resource

A natural resource that takes millions of years to form and is used up far faster than nature can replace it, such as fossil fuels and mined metals.

fossil fuel

A nonrenewable energy resource — coal, oil, or natural gas — formed from the buried remains of ancient organisms transformed by heat and pressure over millions of years.

How long will it last? The tricky math of 'reserves'

News reports sometimes state we have '50 years' of oil left, calculated as proven reserves divided by current annual consumption — but that number is far less fixed than it sounds. It changes constantly as companies discover new deposits, as new technology (like fracking, which unlocked oil and gas previously considered unreachable) makes previously unusable reserves extractable, and as consumption itself rises or falls. A 'reserves-to-production' estimate is really a snapshot of today's economics and technology, not a hard deadline — which is exactly why headlines about running out of oil 'by such-and-such year' have been made, and proven wrong, for over a century.

The underground plumbing that traps oil and gas

Oil and natural gas don't just pool in giant underground caverns — they form in a fine-grained source rock, then slowly migrate through cracks and pores into a nearby reservoir rock, typically a more porous, permeable rock like sandstone that can soak them up like a sponge. For that oil or gas to actually accumulate somewhere worth drilling, it needs to be sealed in place by a cap rock — an impermeable layer like shale that traps it underneath, often within a curved, dome-shaped rock structure called an anticline. Understanding this underground plumbing system is exactly what petroleum geologists use to decide where drilling is likely to succeed.

The new resource race: critical minerals and rare earths

Fossil fuels aren't the only unevenly distributed nonrenewable resources causing global concern today. Batteries, solar panels, wind turbines, and smartphones all depend on critical minerals like lithium, cobalt, and rare earth elements, which — just like oil and coal — are concentrated in specific locations because of the particular geologic processes that formed them. A large share of the world's rare earth element processing today happens in China, giving that geologic distribution real economic and political weight, and pushing countries (including the United States) to search for new domestic sources of these modern, technology-critical resources.

New York's own fossil fuel history — and a modern controversy

The modern oil industry itself was essentially born just over the Pennsylvania-New York border, when Edwin Drake drilled the first commercially successful oil well near Titusville, PA, in 1859. More recently, the Marcellus Shale, a natural-gas-rich rock layer underlying much of upstate New York and Pennsylvania, became the center of a major modern resource debate: extracting its gas requires hydraulic fracturing ('fracking'), a technique New York State ultimately banned in 2014 over concerns about groundwater contamination and earthquakes — even as neighboring Pennsylvania embraced it, making this resource question a real, ongoing regional policy debate.

Ancient seas left salt beneath central New York

Hundreds of millions of years ago, a shallow sea repeatedly covered what is now central and western New York and evaporated under a hot, arid climate, leaving behind thick layers of rock salt. Today, mines near the town of Retsof, NY, tap into one of the largest salt deposits in the world, an economically valuable nonrenewable resource formed entirely by ancient evaporation, in the same rock-forming family as the evaporite sedimentary rocks described elsewhere in this course — proof that resources described in this unit and rock-forming processes described earlier are really the same story.

In the real world

Deciding whether to heat a Westchester home with natural gas or with solar panels and a heat pump comes down to weighing a nonrenewable resource against renewable ones.

Exit check

Why can a renewable resource still be depleted locally?

Human Impact & Stewardship

Learning goals

• I can explain how population growth and per-capita consumption combine to increase total demand on Earth's resources.
• I can describe stewardship strategies that reduce human impact on Earth's systems.
• I can explain why sustainability means meeting today's needs without compromising future generations.

Readings for this unit

• A design decision that people can inspect and revise

How much strain humanity puts on the Earth comes down to two numbers multiplied together: how many people there are (population) and how much each person uses on average (per-capita consumption). Multiplication is the key word. If either number rises, total demand rises — but when population grows *and* each person also consumes more, the two effects stack up and demand can balloon far faster than either one alone. Ten times as many people, each using twice as much, isn't ten or twelve times the demand — it's twenty times. That multiplying is why rising living standards across a growing global population put such enormous pressure on resources.

That swelling demand ripples through every one of Earth's systems. Resources get drawn down faster than before. More waste and pollution pour into the air, water, and soil. Forests and wetlands are cleared to make room for farms, mines, roads, and cities, shrinking the habitats that wildlife depends on. And burning ever more fossil fuels to power it all pumps extra carbon dioxide into the atmosphere, strengthening the enhanced greenhouse effect and nudging the climate. Each impact is tangled up with the others — they're all downstream of that same growing total demand.

So what's the response? It's captured in one word: stewardship — using and managing natural resources responsibly today so that future generations still inherit enough to meet their own needs. The goal stewardship aims at has a name too, sustainability: living in a way that meets today's needs without wrecking tomorrow's ability to do the same. It's the difference between spending only the interest and devouring the entire savings account — a way of using the Earth that could, in principle, go on indefinitely.

Stewardship isn't just a nice idea; it shows up in specific, practical strategies. Conservation means simply using less, or using it more efficiently — think LED bulbs, insulated homes, and shorter showers. Recycling and reusing materials cut how much brand-new resource has to be mined or drilled in the first place. Switching to renewable energy eases our draw on fossil fuels. Setting sustainable harvest limits — fishing quotas that let a fish population rebuild, or rotating crops to keep soil healthy — takes only what nature can replace. Protecting habitats and monitoring the environment with science-based policy round out the toolkit.

Watershed stewardship can protect water quality by managing land cover, runoff and pollutant inputs, alongside appropriate treatment and monitoring. Protecting a watershed does not guarantee that every contaminant is removed or that treatment is unnecessary. Evaluate actual water-quality measurements, supply conditions and the function of each protection or treatment process before claiming that a drinking-water system is safe or fully restored.

Human activities alter land cover, water flow, habitats and atmospheric composition. A local observation needs a baseline and a comparison to show the size and timing of change. Consider natural variability and other possible causes alongside the proposed mechanism.

Stewardship decisions combine evidence with goals and constraints. Protecting one habitat, reducing runoff or supplying a community's needs can involve competing priorities. State whose needs and which environmental measures are included rather than hiding the trade-offs.

Evaluate an intervention with measurable outcomes before and after, comparable controls and repeated observations. A short improvement may not persist through a different season. Monitoring and revision are part of a scientific design process, not signs that planning was pointless.

Total Resource Demand

total demand = population × per-capita consumption

population is the number of people and per-capita consumption is the average amount each person uses; if either factor grows, total demand grows, and the two effects multiply together.

Worked examples

Avoid these mistakes

• A single before-and-after measurement rarely isolates the cause of a change.

Words to know

stewardship

Using and managing natural resources responsibly so that future generations can still meet their own needs.

sustainability

Meeting the needs of people today without ruining the ability of future generations to meet their own needs.

conservation

Using less of a resource, or using it more efficiently, to make it last longer and reduce waste.

per-capita consumption

The average amount of a resource used by one person; total demand depends on population size and per-capita consumption together.

IPAT: a formula for total environmental impact

Scientists sometimes formalize the population-times-consumption idea in this lesson into a slightly bigger equation called IPAT: Impact = Population × Affluence × Technology. Affluence represents consumption per person (as in this lesson), while Technology represents how efficiently or wastefully that consumption happens — meaning technology can push impact in either direction. A more efficient car, a recycling program, or a solar panel are all examples of technology reducing environmental impact even while population and affluence keep rising, which is why the 'T' term is where most modern stewardship strategies try to make a difference.

Earth Overshoot Day: a global bank account running a deficit

Each year, scientists calculate a date called Earth Overshoot Day — the day when humanity's total demand for ecological resources and services in that year exceeds what Earth's ecosystems can regenerate in that same year. In the 1970s, that date fell around December, meaning humanity used roughly a full year's worth of resources. Today, Earth Overshoot Day typically falls in early August, meaning humanity is using the resource-generating capacity of roughly 1.7 Earths every year — effectively spending down savings that took nature millennia to accumulate.

The tragedy of the commons: why shared resources get overused

Some resources — ocean fisheries, clean air, groundwater aquifers — aren't owned by any single person, which creates a dangerous pattern economists call the tragedy of the commons: each individual user benefits personally from using more, while the cost of depletion is spread across everyone, so no one has a strong individual incentive to hold back. A single fishing boat catching a few more fish barely dents the total population, but if every boat reasons the same way, the shared fish population can collapse. This is exactly why effective stewardship (like fishing quotas) usually requires collective rules, not just individual good intentions.

Biomagnification: pollution that gets stronger up the food chain

Human impact isn't limited to using up resources — it also includes pollutants that become more concentrated as they move up a food chain, a process called biomagnification. A pollutant like mercury might exist at barely measurable levels in water, but small organisms absorb it, slightly larger fish eat many of those small organisms and accumulate their mercury too, and top predators (including humans, in some fish-heavy diets) end up with far higher concentrations than what started in the water. It's a reminder that environmental harm doesn't always look like an obvious oil spill — sometimes it quietly climbs an entire ecosystem.

The Hudson River's decades-long PCB cleanup

From the 1940s through the 1970s, General Electric plants released an estimated 1.3 million pounds of toxic PCB chemicals into the upper Hudson River, contaminating sediment for over 200 miles downstream and leading to fishing bans that in some stretches still exist today. Declared a federal Superfund site, the Hudson became the focus of one of the largest and most expensive river dredging cleanups in U.S. history, removing contaminated sediment from the riverbed over more than a decade of work. It's a real, local case study of both the lasting cost of pollution and the difficult, expensive work stewardship sometimes requires to undo it.

In the real world

Curbside recycling and composting programs in Westchester towns are everyday examples of stewardship, reducing how much new material must be mined or manufactured.

Exit check

What makes an environmental proposal testable rather than only an opinion?

Evaluating Environmental Solutions

Learning goals

• I can compare solutions using evidence, criteria, and constraints.
• I can calculate a reduction in resource demand and explain its limits.

Readings for this unit

• A design decision that people can inspect and revise

An environmental design problem starts with a clear goal and system boundary. A town may want to reduce stormwater runoff, protect drinking water, or lower energy demand. Criteria describe success; constraints set limits such as cost, space, maintenance, and time. Stakeholders can value different outcomes.

Compare alternatives over the same task and time interval. A percentage reduction needs a baseline: reduction = (original − new) ÷ original × 100%. Account for effects moved elsewhere, such as manufacturing energy or disposal impacts. A local improvement does not automatically establish the best whole-system outcome.

Use evidence to justify a choice, test a prototype or model, and revise. Report uncertainties and trade-offs. A solution may reduce vulnerability or pollution without eliminating the underlying hazard or meeting every goal. Monitor outcomes after implementation and identify what would make you change your recommendation.

Define success before comparing solutions. For a flood-control plan, useful criteria might include peak runoff, habitat effects, maintenance and cost. A design that performs well on one criterion can perform poorly on another.

Compare alternatives under equivalent conditions and include uncertainty. Small model basins can test mechanisms but omit actual soil layers, drainage networks and extreme storms. Distinguish a classroom prototype result from a claim about a full town.

A defensible recommendation presents evidence, limitations and a plan to monitor outcomes. Explain why the chosen criteria matter and what result would cause a revision. Sustainability includes long-term resource and ecological effects, not only the lowest purchase price.

Worked examples

Avoid these mistakes

• The cheapest design is not automatically the most effective or sustainable.

Words to know

criterion

A measure of success for a design.

constraint

A limit the design must satisfy.

life-cycle perspective

Considering impacts across production, use, and end-of-life stages.

In the real world

Exit check

What result would justify revising an environmental design recommendation?