Ecosystems, resources, pollution and climate, with the unit conversions environmental questions need.
Environmental science combines biology, chemistry, earth science and economics to study how natural systems work and how human activity changes them. Topics include ecosystems and energy flow, biogeochemical cycles, population growth, land and water use, energy resources, pollution and climate.
The subject is strongly quantitative. Students calculate energy transfer between trophic levels (often about 10% at each step), population doubling time with the rule of 70, percent change in emissions and the cost of energy alternatives. Data analysis and unit conversion appear in almost every free-response question.
Environmental scientists work in conservation, water management, energy planning, consulting and government policy. The same calculations are used by anyone comparing the running cost of appliances, cars or heating systems, or judging claims about emissions and sustainability.
Earth systems and human impact. (High school)
An ecosystem is a community of living things together with its physical environment, linked by flows of energy and cycles of matter. Energy enters mostly as sunlight captured by producers, passes to consumers through food chains and food webs, and leaves as heat. Matter, such as carbon and nitrogen, cycles and is reused.
Population ecology studies how the number of individuals of a species changes over time. With unlimited resources a population grows exponentially, , doubling in a fixed time. Real environments run short of food, space and other resources, so growth slows as the population approaches the carrying capacity .