Laws & Treaties
This 1970 U.S. law gave the EPA authority to regulate six "criteria pollutants," including ozone, lead, and particulate matter.
What is the Clean Air Act?
Excess nitrogen and phosphorus from fertilizer runoff cause this process, which leads to algal blooms and dead zones.
What is eutrophication?
Pound for pound, this colorless gas from cattle, rice paddies, and landfills traps about 25 times more heat than CO₂ over a century.
What is methane?
Lightning, legumes, and industrial Haber-Bosch all do this — converting N₂ gas into a biologically usable form.
What is nitrogen fixation?
Anthracite, bituminous, and lignite are all grades of this fossil fuel — the dirtiest, with the highest CO₂ emissions per unit of energy.
What is coal?
Phasing out CFCs to heal the stratospheric ozone layer was the goal of this 1987 treaty, often called the most successful environmental agreement ever.
What is the Montreal Protocol?
This colorless, odorless gas from incomplete combustion is the leading cause of indoor air poisoning deaths in the U.S. — and it's why your furnace needs a detector.
What is carbon monoxide?
As atmospheric CO₂ dissolves into seawater, it forms carbonic acid and lowers the pH — making life hard for these calcium-carbonate-shelled critters.
What is ocean acidification?
(accept: shellfish/coral struggle to build shells)
Unlike the other major nutrient cycles, this one has no significant atmospheric component — it moves through rock weathering and is often the limiting nutrient in freshwater systems.
What is the phosphorus cycle?
This nuclear process splits uranium-235 atoms to release energy — not to be confused with what powers the sun.
What is fission?
Passed in 1973, this U.S. law protects threatened and endangered organisms and their critical habitat — the spotted owl is one of its most famous beneficiaries.
What is the Endangered Species Act?
Measured in decibels, this often-overlooked pollutant causes hearing loss in humans and disrupts whale communication and bird mating calls.
What is noise pollution?
When dark Arctic ice melts and exposes darker ocean, more solar energy is absorbed and more ice melts. This self-reinforcing cycle has a name.
What is a positive feedback loop?
Plants pull CO₂ out of the air through this process; animals (and decomposers, and your car) put it back through this opposing one.
What is photosynthesis and (cellular) respiration?
Iceland gets nearly all its electricity and heat from this renewable source, thanks to sitting on the Mid-Atlantic Ridge.
What is geothermal (energy)?
This 1972 U.S. law makes it illegal to dump pollutants into "navigable waters" without a permit, and it's the reason the Cuyahoga River no longer catches fire.
What is the Clean Water Act?
This brownish haze forms when NOx and VOCs react in sunlight — it's the reason L.A. has bad air days and Beijing has worse.
What is photochemical smog?
This temperature-driven phenomenon — not melting glaciers — accounts for roughly half of observed sea level rise so far.
What is thermal expansion?
Transpiration, evaporation, condensation, and precipitation all move H₂O around — but this process, where plants release water vapor through stomata, is often combined with evaporation into one term.
What is evapotranspiration?
These two related drawbacks of solar and wind power — addressed by batteries, pumped hydro, and grid upgrades — are why fossil fuels still dominate baseload power.
What are intermittency and (energy) storage?
This 2015 international agreement asks nations to keep warming "well below" 2°C through voluntary nationally determined contributions — but it has no enforcement mechanism.
What is the Paris Agreement (Paris Climate Accord)?
DDT became the poster child for this phenomenon, in which a toxin's concentration increases at each successive trophic level — devastating bald eagles and ospreys.
What is biomagnification?
At about 419 ppm and rising, this measurement station atop a Hawaiian volcano has produced the iconic "Keeling Curve" since 1958.
What is Mauna Loa (Observatory)?
Burning fossil fuels and clearing forests both transfer carbon from these long-term storage sites into the atmosphere — a fancy word for them, please.
What are (carbon) reservoirs/sinks?
In 2011, this Japanese nuclear plant suffered a meltdown after a tsunami — turning global opinion against nuclear and prompting Germany to phase it out entirely.
What is Fukushima (Daiichi)?