Earth Day
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7correct to beat the crowd
This environmental trivia quiz has 99 free questions with answers and covers the whole green agenda, not just the calendar date. You will get the history of Earth Day itself (who founded it, how many Americans turned out in 1970, and which laws and agencies followed), then the science of climate change, the ozone hole and the Montreal Protocol, recycling and e-waste, coral reefs, deforestation, endangered species and the switch to solar and wind. About a third of the questions are easy enough for a classroom or a family round, and the rest climb toward environmental science stumpers, so it works for Earth Day events, science teachers, eco clubs and pub quizzes alike. Every answer has been checked against a real source and each question shows its citation.
30 of 99 questions with answers and explanations. Play the quiz
Q 01In what year was the first Earth Day celebrated?
1970
The first Earth Day was held on April 22, 1970, with demonstrations at thousands of colleges and schools across the United States; it is widely credited with launching the modern environmental movement.
Q 02Which US senator from Wisconsin is credited with founding Earth Day?
Gaylord Nelson
Gaylord Nelson is said to have been spurred by a vast 1969 oil slick he saw from an airplane; he hired 25-year-old Denis Hayes to turn the idea into a national event.
Q 03Which U.S. federal body began operating in December of the same year as the first Earth Day?
Environmental Protection Agency
The Environmental Protection Agency opened on December 2, 1970, pulling pollution programs scattered across several federal departments into one agency under William Ruckelshaus.
Q 04What date is Earth Day celebrated each year?
April 22
Earth Day falls on April 22; organizers wanted maximum college turnout, so they picked a date between spring break and final exams. Peace activist John McConnell had separately proposed marking the March equinox.
Q 05Approximately how many Americans took part in the first Earth Day?
20 million
About 20 million Americans took part, roughly one in ten at the time; what had been pitched as a campus event filled streets, parks and auditoriums from coast to coast.
Q 06Which landmark environmental law did the U.S. Congress pass in the same year as the first Earth Day?
Clean Air Act
The Clean Air Act of 1970 ordered a 90% cut in pollution from new cars within five years, which is why catalytic converters became standard on American models in 1975.
Q 07Rachel Carson's 1962 book 'Silent Spring' focused on the dangers of what?
Pesticides
Silent Spring documented how pesticides such as DDT poisoned birds and other wildlife; chemical companies attacked the book, but it swayed public opinion and led to a 1972 U.S. ban on agricultural use of DDT.
Q 08In what year did Earth Day go global, with events in over 140 countries?
1990
In 1990 Denis Hayes led a campaign that took Earth Day to 141 countries; some 200 million people took part, giving recycling a huge boost and paving the way for the 1992 Earth Summit in Rio de Janeiro.
Q 09Which oil spill in 1969 is often cited as a catalyst for the first Earth Day?
Santa Barbara, California
Union Oil's Platform A blew out six miles off Santa Barbara, California, in January 1969, killing thousands of seabirds; a year on, locals marked the date as Environmental Rights Day.
Q 10Which U.S. president vetoed the Clean Water Act in 1972, only for Congress to override him?
Richard Nixon
Richard Nixon vetoed the 1972 Clean Water Act over its $24 billion cost, not its goals; Congress overrode him the next day, and he then impounded funds he considered unjustifiable.
Q 11Which 1968 photograph, taken from lunar orbit by Apollo 8's Bill Anders, has been called the most influential environmental picture ever taken?
Earthrise
Earthrise showed a small blue planet above a dead grey horizon on Christmas Eve 1968; less than two years later, millions of Americans turned out for the first Earth Day.
Q 12Which climate accord opened for signing on Earth Day 2016?
Paris Agreement
The Paris Agreement, adopted the previous December, drew 175 signatures at the UN on that first day; enough countries then ratified for it to take force that November.
Q 13Which term covers all the greenhouse gases that a person, product or activity adds to the air?
Carbon footprint
Q 21The three chasing arrows of the universal recycling symbol are folded into what mathematical shape?
Möbius strip
The three arrows form a Möbius strip, a one-sided loop; Gary Anderson, a 23-year-old University of Southern California student, designed it for a 1970 Container Corporation of America contest tied to Earth Day and won a $2,500 scholarship.
Q 22By count, the Great Pacific Garbage Patch consists mostly of what?
Microplastics
Less an island than a soup: microplastics dominate by count, about 94% of an estimated 1.8 trillion pieces, though 92% of the mass is larger objects like ghost nets; a 2018 study put its area at 1.6 million square kilometres.
Q 23Which Olympic Games made its medals from metal recovered from donated mobile phones and other old electronics?
Carbon footprint calculators were popularised by an advertising campaign from the oil company BP in the mid-2000s, which put the spotlight on personal choices rather than producers.
Q 14Which global movement grew out of Greta Thunberg's solo school strike outside Sweden's parliament?
Fridays for Future
Fridays for Future took its name from the weekly strikes she went on to hold; thirteen months after she first sat down alone, its protests drew roughly four million people in a single day.
Q 15What is the 'greenhouse effect'?
Heat-trapping gases keeping a planet warm
Heat-trapping gases keeping a planet warm are no bad thing in themselves: without them Earth's average surface would sit well below freezing, at about minus 18°C instead of roughly 14°C.
Q 16Which layer of Earth's atmosphere contains the ozone layer that protects us from UV radiation?
Stratosphere
The ozone layer sits in the stratosphere, roughly 15 to 35 kilometres up; the ultraviolet it soaks up heats the air, which is why the stratosphere grows warmer with height.
Q 17The Montreal Protocol, signed in 1987, phased out which class of chemicals?
Chlorofluorocarbons
Chlorofluorocarbons from spray cans and fridges were thinning the ozone shield; the treaty became the first ratified by every UN member, and the layer should recover by the 2060s.
Q 18Which graph, named for the chemist who began tracking CO2 on Hawaii's Mauna Loa in 1958, shows its steady climb ever since?
Keeling Curve
The Keeling Curve climbs in a sawtooth: each northern summer growing plants pull CO2 out of the air, and each winter decay hands it back, a little higher every year.
Q 19Which gas from livestock and rice paddies has about 80 times CO2's warming power over 20 years?
Methane
Methane breaks down within about a decade, so its punch is front-loaded: measured over a century, its edge over CO2 shrinks to roughly 30 times.
Q 20What does 'net zero' mean in the context of climate goals?
Emissions balanced by an equal amount removed
Emissions balanced by an equal amount removed, whether by forests or by machines, is the goal; climate models suggest warming largely stops once the world gets there.
Tokyo 2020
Tokyo 2020 ran a two-year collection drive backed by about 90% of Japan's local authorities, and reclaimed enough gold, silver and bronze for all of the Games' roughly 5,000 medals.
Q 24About what share of Earth's surface is dry land?
About 29%
About 29% is land; oceans cover the other 71%, yet as of 2026 barely more than a quarter of the seafloor had been mapped in detail.
Q 25What is ocean acidification?
Seawater absorbing CO2 and its pH falling
Seawater absorbing CO2 and its pH falling by about 0.1 sounds slight, but the scale is logarithmic, and the shift already makes it harder for corals and shellfish to build shells.
Q 26Which environmental hazard did a major 2024 health report link to 8.1 million deaths worldwide in 2021?
Air pollution
Air pollution had moved ahead of tobacco and poor diet to become the second leading risk factor for death, behind only high blood pressure.
Q 27What is 'e-waste'?
Discarded electrical or electronic devices
E-waste is discarded electrical or electronic devices, from phones to fridges; a record 62 million tonnes was thrown out in 2022, and under a quarter was properly collected and recycled.
Q 28Coral bleaching is primarily caused by what environmental stressor?
Rising ocean temperatures
Rising ocean temperatures are the main trigger: heat-stressed corals expel the symbiotic algae that feed and colour them, turning white; they can recover if the water cools soon enough.
Q 29What does the acronym 'PPM' stand for when measuring gases in the atmosphere?
Parts per million
Parts per million means one molecule in every million; the notation is not part of the SI system and is technically ambiguous, yet it remains the standard way to quote atmospheric gas levels.
Q 30Which renewable source generated the most electricity worldwide in 2023?
Hydropower
Hydropower supplied about 14% of the world's electricity in 2023, still more than wind and solar put together; the two were growing so fast that they jointly overtook it in 2024.