Earth Day
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8correct to beat the crowd
This environmental trivia quiz has 49 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 49 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 02Who is considered the founder of Earth Day?
Gaylord Nelson
Gaylord Nelson, a U.S. senator from Wisconsin, proposed Earth Day after seeing a huge 1969 oil slick from an airplane, borrowing the teach-in format from the anti-war movement; he hired 25-year-old Denis Hayes to organize it.
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, under Nixon's Reorganization Plan No. 3, which pulled pollution programs together from several departments; William Ruckelshaus was its first administrator.
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. The United Auto Workers were the biggest outside backer; organizer Denis Hayes said that without the union the day 'would have likely flopped'.
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, signed on December 31, set the first national air-quality standards and gave the federal government primary responsibility for enforcing them; the water and endangered-species laws followed in 1972 and 1973.
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, on January 28, 1969; the 800-square-mile slick was visible from the air, and the first anniversary was marked locally 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 11What is the primary greenhouse gas responsible for human-caused climate change?
Carbon dioxide
Water vapour is more abundant, but it responds to temperature rather than driving it; CO2 from fossil fuels has risen more than 50% since 1750.
Q 12The Paris Agreement, a landmark climate accord, was adopted in what year?
2015
The Paris Agreement was adopted by consensus at COP21 in Paris on 12 December 2015; it aims to hold warming well below 2 degrees Celsius above pre-industrial levels.
Q 13What does the term 'carbon footprint' refer to?
All greenhouse gases an activity adds to the air
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 23Of the 62 million tonnes of e-waste generated in 2022, what share was formally recycled?
It is usually expressed in tonnes of CO2-equivalent and counts indirect emissions, such as the energy used to make the goods you buy, alongside direct ones like driving.
Q 14Which teenager became world-famous for her school climate strikes starting in 2018?
Greta Thunberg
Greta Thunberg began her 'Fridays for Future' school strikes outside the Swedish parliament in August 2018 at age 15. Her solitary protest sparked a global youth climate movement involving millions of students worldwide.
Q 15What is the 'greenhouse effect'?
Heat-trapping gases keeping a planet warm
The greenhouse effect is heat-trapping gases such as water vapour and CO2 keeping a planet warm; without it Earth's average surface temperature would be about minus 18 degrees Celsius instead of roughly 15.
Q 16Which layer of Earth's atmosphere contains the ozone layer that protects us from UV radiation?
Stratosphere
The ozone layer lies in the stratosphere, roughly 15 to 35 kilometres up, and absorbs most of the Sun's ultraviolet radiation, which is what made life on land possible.
Q 17The Montreal Protocol, signed in 1987, phased out which class of chemicals?
Chlorofluorocarbons
CFCs from aerosols and refrigerants were eating a hole in the ozone shield. The treaty is often called the most successful environmental agreement ever adopted, and the layer is now recovering.
Q 18What was the approximate concentration of CO2 in Earth's atmosphere in 2023?
420 parts per million
Atmospheric CO2 averaged about 420 parts per million in 2023, up more than 50% from the roughly 280 ppm that held for the 10,000 years before the Industrial Revolution, and the highest in at least 800,000 years.
Q 19Which gas from livestock and rice paddies has about 80 times CO2's warming power over 20 years?
Methane
It breaks down within about a decade, so its punch is front-loaded; livestock digestion, rice paddies, landfills and gas leaks are the big sources.
Q 20What does 'net zero' mean in the context of climate goals?
Emissions balanced by an equal amount removed
Net zero means emissions are balanced by an equal amount removed from the air, whether by planting trees or direct air capture; once that balance is reached, further warming is expected to slow sharply.
Roughly a fifth
Only about 22%, roughly a fifth, was documented as formally collected and recycled; the rest was dumped, burned or informally stripped, often in poorer countries, despite the gold, copper and rare earths inside it.
Q 24What percentage of the Earth's surface is covered by oceans?
About 71%
Oceans cover about 71% of Earth's surface and hold 97% of the planet's water, yet by 2023 only about a quarter of the seafloor had been mapped in high resolution.
Q 25What is ocean acidification?
Seawater absorbing CO2 and its pH falling
Ocean acidification is seawater absorbing CO2 from the air and its pH falling: between 1950 and 2020 the average surface pH dropped from about 8.15 to 8.05, which threatens corals and shellfish that build carbonate shells.
Q 26Which environmental hazard did the 2024 Global Burden of Disease Study link to 8.1 million deaths in 2021?
Air pollution
Air pollution was the hazard: outdoor fine particulates were the biggest killer at 4.7 million deaths, followed by household smoke from cooking and heating fuels at 3.1 million, with ozone adding about half a million.
Q 27What is 'e-waste'?
Discarded electrical or electronic devices
E-waste is discarded electrical or electronic devices, from phones to fridges; it is one of the fastest-growing waste streams on Earth, driven by ever-shorter device lifespans, and most of it is never formally 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, roughly 4,200 terawatt-hours, ahead of wind at about 8% and solar at about 5.5%, and more than nuclear.