145 Fun Facts About Climate Change

Which greenhouse gas, far more abundant than carbon dioxide, has its level set by temperature rather than emissions?

Water vapor does about half of all the atmosphere's heat-trapping, but because warmer air holds more of it, it amplifies warming that other gases start rather than causing it.

Which 1997 treaty committed industrialized countries to reduce greenhouse gas emissions?

The Kyoto Protocol was signed by the Clinton administration in 1998 but never sent to the Senate for ratification, and the treaty did not enter into force until 2005.

At which Hawaiian observatory has CO2 been measured continuously since 1958, producing the Keeling Curve?

Mauna Loa was chosen because the high, remote volcano is far from continents and has little vegetation, so its air reflects the well-mixed atmosphere rather than local pollution.

What is the largest human activity contributing to rising atmospheric carbon dioxide levels?

Burning fossil fuels is the leading cause, and scientists can prove it: fossil carbon contains no radioactive carbon-14, and the air's share of that isotope has been falling as CO2 climbs.

What natural process has atmospheric gases trap heat and warm Earth's surface?

The greenhouse effect was measured in the laboratory by John Tyndall in 1859; Swedish meteorologist Nils Gustaf Ekholm attached the greenhouse name to it in 1901, decades after the physics had been worked out.

Which potent greenhouse gas persists in the atmosphere for only about 12 years?

Methane traps far more heat than CO2 while it lasts but breaks down in about 12 years, so cutting its emissions is one of the quickest ways to slow warming within a couple of decades.

Which scientist showed in an 1856 paper that CO2 absorbs heat and could alter climate?

Eunice Newton Foote's 1856 paper found that a glass cylinder filled with carbon dioxide heated far more in sunlight than one of ordinary air, three years before John Tyndall's better-known experiments.

Which scientist first quantitatively predicted, in 1896, the warming from doubling atmospheric CO2?

Svante Arrhenius was really trying to explain what had caused the great glaciations; he later suggested that industrial emissions might spare the world a new one and help feed a growing population.

Besides melting land ice, what is the other main cause of global sea level rise?

Thermal expansion: water swells as it warms, and the ocean has soaked up more than 90% of the excess heat trapped by greenhouse gases, enough to cause nearly half of the rise in recent decades.

What do scientists call the ocean's chemical shift caused by absorbing excess carbon dioxide?

Ocean acidification leaves fewer carbonate ions in seawater, so oysters, clams and tiny plankton struggle to build their shells, which in the worst cases begin to dissolve.

Which climate policy sets a fixed ceiling on emissions and lets firms exchange permits?

Cap and trade got its first national test in 1995, when American power plants began trading sulfur dioxide permits under a scheme to cut the pollution behind acid rain.

Which impact on marine ecosystems occurs when heat-stressed animals expel the colourful algae living in their tissues?

Coral bleaching leaves the animals white and hungry, because the expelled algae were feeding them; they can recover if the water cools, but a long heatwave kills the reef.

What term do climate scientists use for action to cut greenhouse gas emissions or boost the sinks that absorb them?

Climate Mitigation keeps getting cheaper: once hopelessly expensive, onshore wind and solar panels had by 2020 become the cheapest ways to generate new electricity in many regions.

What term describes ground frozen for at least two consecutive years, which releases carbon as it thaws?

Permafrost holds about twice as much carbon as the atmosphere; when it thaws, microbes digest plant remains frozen for thousands of years and release that carbon as heat-trapping gases.

Which feedback loop amplifies warming as bright surfaces give way to darker land and water?

Ice-albedo feedback: snow-covered sea ice reflects up to 90% of sunlight while open ocean absorbs about 94%, a big reason the Arctic has warmed nearly four times faster than the globe since 1979.

Parts of which rainforest now release more carbon than they absorb, a 2021 study in the journal Nature found?

The Amazon's south-east, the section hit hardest by deforestation and fire, has flipped from soaking up carbon to giving it off, a reversal for a forest long counted on as a brake on warming.

Which kind of extreme weather has grown more frequent and intense over most land since the 1950s?

Heavy downpours are getting heavier because air holds about 7% more moisture for every degree Celsius it warms, so each storm has more water to shed.

What is the term for capturing atmospheric carbon dioxide and storing it long-term in forests, soils or rock?

Carbon sequestration happens naturally on a vast scale: plant growth and the oceans together remove about half of the CO2 that humans emit, and only the rest stays in the air.

Which 2015 treaty, adopted at COP21, aims to keep global warming well below 2 °C above pre-industrial levels?

The Paris Agreement lets each country set its own emissions pledge instead of imposing targets, but requires a new, more ambitious pledge every five years.

Which synthetic gas, used to insulate high-voltage switchgear, is the most potent greenhouse gas the IPCC has assessed?

Sulfur hexafluoride traps more than 20,000 times as much heat as CO2 and lingers for many centuries, so every leak from the power grid is effectively permanent.

Which two United Nations bodies set up the Intergovernmental Panel on Climate Change in 1988?

WMO and UNEP, the UN's weather and environment agencies, founded the panel, which does no research of its own: thousands of scientists volunteer to assess the published studies instead.

Which planet's thick carbon dioxide atmosphere traps so much heat that its surface is hot enough to melt lead?

Venus is the hottest planet, around 465 °C at the surface, even though Mercury orbits much closer to the Sun; scientists study it as a warning of runaway warming.

Which nation has released the most cumulative carbon dioxide since the Industrial Revolution?

The United States has emitted roughly a quarter of all fossil-fuel CO2 since 1850, more than any other nation; China overtook the US in annual emissions only around 2006.

What term describes the total greenhouse gas emissions caused by a person, product, organisation or country?

Carbon footprint went mainstream thanks to an oil company: BP's advertising in the mid-2000s promoted a personal calculator, which critics say shifted the blame onto individuals.

What name is given to a home or office that generates as much renewable power over a year as it uses?

A zero-energy building is no longer a niche idea: since the end of 2020, European Union rules have required every new building to be 'nearly zero-energy'.

Which process, in effect the reverse of photosynthesis, do plants, animals and microbes use to turn sugars back into carbon dioxide?

Cellular respiration never stops, so each northern winter, when plant growth stalls, the CO2 in the air climbs for months until summer leaves pull it back down.

Which scientist's June 1988 Senate testimony raised broad public awareness of global warming?

James Hansen, then director of NASA's Goddard Institute for Space Studies, told a Senate committee on 23 June 1988 that he was 99 percent confident the warming trend was real and not a chance fluctuation.

What are the numerical simulations coupling atmosphere, ocean, land and ice to project Earth's future called?

Climate Models have a solid track record: a 2020 review of 17 projections published between 1970 and 2007 found that most had accurately predicted the warming that followed.

What technology captures CO2 from a point source and injects it into deep geological formations?

Carbon capture and storage began at scale in 1996 at the Sleipner gas field in the North Sea, where burying the CO2 under the seabed proved cheaper than paying a carbon tax brought in five years earlier.

Half of all species with long-term records have shifted their ranges in which direction, the IPCC reported in 2022?

Poleward, or uphill on mountains, as species follow the temperatures they are adapted to; where they could not keep up, heat extremes have already wiped out hundreds of local populations.

What term describes adjusting to a warming world's effects, rather than trying to prevent them?

Climate adaptation ranges from flood barriers to drought-tolerant crops; among the cheapest steps is a storm early-warning system, since just 24 hours' notice can cut the damage by up to 30%.

What name is given to the idea that those who did least to cause global warming suffer its worst effects?

Climate justice starts from a stark imbalance: between 1990 and 2015 the richest 1% of people caused more than twice the carbon emissions of the poorest half of humanity.

Which farming approach aims to restore degraded soils, boost biodiversity and store carbon?

Regenerative agriculture relies on cover crops and leaving soil unploughed; experts agree it improves soil health, but how much carbon it can really lock away is disputed.

What financial instrument specifically funds projects with environmental or climate benefits?

Green bonds began with a phone call: in late 2007 Swedish pension funds asked the World Bank how to invest in climate projects, and a year later it issued the first bond of that name.

Which long-lived greenhouse gas is released when soil microbes feed on the nitrogen fertiliser spread on farmland?

Nitrous oxide, the dentist's 'laughing gas', lingers in the air for more than a century and also attacks the ozone layer: it is now the largest ozone-destroying emission from human activity.

Records kept in Japan since 812 show which annual event now arriving earlier than ever?

Cherry blossom in the old capital peaked in mid-April in the 1850s and now peaks around the start of April, as warmer springs pull the season forward; biologists call such changes phenological shifts.

Roughly what fraction of humanity's carbon dioxide emissions has the ocean absorbed?

The ocean has taken up about a quarter of human CO2 emissions, roughly 2.5 billion tonnes of carbon a year, which drives the steady fall in surface seawater pH.

What phenomenon makes built-up city centres significantly warmer than the surrounding countryside?

Urban Heat Island: concrete, asphalt and dark roofs soak up the sun all day and give the heat back after dark, which is why the gap with the countryside is widest at night.

For the 10,000 years before the mid-18th century, atmospheric CO2 stayed at roughly what level?

About 280 ppm held through the 10,000 years to the mid-1700s; ice cores show the level stayed between 180 and 280 ppm for 800,000 years, until the rise of the last 250 years.

What term refers to the fraction of solar radiation a surface reflects back into space?

Albedo quantifies the reflectivity of a surface, indicating the percentage of incoming solar radiation that is reflected back into space. Surfaces like snow and ice have high albedo, while oceans and forests have low albedo.

Which 1987 treaty phasing out ozone-depleting substances has been ratified by every country?

The Montreal Protocol was written to save the ozone layer, but its 2016 Kigali Amendment, which phases down the refrigerant gases that replaced CFCs, should also avoid up to 0.5 °C of warming by 2100.

What is the goal where heat-trapping gases from human activity are balanced by removals called?

Net-zero emissions is the target because warming is expected to stop soon after the world reaches it; until then, every extra tonne of CO2 pushes temperatures higher.

In climate science, what term describes a critical threshold that, once crossed, leads to large, accelerating and often irreversible change?

A Climate Tipping Point may be closer than once thought: a 2022 study in Science found that the West Antarctic ice sheet and tropical coral reefs could pass theirs at about 1.5 °C of warming.

What is planting a new forest on land not forested for a significant period called?

Afforestation's boldest test is Africa's Great Green Wall, a plan to green 100 million hectares south of the Sahara by 2030; a 2020 progress report found just 4% of the target covered.

What is the degradation of productive dryland into barren, unproductive terrain called?

Desertification is less a march of dunes than a loss of plant cover: once overgrazing, firewood cutting and drought strip the ground, wind and flash floods carry the bare topsoil away.

Which 1992 treaty, opened for signature at the Rio Earth Summit, frames global greenhouse gas talks?

The UNFCCC is why there is a 'COP' summit every year: its parties first met in Berlin in 1995, in talks chaired by Germany's environment minister, Angela Merkel.

Which natural process returns the carbon in fallen leaves and dead wood to the air, and speeds up as soils warm?

Decomposition by microbes and fungi returns carbon from dead matter to the air as CO2; it accelerates in warmth, one reason thawing northern soils are giving up carbon stored for millennia.

Which French mathematician first proposed in the 1820s that the atmosphere acts as an insulator?

Joseph Fourier worked out that a planet at Earth's distance from the Sun ought to be far colder, and compared the atmosphere to the glass lid of a box that lets sunlight in but holds heat.

Which oil company's own scientists predicted global warming with 'shocking skill and accuracy' from the late 1970s, a 2023 study found?

Exxon's in-house projections between 1977 and 2003 matched the warming that followed, even as the company spent years publicly casting doubt on the science.

What sporting nickname was given to the 1999 Mann, Bradley and Hughes temperature graph?

Hockey stick: the long flat shaft is centuries of slow cooling and the blade the sharp 20th-century upturn; asked by Congress to review it in 2006, the US National Research Council found its main conclusion plausible.

Emails hacked from which university's Climatic Research Unit sparked 'Climategate' in 2009?

East Anglia's Climatic Research Unit was the target; a string of official inquiries, including ones led by Sir Muir Russell and Lord Oxburgh, found no evidence of scientific malpractice.

Which 2006 climate documentary won the Oscar for Best Documentary Feature?

An Inconvenient Truth made its presenter the face of the issue: the year after its release, Al Gore shared the Nobel Peace Prize with the UN's panel of climate scientists.

Outside which building did Greta Thunberg begin her school strike in August 2018?

Thunberg sat outside the Riksdag, Sweden's parliament, from 20 August 2018, intending to strike only until the general election three weeks later, after Sweden's hottest summer in at least 262 years.

The 2021 Glasgow Climate Pact was the first COP deal to explicitly commit to reducing which fuel?

The Glasgow pact pledged to 'phase down' unabated coal power, the first explicit mention of coal in a COP decision; late interventions from India and China softened the wording from 'phase out'.

COP28 in 2023, the first to call for a shift away from all fossil fuels, was held in which city?

COP28 met at Expo City Dubai in December 2023 and agreed to 'transition away from fossil fuels'; its president, Sultan Al Jaber, was simultaneously chief executive of the Abu Dhabi National Oil Company.

Which fund for climate-vulnerable countries was agreed for the first time at COP27 in Egypt?

The loss and damage fund crowned three decades of pressure from vulnerable nations, which first asked for such help in 1991; agreed at COP27, it was formally launched on the opening day of COP28.

The US withdrawal from the 2015 global climate treaty took effect the day after which 2020 event?

The exit took effect on 4 November 2020, the day after the presidential election: the treaty barred any withdrawal notice for three years after it came into force, then imposed a one-year wait.

Which 2022 US law made the largest investment against greenhouse gas emissions in American history?

The Inflation Reduction Act, signed in August 2022, put about $391 billion into energy and climate measures; it was the much-reduced survivor of the far larger Build Back Better plan.

Ursula von der Leyen called which EU plan Europe's 'man on the moon moment'?

Von der Leyen used the phrase when unveiling the European Green Deal on 11 December 2019; Poland secured an exemption from the 2050 climate-neutrality commitment when the European Council backed the plan days later.

Which economist led the 700-page 2006 review of climate change economics for the UK government?

Nicholas Stern's review called climate change the greatest market failure ever seen and put the cost of doing nothing at 5% or more of global GDP every year, against about 1% to act.

Which group of countries campaigned from 2008 for a 1.5 °C limit on global warming?

Small island states pressed for 1.5 °C when bigger powers favoured 2 °C, and their long campaign helped win the lower limit a place in the 2015 climate treaty.

The change in Earth's energy balance caused by CO2 or aerosols is measured in which unit?

Radiative forcing is expressed in watts per square metre; the IPCC's Sixth Assessment put total human-caused forcing at 2.72 W/m² in 2019 relative to 1750, with aerosol cooling partly offsetting the gases.

Milankovitch cycles in Earth's orbit and tilt pace which recurring events?

Ice ages follow the slow stretching, tilting and wobbling of Earth's orbit; the Serbian scientist Milutin Milanković worked out the sums a century ago, decades before seabed cores confirmed them.

In the bitter winters of centuries past, 'frost fairs' with stalls, dancing and even an elephant were held on which frozen river?

The Thames hosted its last frost fair in February 1814, late in a run of colder centuries; an elephant was led across by Blackfriars Bridge, and the river in London has never frozen hard enough to hold another.

Syukuro Manabe and Klaus Hasselmann shared which 2021 Nobel Prize for modelling Earth's climate and predicting global warming?

Physics: the committee honoured Manabe's 1960s models showing how extra CO2 warms the surface, and Hasselmann's method for picking out the human fingerprint in the climate record.

Which Antarctic ice shelf, about the size of Rhode Island, shattered in little more than a month in 2002?

Larsen B lost 3,250 square kilometres of ice in just over a month, faster than scientists had ever seen; with the shelf no longer bracing it, a glacier behind sped up threefold.

Which Antarctic glacier, larger than Florida, has been nicknamed the 'Doomsday Glacier'?

Thwaites Glacier in West Antarctica is about 120 km across, the widest on Earth, and holds enough ice to raise global sea level by around 65 cm, with more to follow if it destabilises its neighbours.

Which Arctic landmass holds enough ice to raise global sea levels by about seven metres if it all melted?

Greenland's ice sheet, up to three kilometres thick, would add about 7.4 m to the oceans, against some 58 m for Antarctica's; even in a hot future, melting all of it would take at least a thousand years.

Which country's president held the world's first underwater cabinet meeting in October 2009?

Maldives president Mohamed Nasheed and his ministers, in scuba gear on the sea bed, conferred by hand signals and white boards, then signed a call for global emissions cuts ahead of the Copenhagen summit.

Which Pacific nation's foreign minister recorded his COP26 speech standing knee-deep in the sea?

Tuvalu's Simon Kofe used the moment to press a plan for the worst case: if the islands vanish, the country means to live on as a 'digital nation', keeping its statehood and sea borders.

The April 1815 eruption of which volcano caused 1816's 'Year Without a Summer'?

Mount Tambora's ash and gases dimmed the Sun worldwide and killed crops across Europe and North America; the gloom kept Mary Shelley indoors at Lake Geneva, where she began Frankenstein.

Which country recorded almost 15,000 deaths in the August 2003 European heat wave?

France counted 14,802 heat deaths; with families and doctors away for the August holidays, hundreds of bodies lay unclaimed for weeks.

Scientists gauge the limit of human heat tolerance using which measure of heat and humidity?

Wet-bulb temperature of 35 °C was long taken as the survival limit; lab tests on young, healthy volunteers have since put the real threshold lower, at about 31 °C.

The Bramble Cay melomys, declared extinct after vanishing from its Great Barrier Reef island, was what kind of animal?

The melomys was a rodent, a mosaic-tailed rat last seen in 2009; with its low cay repeatedly swamped by rising seas, it is thought to be the first mammal wiped out by man-made climate change.

The golden toad, last seen in 1989, lived in the cloud forest above Monteverde in which country?

Costa Rica's golden toad vanished fast: about 1,500 gathered to breed in 1987, and two years later a lone male was the last ever seen; scientists still argue over whether a warming climate or a fungus was to blame.

Whose carbon market, set up in 2005, was the world's first major one for greenhouse gas permits?

The EU's market had a rocky start: governments handed out more permits than firms needed, and by 2007 the price of emitting a tonne of CO2 had fallen almost to zero.

Which country's Climate Change Act of 2008 set the world's first legally binding national emissions target?

Britain's law began with an 80% cut by 2050, raised from the 60% in its first draft; in 2019 the target was tightened again, to net zero.

Citizens of which low-lying country won the landmark Urgenda case, forcing their government to cut emissions faster?

The Netherlands lost in its own Supreme Court in 2019: judges ruled that protecting citizens' human rights required a 25% emissions cut by the end of 2020, a verdict that inspired lawsuits from Pakistan to New Zealand.

Climeworks' Orca plant, which pulls CO2 from the air and stores it in rock, opened in 2021 where?

Iceland supplies what the plant needs: geothermal power from the Hellisheiði station next door, and basalt bedrock in which the injected CO2 turns to stone within about two years.

Which waterlogged landscapes cover about 3% of land yet hold more carbon than all the world's forests?

Peatlands lock away dead plants that never fully rot; drain or burn them and the carbon escapes, which is why damaged peat, on less than half a percent of the land, causes about 5% of human greenhouse emissions.

Making which building material releases CO2 from the limestone itself, accounting for about 8% of global emissions?

Cement would rank as the world's third-largest emitter if its industry were a country; much of the CO2 comes from the chemistry of baking limestone, so cleaner fuel alone cannot fix it.

Which side effect of jet exhaust warms the climate more than aviation's CO2?

Contrails spread into thin, heat-trapping cloud, which is why flying has caused about 4% of global warming to date while producing only about 2.5% of the world's CO2 emissions.

What is the digestive process, driven by microbes in a cow's first stomach, that makes the heat-trapping gas cattle belch?

Enteric fermentation happens at the front end of the animal, so, contrary to the old joke, most of the gas leaves as burps rather than from the rear.

Whose scientists first reported the ozone hole in 1985, from readings at Halley station?

The British Antarctic Survey's Joe Farman and colleagues published only once they were sure the drop was real: year after year, the springtime readings had been 'falling off the graph'.

Which engineer developed both leaded gasoline and the first CFCs, sold under the name Freon?

Thomas Midgley Jr. found the lead additive in 1921 while working under Charles Kettering at General Motors, then led the team that made the first CFC; both inventions were later banned for the harm they did.

The Senate's 95–0 Byrd–Hagel Resolution of 1997 opposed any climate treaty that exempted which group of countries?

Developing countries stayed the sticking point: in 2001 President Bush cited the same 95–0 vote when he rejected the treaty, saying it exempted 80 percent of the world, including China and India.

Which country in 2011 became the first to announce its withdrawal from the 1997 emissions treaty?

Canada's environment minister Peter Kent announced the withdrawal on 12 December 2011, saying staying in would have cost $14 billion in penalties; the exit took effect in December 2012.

Wallace Broecker, who popularised the phrase 'global warming' in 1975, likened the world's deep-sea circulation to which machine?

A conveyor belt carrying heat around the planet was Broecker's image for the linked flow of the world's seas; he also called the climate system 'an angry beast' that humanity keeps poking.

The 2004 film The Day After Tomorrow depicts a new ice age triggered by the disruption of what?

Atlantic Ocean currents could genuinely weaken as the planet warms, scientists say, but over decades to centuries; the film squeezes the collapse and a new ice age into about a week.

In 2020 which country became the first where all-electric cars outsold all combustion-engine cars?

Norway: battery-electric cars took 54% of its new-car market in 2020, up from about 1% a decade earlier, because the oil-rich country spares them the heavy taxes it puts on petrol and diesel models.

Which sinking megacity was chosen in 2019 to be replaced as a national capital by Nusantara, a new city on Borneo?

Jakarta is sinking by up to 25 cm a year in places, largely because so much groundwater is pumped from beneath it, so the sea is rising against a city that is itself going down.

MOSE, a mobile flood barrier first raised against a high tide in 2020, protects which city?

Venice's MOSE barrier, 78 hinged gates lying on the seabed, kept St Mark's Square dry on 3 October 2020; it arrived years late, after repeated delays, cost overruns and scandals.

Peruvian fishermen named the warm Pacific current that arrives each December after whom?

The Christ Child: the current is El Niño, 'the boy', short for El Niño de Navidad, because it showed up around Christmas; its cool counterpart La Niña was once also called El Viejo, 'the old man'.

Which country is carbon negative thanks to forests that its constitution says must always cover at least 60% of the land?

Bhutan's forests absorb far more carbon dioxide than the small Himalayan kingdom emits, and its exports of hydroelectric power push the balance further into the negative.

Which two Democrats presented the Green New Deal resolution to Congress in February 2019?

Ocasio-Cortez and Markey saw their resolution fall in the Senate weeks later by 57 votes to none, after most Democrats, protesting at a vote held without debate, simply answered 'present'.

Which reptiles are hatching mostly female as beaches warm, because sand temperature sets their sex?

Sea turtles hatch female from warmer sand and male from cooler sand. Around the northern Great Barrier Reef, green turtle populations are struggling to produce males.

Which word did Jay Westerveld coin in a 1986 essay on hotels asking guests to reuse towels?

Greenwashing was his word for notices that claimed to 'save the environment' while mostly saving the hotels laundry costs. It came to cover any misleading eco-friendly claim.

Which president had 32 sun-powered water heaters fitted to the White House roof in 1979?

Jimmy Carter predicted the panels would still be supplying cheap energy in the year 2000. They came down in 1986, under his successor, while the roof was being resurfaced.

Which object did Senator Jim Inhofe toss on the Senate floor in 2015 to dispute global warming?

A snowball, shown in winter, was his evidence that the globe was not warming. That year went on to be the warmest then on record.

Which Van Gogh painting did Just Stop Oil activists splash with tomato soup in London in 2022?

Sunflowers, the fourth version of a series Van Gogh painted in Arles in 1888, was the target. The two protesters then glued their hands to the wall below the painting.

Which African peak, whose snows title a Hemingway story, lost almost 85% of its ice in a century?

Kilimanjaro's ice cover shrank from about 11 square kilometres in 1912 to less than one by 2011. Hemingway's 1936 story about its snows became a film starring Gregory Peck.

Which 2021 Netflix satire uses a planet-killing comet as an allegory for global warming?

Don't Look Up follows two astronomers whose warnings about the comet are shrugged off by politicians and the media. It earned four Oscar nominations, including Best Picture.

Which Arctic animal was listed as threatened under American law in 2008 as its sea ice melted?

Polar bear survival depends on sea ice, the platform from which the animals hunt seals. Since 2006, DNA tests have also confirmed wild hybrids with grizzlies, nicknamed pizzly or grolar bears.

Which youth movement of weekly school walkouts grew from a Swedish teenager's 2018 solo protest?

Fridays for Future spread fast: its global strike of 15 March 2019 drew more than a million students in 125 countries. Pupils skip Friday classes to demand action from political leaders.

Which natural climate archive preserves tiny bubbles of ancient air, some of it 800,000 years old?

Ice cores can be drilled from more than two miles down. The air sealed in their bubbles shows how much carbon dioxide the atmosphere held when the ice formed.

Which veteran science broadcaster addressed the 2021 COP26 summit as its 'People's Advocate'?

David Attenborough, then 95, urged the leaders to act to cut emissions. A year earlier he had narrated A Life on Our Planet, a film he described as his witness statement.

Which pope lamented global warming and urged swift action in the 2015 encyclical Laudato si'?

Francis subtitled the letter 'on care for our common home'. Its title, meaning 'Praise Be to You', comes from the Canticle of the Sun by his namesake, Francis of Assisi.

Which billionaire urged 'getting to zero' in the 2021 book How to Avoid a Climate Disaster?

Bill Gates wrote it after more than a decade of studying global warming and investing in innovations to tackle it. He argues that cleaning up electricity should come first.

Which royal launched the Earthshot Prize, which awards £1 million to each of five winners a year?

Prince William took the name from President Kennedy's Moonshot, the 1960s push to land on the Moon. One of the five categories is 'Fix Our Climate'.

Which actor and UN Messenger of Peace used his 2016 Oscar speech to urge action on global warming?

Leonardo DiCaprio called the crisis 'the most urgent threat facing our entire species' as he accepted Best Actor for The Revenant. That year he also narrated the documentary Before the Flood.

Which South African city braced in 2018 for 'Day Zero', when its taps would be shut off?

Cape Town put off Day Zero by cutting its daily water use by more than half, to around 500 million litres. Strong rains from June 2018 then refilled the dams.

Which country's 2022 monsoon floods killed more than 1,700 people and affected some 33 million?

Pakistan had nearly 900,000 houses destroyed and more than a million livestock killed. Its climate minister called the flooding a 'crisis of unimaginable proportions'.

Which European city hosted the 2009 UN climate summit, which ended in a non-binding accord?

Copenhagen ended with delegates merely voting to 'take note' of an accord drafted by five countries after a day of frantic talks. One campaign group called the summit 'an abject failure'.

Which penguin lost thousands of chicks at Halley Bay three years running after sea ice broke up early?

Emperor penguins raise their chicks on sea ice, so losing it is deadly. A 2023 study warned that vanishing ice could bring catastrophic breeding failure to more than 90% of their colonies.

Which annual WWF event, first held in Sydney in 2007, asks people to switch off their lights?

Earth Hour runs from 8:30 to 9:30 p.m., usually on the last Saturday of March. It grew out of a WWF Australia brief to an advertising agency on engaging people with global warming.

Which protest movement, founded in Stroud in 2018, has a circled hourglass as its symbol?

Extinction Rebellion chose the hourglass to warn that time is running out for many species. Its first major action was to occupy Greenpeace's London offices in October 2018.

Which Pacific pattern, a cooling of equatorial waters, favours busy Atlantic hurricane seasons?

La Niña is Spanish for 'the girl'. In El Niño years the picture flips: Atlantic hurricane seasons are usually quieter while storm activity shifts to the Pacific.

Which country switched on the world's first offshore wind farm, off the town of Vindeby, in 1991?

Denmark put up the 11 turbines in 11 days, and the farm ran for 25 years before it was dismantled. A single offshore turbine had been erected in Swedish waters earlier.

Which Irish physicist, namesake of a light-scattering effect, showed in 1859 how gases trap heat?

John Tyndall found that the atmosphere admits the sun's heat but checks its exit. His interest began in the Alps, where he studied how glaciers move.

Which oil giant's own scientists accurately projected global warming from 1977, a 2023 study found?

ExxonMobil publicly cast doubt on that same science for years. Until 2010 it bought regular newspaper advertorials claiming the matter was unsettled.

What name was given to Australia's 2019–20 bushfire season, which burned over 24 million hectares?

Black Summer fires destroyed more than 3,000 buildings and directly killed 33 people. Smoke from the blazes is estimated to have caused more than 400 further deaths.

Sixteen young plaintiffs won a 2023 ruling against which American state's oil and gas permit rules?

Montana hosted the first constitutional climate lawsuit to reach trial in America. The plaintiffs were aged between 2 and 18 when the case was filed in 2020.

Which country lost a landmark 2024 European human rights case on climate, brought by older women?

Switzerland was found to have violated the European Convention on Human Rights by failing to act adequately on global warming. The women's group, formed by 40 members in 2016, had grown to more than 2,500.

Which insect, freed by milder winters, has ravaged British Columbia's lodgepole forests since 1998?

Mountain pine beetle outbreaks were once kept in check because a few days of extreme cold kill most of the insects. In British Columbia they hit more than 160,000 square kilometres of forest.

Which country's Chacaltaya, once the world's highest lift-served ski area, lost its glacier by 2009?

Bolivia's only ski resort depended on the glacier, which was up to 18,000 years old. Two of the country's main cities rely on Andean meltwater in the dry season.

Which California town was mostly destroyed in 2018 by the Camp Fire, which killed 85 people?

Paradise had been warned in a 2005 state fire plan that it was at risk from just such a wind-driven blaze. The fire destroyed more than 18,000 structures.

Which coolants, adopted in place of ozone-eating CFCs, does the 2016 Kigali Amendment phase down?

HFCs, or hydrofluorocarbons, contain no chlorine and so spare the ozone layer, but they turned out to be powerful heat-trapping gases. The amendment is legally binding.

Which African Union project, adopted in 2007, aims to halt the Sahara's spread across the Sahel?

The Great Green Wall brings together more than 20 countries, from Senegal in the west to Djibouti in the east. Sahel-Saharan leaders first approved the idea in Ouagadougou in 2005.

Ed Hawkins's 2018 climate graphic shows each year's temperature, blue to red, as a row of what?

Stripes turn from blue to red as the planet warms, starting from 1850 on the left. Two years earlier Hawkins had made an animated temperature spiral that went viral.

Which dating method, named in 1928 by astronomer Andrew Douglass, reads past climates from trees?

Dendrochronology grew out of Douglass's hunt for sunspot cycles, which he reasoned would show up in tree rings. He went on to found the Laboratory of Tree-Ring Research in Arizona.

What do meteorologists call a narrow band of airborne moisture, such as the Pineapple Express?

Atmospheric river was coined by two MIT researchers in the early 1990s. Such storms bring up to half of California's yearly rain and snow.

Which African lake, shared by four countries, lost about 90% of its open water in the late 20th century?

Lake Chad's open water shrank from 25,000 square kilometres to about 2,000 as drought gripped the Sahel and its water was diverted.

Which fleet of nearly 4,000 ocean floats, named after a ship in Greek myth, tracks sea temperature?

Argo was named to pair with the Jason satellites, which measure the height of the sea surface from orbit. The floats also record salinity and currents.

Which German word, first used in a 1980 publication's title, names Germany's shift to renewables?

Energiewende means 'energy turnaround', and English writers usually leave it untranslated. Under the policy Germany shut down the last of its nuclear power plants in 2023.

The 1991 eruption of which volcano cooled the planet by about half a degree Celsius for two years?

Pinatubo, in the Philippines, produced the second-largest eruption of the 20th century. It threw more particles into the upper atmosphere than any eruption since Krakatoa in 1883.

Which name, popularised in 2000 by chemist Paul Crutzen, was proposed for an epoch shaped by humans?

Anthropocene had been used in a different sense by Eugene Stoermer in the 1980s. Geology's governing bodies voted in 2024 against making it an official epoch.

The yearly UN climate summits are numbered COPs, as in COP26; what does COP stand for?

Conference of the Parties means a formal meeting of all the countries signed up to a treaty. Any final text of a climate COP has to be agreed by consensus.

Which high-altitude wind band did Wasaburo Oishi detect in the 1920s using balloons near Mount Fuji?

Jet stream research by Oishi went largely unnoticed abroad because he published it in Esperanto. Scientists suspect global warming will gradually weaken the winds.

What name is given to the cold centuries when Londoners held frost fairs on the frozen Thames?

Little Ice Age cold is usually dated from the 16th to the 19th century, though some experts start it around 1300. The Thames frost fairs ran from 1608 to 1814.

Which electric home-heating device moves warmth indoors from outside air instead of generating it?

Heat pump systems give out more warmth than the electricity they use, which makes them more efficient than resistance heaters. In hot weather the same machine can run as an air conditioner.

Which land-use change, often made for farming, is the second-largest human source of CO2?

Deforestation ranks second only to the burning of fuels such as oil and gas. Tree loss and wildfires have also reduced how much carbon the world's remaining forests absorb.

Which former secretary of state became the first American presidential envoy for climate in 2021?

John Kerry, the Democrats' 2004 nominee for the White House, had earlier represented Massachusetts in the Senate for 28 years.

Which phrase was Oxford's Word of the Year for 2019 after its use soared by more than 10,000%?

Climate emergency was defined by Oxford as a situation in which urgent action is required to reduce or halt climate change. Rival dictionary Collins chose 'climate strike' that year.

Which Arctic islands hold the Global Seed Vault, whose entrance flooded in warm, wet weather?

Svalbard's vault keeps backup seeds 130 metres above sea level, more than 100 metres inside a sandstone mountain. The water of October 2016 froze after 15 metres of tunnel and never reached them.

In which Bong Joon-ho film do survivors circle an icy Earth by train after a climate fix backfires?

Snowpiercer imagines a cooling chemical sprayed into the upper atmosphere that works far too well. Chris Evans leads a revolt by the passengers crammed into the tail.