How sunlight helps chlorofluorocarbons destroy the ozone molecules that block solar radiation

Why a Montreal Protocol amendment cut back on the replacements for CFCs

Hydrofluorocarbons were introduced in the 1990s as ozone-safe substitutes for chlorofluorocarbons and hydrochlorofluorocarbons. However, scientists later found that they trap thousands of times more thermal energy in the atmosphere than carbon dioxide does, prompting a 2016 amendment to the Protocol to phase them out.

How scientists earned themselves a Nobel Prize by discovering what destroyed ozone

In 1974, chemists Mario Molina and F. Sherwood Rowland showed that chlorofluorocarbons—then used as aerosol propellants, refrigerants, and industrial solvents—rise into the stratosphere and, upon being struck by ultraviolet radiation, release chlorine atoms, which break apart ozone molecules. Their work earned them the Nobel Prize in chemistry in 1995.

Fluorinated molecules are the most impactful, longest-lasting greenhouse gases

Developed as replacements for ozone-depleting substances in refrigeration and air conditioning systems, these compounds are released through leaks in and ongoing use of these appliances, as well as from various industrial processes. They can remain in the atmosphere for thousands of years and have warming potentials that are a thousand to tens of thousands of times greater than those of carbon dioxide.

Ozone protects against the sun's UV radiation and enhances the greenhouse effect

In the stratosphere, trioxygen molecules can absorb harmful ultraviolet radiation from the sun, preventing it from reaching Earth's surface, where it can harm organisms and raise surface temperatures. In the lower atmosphere, ozone acts as a greenhouse gas, trapping thermal radiation.

Why the Antarctic climate enabled British scientists to discover the ozone hole

In the Antarctic stratosphere, polar conditions facilitate the formation of polar stratospheric clouds, which allow chlorine compounds from chlorofluorocarbons to accumulate. In 1985, British Antarctic Survey scientists detected massive springtime losses over Antarctica, as accumulated compounds destroyed significant amounts of ozone once sunlight returned.

How a black market for banned refrigerants still threatens ozone recovery and climate progress

Despite the Montreal Protocol's success, illegal trade in chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons persists. Driven by high profits and weak enforcement, smugglers supply banned refrigerants, causing significant ozone depletion and greenhouse gas emissions equivalent to billions of tons of carbon dioxide.

Why Earth would become a more deadly environment without the ozone layer

The ozone layer blocks almost all of the sun's harmful, including dangerous UVC rays that can damage cells by breaking chemical bonds. Without it, rates of skin cancer, crop failures, oceanic die-offs, and widespread ecosystem collapse would increase significantly, making Earth largely uninhabitable.

The ozone layer is on track to recover to pre-1980 levels by mid-century

Thanks to the Montreal Protocol, the ozone layer is steadily recovering and, according to a 2022 assessment, is expected to return to 1980 levels by 2040 globally, 2045 over the Arctic, and 2066 over Antarctica.

How a skin cancerous growth shifted an initially skeptical President Reagan on the ozone crisis

While a 1985 Nature study revealing the Antarctic ozone hole jolted public concern, Reagan's administration was more focused on the Cold War than on environmental policy. His health scare and the market potential for developing alternatives to chlorofluorocarbons helped turn the tide, leading to the Montreal Protocol's unanimous ratification by a bipartisan Senate in 1988.

Why bacterial bioremediation may help counter the negative effects of past chemical solutions

Molecules such as DDT, a synthetic insecticide, and PFAS—"forever" chemicals used to make products resistant to heat, water, and grease—have historically been used across various industries but are now known to be harmful. Microbes that can convert some of these substances into nontoxic products, such as water and carbon dioxide, have already been identified, with ongoing research to find others.

Carbon dioxide acts as a 'control knob' for Earth's climate

Although Earth's ice ages were primarily triggered by slow changes in the planet's orbit—known as Milankovitch cycles—these changes do not explain the extreme temperature swings during glacial periods. Carbon dioxide acts as a feedback mechanism, intensifying both cooling during ice ages and warming during their ends by reinforcing the initial changes sparked by orbital shifts.

How artificial photosynthesis can help make plastics and fuels using sunlight

These systems link a molecular light absorber to a catalyst that can synthesize fuels—such as ethanol—and ethylene, a precursor to plastics, in a carbon-neutral manner. Because these byproducts have greater energy concentrations than the carbohydrates produced by photosynthetic organisms, research is ongoing to engineer the necessary catalysts.

Broken or neglected air conditioners are risky for respiratory health

A well-maintained air conditioner can typically keep out unwanted pathogens, but units that are dusty or water-logged can foster germs and cause harm. AC units also remove moisture from the air, potentially causing mucus membranes to dry out and become vulnerable to infection.

How climate change threatens coral reefs, including via warming and acidification

Increasing ocean temperatures disrupt the symbiotic relationship of corals and algae, causing the former to bleach and weaken, and strengthen storms that can destroy reef structures. Higher greenhouse gas emissions increase dissolved carbon dioxide levels in ocean water, triggering a series of reactions that consume carbonate, a key ingredient in coral reef construction.

The weakest form of light that is dangerous to humans is ultraviolet

Unlike radio waves, microwave, infrared, and visible light, UV light can produce chemical changes, such as curing adhesives and resins, causing substances to fluoresce, and destroying the genetic material of microorganisms. This makes UV light useful for sterilization, forensics, and quickly drying nail polish.

Demystifying sunscreen

Sunscreen is helpful all year round. Experts argue a minimum level of protection is SPF 30. There are two kinds of sunscreen: mineral (a physical barrier) and chemical (absorbs UV light). No new sunscreen ingredients have been approved in the US in decades, so foreign products are common.

Odor blockers use nonpolar oils to trap smelly polar molecules

In the case of feces, gut bacteria produce compounds such as skatole and hydrogen sulfide, which the brain registers as unpleasant. Because oils do not dissolve in water, they can be used to create a layer on the surface that prevents smelly compounds underwater from escaping into the air.

Chemtrails are formed from condensing water vapor and soot from jet fuel

Conspiracy theories about the phenomenon—also known as contrails—began circulating in the 1990s, but have gained significant traction on social media platforms. Chemtrails are more common in high-humidity conditions, where they persist and form cirrus clouds.

Why Earth's atmosphere constantly loses the universe's lightest elements to space

The masses of hydrogen and helium are too small for these gases to be held by Earth's gravitational force, particularly when these atoms are given energy from collisions with high-speed particles from the sun. Although the planet loses a meter-wide balloon's worth of hydrogen every second, it will still take billions of years to exhaust the planet of this element.

How cosmic rays and pointed ice shards help generate lightning in clouds

Although clouds generate electric fields as electrons are transferred when currents move past one another—not unlike building up static electricity by rubbing socks against carpet—these fields have been measured to be a tenth of the strength needed to make electricity strong enough to travel through air. However, pointed crystals are estimated to boost fields by factors greater than 10, and particles from outer space may help initiate cascades of displaced electrons.

Climate models use complex equations and supercomputers to predict future climate

The equations apply the laws of thermodynamics, fluid motion, and radiative transfer to a 3D grid along Earth's surface. After solving them for each cell in the grid over a time interval, the results carry over to neighboring cells, and the process repeats into the future.

Copper is responsible for turning blonde hair green in swimming pools

Pools use copper sulfate to control algae, which can bind to hair either damaged by the sun or recently bleached. Chlorine, which is often considered to be the culprit, weakens the hair structure to exacerbate the green coloration reaction, rather than causing it.

A composite of telescope images of the sun, which each reveal unique solar features

While traditional cameras can reveal sunspots—cooler regions on the sun's surface—in visible light, x-ray detectors can highlight explosions of high-energy plasma and magnetic fields known as coronal mass ejections. Hydrogen-alpha filters can reveal clouds and filaments of material suspended in magnetic fields above the sun's surface.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Why water is the universal solvent, despite not being good at dissolving many substances

Because oxygen attracts electrons much more strongly than hydrogen does in H₂O, the molecule is polar, with a negative charge at the oxygen atom and positive charges at the hydrogen atoms. These charged regions can attract and pull apart charged portions of other polar molecules, such as washable inks, but are unable to dissolve nonpolar materials, such as glass and asphalt.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Shooting stars, or meteors, are fragments of asteroids and comets that burn up as they enter Earth's atmosphere, creating streaks in the sky called meteor showers.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

US intelligence allegedly pursued more than 600 schemes to assassinate Cuban revolutionary Fidel Castro.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

One disco producer saw 'Star Wars' four times on its opening weekend and was so inspired that he recorded the album 'Star Wars and Other Intergalactic Funk,' which produced a chart-topping single.

Mid-century modern graphic designers, known for their bright colors and bold lines in advertising, also found success with children's books.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions