climate model

In winter, one part of town gets three times as much snow as the neighborhood next door. One year is a scorcher, the next is a cold snap. That's the whims of weather. But over decades, a different, slow shift emerges: winters, on average, get milder. Telling the two apart is the central challenge for climate scientists.

Meteorologists have grown used to trusting neural networks: the GraphCast model predicts Earth's weather days ahead by drawing on global snapshots of the atmosphere. But this 'brain' can be transplanted to another planet — where the air is thin and the Sun warms differently.

For decades, global atmospheric models resembled artists forced to paint planetary storms with coarse brushstrokes: a resolution of 25–100 km forced them to 'guess' convection through approximate schemes, introducing systematic errors in rainfall and climate forecasts.

A translator in a conference hall tries to convey the speaker's words, but the hall is noisy: someone coughs, chairs creak, and the street outside is loud. If the speaker lowers their voice, the translator still keeps translating, but their voice drowns in the noise.

Every year, the food we eat costs humanity tens of millions of years of life due to unhealthy diets. At the same time, a third of all greenhouse gases warming the planet are produced along the journey from farm to plate. It seems obvious: switch to healthier eating, and we'll save the climate and improve our health. But new research shows these two goals don't always go hand in hand.

Deep underground, in the thickness of granite, detectors catch rare visitors from space — muons. These particles are born high in the atmosphere when cosmic rays slam into air nuclei. They make it to the underground lab thanks to their enormous speed, close to the speed of light.

In the Atlantic, a giant invisible conveyor operates: warm surface waters flow north, cool, sink, and return south. This circulation, AMOC, carries heat, making Europe noticeably milder than Canada at the same latitudes. But the conveyor isn't eternal: if diluted by fresh water from melting Greenland ice, the engine stalls.

For 800,000 years, ice ages have occurred every 100,000 years. The rhythm matches the elongation of Earth's orbit. But the orbit changes the flow of solar heat so subtly — as if the conductor barely moved the baton, yet the orchestra thundered. It remained a mystery how this weak signal controls the ice sheets.

A radiation sensor in the city is like a street musician: it has to hit the right notes even when fingers go numb from cold or the instrument is baked by the sun. Usually, such devices are kept in greenhouse conditions, with heating or cooling, otherwise the energy scale (which distinguishes harmless potassium in concrete from dangerous cesium) starts to lie.

The weather on the next street can differ from yours: cooler by the river, hotter over asphalt, windier between buildings. A regular forecast misses this: its grid cell is the size of a city, not a backyard.

A cell is a city where tiny motors work nonstop. They carry cargo, move cilia, and make muscles contract. All this work generates heat, just like a car engine warms up. But measuring the heat from a single motor a few nanometers in size is no easy task. Stochastic modeling helps us peek into this world.

A planet's climate is like an old spring mattress: press down on one edge, the springs compress; let go, they rebound and put everything back. Earth has three such springs, working as a team. Carbon dioxide weathers out of rocks, clouds reflect sunlight, and ice caps bounce heat back into space. Together, they keep the planet from boiling or freezing.

When an X-ray burst erupts on a neutron star, its atmosphere heats up to millions of degrees. The light we catch with telescopes passes through this dense layer of gas, and gets dramatically altered along the way. The spectrum no longer looks like that of an ideal radiator: some colors get amplified, others dim.

Scientists built a model of Earth with all living organisms removed — from bacteria to trees. Over billions of years, this 'empty house' didn't turn into an icy desert. Volcanoes, like a furnace, release carbon dioxide, and rock weathering, like a thermostat, absorbs it.

Glaciers don't just darken from soot. Their surfaces host tiny algae that, as temperatures rise, bloom and turn the ice dark. Dark ice absorbs more sunlight, melts faster, and further warms the planet. It's like how a black t-shirt in the sun gets hotter than a white one. The second player in overheating is forests.

For a long time, the climate of ancient Mars remained a mystery: the beds of dried-up rivers spoke of water, but models couldn't explain how it got there — after all, 4 billion years ago the Sun shone 30% dimmer. New research shows that the planet swayed, as if on a swing, between long glaciations and short wet epochs.

Rain doesn't fall just any old way. If you take records from nearly fifty thousand rain gauges scattered across the globe and compare how much water falls on a rainy day in different parts of the planet, you'll spot a surprising pattern.

In 1992, Hurricane Andrew tore through Florida, leaving insurers with $$15.5 billion in losses. Many companies went bankrupt, and the market devised a way to shift disaster risk onto investors: catastrophe bonds. These securities pay generous coupons as long as a specified disaster does not occur, such as a hurricane of a certain strength or an earthquake in a particular region.

Climate forecasting is like a complex recipe: one wrong pinch and the whole dish is ruined. So it is with clouds — small but decisive. Climate models divide the sky into 50–100 km cells and don't see individual clouds. It's like throwing pepper by the handful when the recipe calls for a pinch.

An orchestra of two musicians plays from the same score, but each hears only their own line. The atmosphere and ocean in a climate model resemble such a duet: they exchange heat and moisture every few hours, yet until recently their neural network counterparts could not keep a common rhythm.

For 36 days, tropical cyclone Freddy raged over the Indian Ocean, the longest-lived cyclone on record. Meteorologists tracked it from satellites, aircraft, and ground stations. But one detail eluded all instruments: the precise air density deep within the vortex. And that density determines where the cyclone will turn tomorrow.

A translator at a high-stakes negotiation doesn't just render words quickly; they make sure the meaning doesn't get lost. CAMulator does the same: it takes the complex climate model CAM6 and translates it into the language of a neural network that runs hundreds of times faster, without losing the physical essence.

Two dancers stand facing each other but cannot see each other's faces. One is the atmosphere, fast and noisy, forgetting its moves after just a couple of weeks. The other is the ocean, slow and heavy, remembering every touch for months. For the dance to work, they need to learn to lead each other while only looking at their partner's hands.

A translator at an important negotiation starts by simply repeating words, but gradually begins to anticipate what the counterpart will say. The new weather model works similarly: physics provides the framework, and machine learning learns from errors and fills in the gaps.

Climate is like an orchestra without a conductor: each musician hears the others with a delay, and the score changes mid-concert. The ocean, atmosphere, ice, and land continuously exchange energy, and the slightest hiccup in one instrument can escalate into a shift of the entire melody.

Water remembers. Every current, every eddy, every degree of temperature in the ocean's depths does not vanish without a trace; it leaves a mark that can be read. But until recently, that mark was read only by bulky physical models that spent weeks on supercomputers and still got the details wrong.

Over warm ocean waters, air rises, spins, and turns into a giant vortex that carries winds faster than a race car. For such a vortex to form, several conditions must align: rotation, heat, moisture, and calm winds aloft. Previously, meteorologists combined these conditions into complex indices, like a kitchen recipe with a dozen ingredients.

In February 2022, the eastern coast of Australia was hit by rains that lasted several days in a row. Water inundated towns in Queensland and New South Wales, insurers paid out 3.35 billion dollars, and the flood became the costliest in the country's history.

On a meadow in Laqueuille, perched at 1040 meters in the Massif Central, grass doesn't grow at the whim of weather but follows a schedule set by the ocean thousands of kilometers away. From 1959 to 2015, the PaSim pasture model, fed with hourly weather data from the SAFRAN archive, simulated grass growth while excluding pests and farmer interventions. What remained was a pure climatic signal.

Picture an orchestra where each instrument plays at its own tempo: violins speed up, woodwinds slow down, and percussion keeps losing the beat. That's roughly what Earth's climate looks like, with the ocean, the Sun, volcanoes, and human activity pulling temperature in different directions.

In the mountains, an echo repeats any shout, and you can't immediately tell who shouted: a person or the wind. That's roughly how climate scientists work when they try to understand why an unusual heat wave or drought happened. They look for a human fingerprint in a weather disaster, but nature has its own voices that can sound similar.

An interpreter at a negotiation hears not only the volume of the voice but also the shift in topic. Climatologists have long listened only to volume: the average temperature. If it rises, the planet is warming. But behind the average hide events that matter more than the trend: heat waves, cold snaps, sudden changes.

A meteorologist looks at a map where clouds gather in flocks, like birds before a storm. Each spot on the radar could be a future downpour or just noise. Earth system forecasting is like trying to assemble a puzzle with thousands of pieces that keep changing shape.

Warm air rises from a radiator, and the room seems to heat evenly. But if you put your hand against the wall by the window, it feels cooler than by the door.

The ocean off the coast of Peru warms and cools, and with it the whole planet runs a fever: rains flood deserts, and tropical forests dry out. This is El Niño, the most noticeable climate oscillation after the changing seasons. For half a century, it has been described by a single number: the water temperature in a small square of ocean.

Every summer, a giant atmospheric engine unfolds over India: moist ocean winds bring the rains that sustain crops and the lives of two billion people. But this engine sputters, and forecasting it a season ahead remains elusive. Models give only rough answers, and a monsoon forecast error can cost millions of tons of food.

A gunner adjusts the eyepiece of a telescope: one more click, and the blurry blob becomes a crisp image. Climate scientists at the Institute of Atmospheric Physics, Chinese Academy of Sciences, made a similar adjustment to their model ICM.

Soil breathes. The top layer of the earth takes in moisture after rain, then releases it into the air, much like lungs inhale and exhale. This inhalation and exhalation happens everywhere on the planet, but its rhythm is not uniform: in some places it is fast and steady, in others irregular and deep.

Two people are talking at once, and by the loudness of their voices you can't tell who is answering whom. That's how climatologists have for decades searched for a link between warm water off the coast of Peru and droughts in Australia: they compared how synchronously ocean temperature and rainfall change in different parts of the planet.

A farmer in Iowa looks at the calendar: plant now or wait? In a month, a heat wave might strike, or rain might set in. Forecasters throw up their hands: the two-week forecast still holds, the seasonal one is out of reach, and in between lies a gap. The atmosphere changes too quickly to remember yesterday, and the ocean is too slow to come to the rescue.