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Earth’s climate is chaotic. The winners of the 2021 Nobel Prize in physics found patterns in the noise.

Klaus Hasselmann, Syukuro Manabe, and Giorgio Parisi shaped climate change models and our understanding of the future.

Syukuro Manabe of Princeton University, Klaus Hasselmann of the Max Planck Institute for Meteorology in Hamburg, Germany, and Giorgio Parisi of the Sapienza University of Rome (seen projected) were awarded the Nobel Prize in physics.
Jonathan Nackstrand/AFP via Getty Images

Three scientists who began to cut through the chaos of the global climate, laying the foundation for forecasts about the future of the planet, were awarded the 2021 Nobel Prize in physics on Tuesday.

Half of the $1.1 million prize was awarded to Giorgio Parisi, 73, of Sapienza University in Italy, for his work quantifying randomness and connecting the movement of atoms to the planet as a whole. The other half was split evenly between Syukuro Manabe, 90, of Princeton University, and Klaus Hasselmann, 89, of the Max Planck Institute for Meteorology in Germany. Manabe and Hasselmann developed models that could make reliable forecasts despite the inherent volatility of the planet’s climate system.

“I am so surprised,” Manabe told the Nobel Prize website. “Nobody has received the physics prize for my kind of work, and I really appreciate the Swedish Academy of Sciences [for choosing] this field, climate topics and climate change.”

The big picture of climate change is straightforward enough: Heat-trapping gases in the atmosphere are turning Earth into a metaphorical greenhouse, making the planet warm up.

But exactly how that warming will occur — across the planet’s oceans, ice caps, mountains, forests, and cities, fueled by everything from methane leaks to carbon dioxide to hydrofluorocarbons — is extraordinarily messy.

“We are awash in complexity at every scale we observe, and [as] scientists, we ask: How much detail is required to explain the observations?” John Wettlaufer, a physicist at Yale University, said at the press conference announcing the prize. “Must we track every water molecule to explain the ocean?”

The physics laureates found ways to account for the roiling randomness present in everything from materials to the motion of the atmosphere, and still make useful predictions.

The Nobel Prize committees have recognized the global challenge of climate change before. The 2007 Nobel Peace Prize was awarded to former US Vice President Al Gore and the Intergovernmental Panel on Climate Change, a global group of leading climate scientists convened by the United Nations. The 2018 economics prize was shared by William Nordhaus, who developed a model that integrated physical climate models and economics, quantifying the social impacts of warming.

Now climate modeling is getting a turn in the spotlight. Figuring out exactly how the planet will warm up is urgent: It will shape where crops can grow, where people can live, and what the rising onslaught of disasters will cost. These scientists, and the stark future they helped to illuminate, are still shaping humanity’s efforts to avert a global catastrophe.

How scientists found patterns in chaos

Climate science has rapidly advanced in recent years, but the foundations were laid hundreds of years ago and predate the Nobel Prizes, which were first awarded in 1901.

In the 1820s, French scientist Joseph Fourier theorized that the Earth must have some way of retaining heat and that the atmosphere may play some role. In 1850, American scientist Eunice Newton Foote put thermometers in glass tubes and experimented with placing them in sunlight. Inside the tubes, Foote compared dry air, moist air, and carbon dioxide, and found that the tube containing CO2 warmed up more than the others and stayed hotter longer.

“An atmosphere of that gas would give to our earth a high temperature,” she wrote in a paper presenting her findings.

In 1859, Irish scientist John Tyndall began quantifying how much heat different gases in the atmosphere absorb. “As a dam built across a river causes a local deepening of the stream, so our atmosphere, thrown as a barrier across the terrestrial rays, produces a local heightening of the temperature at the Earth’s surface,” Tyndall wrote.

And in 1896, Swedish scientist Svante Arrhenius calculated by how much carbon dioxide warms the planet and in his later work theorized that more carbon dioxide in the atmosphere would cause the planet to heat up.

But figuring out how these larger trends play out on smaller, more tangible scales proved complicated. How much a given region would warm up with more greenhouse gas emissions hinges on local conditions like tree cover, air pollution, wind patterns, and rainfall in addition to how much heat the atmosphere can trap.

As a meteorologist for the US government and at Princeton in the 1960s, Syukuro Manabe connected energy absorbed by the atmosphere to the movement of air vertically over the Earth, a critical parameter for simulating the climate.

Syukuro Manabe shared the 2021 Nobel prize in physics for his work in developing climate models.
Syukuro Manabe showed how the atmosphere traps heat, accounting for the movement of air and water. It’s a vital parameter in climate models.
Royal Swedish Academy of Sciences

At the Max Planck Institute for Meteorology in the 1980s, Klaus Hasselmann worked to connect rambunctious, short-term weather patterns with long-term shifts in the climate. He found that even noisy weather data could yield insight into broader patterns, and even allow scientists to trace human influence on the climate. These findings planted some of the earliest seeds of climate attribution science, which scientists now use to quantify just how much humans have worsened a given heat wave or torrential downpour.

Giorgio Parisi’s work wasn’t inherently linked to climate systems, but his research in the 1980s proved that the seemingly random movements of particles could be quantified into patterns and predictions. This insight helped climate scientists build simulations up from individual gas molecules.

In the decades since this early work, climate models have grown more sophisticated, and computing power has started to catch up. It’s given researchers a clearer vision of the future should greenhouse gases continue surging in the sky.

But the greatest uncertainty in climate forecasts remains what humanity will do — whether countries, corporations, and individuals will choose to cut their harmful emissions rapidly and drastically. And that remains, as scientists say, an area of active research.

“Most urgently needed is action against climate change,” Hasselmann told the website of the Nobel Prize. “There are many things we can do to prevent climate change, and this is the whole question of whether people will realize that something which will happen in 20 or 30 years is something you have to respond to now.”

It’s up to us to solve the problem that Hasselman, Manabe, and Parisi helped the world understand.

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