Nobel Prize in Physics awarded for climate and complex models

The Royal Swedish Academy of Sciences awarded the 2021 Nobel Prize in Physics was awarded to two scientists studying climate, and one studying complex systems.

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As severe weather across the globe is becoming more frequent, it’s fitting that The Royal Swedish Academy of Sciences awarded the 2021 Nobel Prize in Physics was awarded to two scientists studying climate, and one studying complex systems.

The work of Klaus Hasselmann and Syukuro Manabe paved the way for predicting and modeling climate change and the undeniable role of human emissions. Giorgio Parisi devised a way to understand complex systems that is applicable to mathematics, biology, neuroscience and machine learning.

Manabe and Hasselmann will split half of the ~1.1 million dollar prize, and Parisi will receive the other half.

Though Manabe and Hasselmann’s awarded work was completed decades ago, these Nobel laureates’ research is now the foundation for myriad works, which is in no small part why they were awarded this year’s prize. The laureate’s work also points a clear finger toward carbon dioxide emissions’ role in climate change, which is well known now.

“The knowledge that we have today really rests on the shoulders of these giants,” said Emile-Geay, associate professor of earth sciences at USC Dornsife. “It’s important to kind of honor that memory and realize that we’re not starting from scratch when it comes to something like climate change.”

Hasselmann, a professor at the Max Planck Institute for Meteorology in Hamburg, Germany, conducted research focused on connecting weather and climate to show that they affect each other. With that foundation, he was able to show the undeniable human impact on climate.

Hasselmann created a model that links the unpredictable nature of weather with the long-term trends of climate. The ingenuity is that his model is stochastic, or includes randomnesses.

He was able to demonstrate that rapid weather changes can affect the ocean trends. Though not the same, changes in climate can also result in severe weather events such as fires or droughts.

“There have always been fires and droughts and hurricanes before humanity ever had the ability to tinker with the weather—tinker with the climate,” Emile-Geay said. “The big heatwave that scorched the Pacific Northwest over the summer would have been incredibly unlikely in a world where we hadn’t been burning as much fossil fuels.”

Hasselmann, in an interview with Chief Scientific Officer of Nobel Prize Outreach Adam Smith, said, “to distinguish between the long-term climate change and the shorter term of a few months or years that you see on weather changes is sometimes difficult to decide.”

Manabe’s research points to carbon dioxide concentration as the chief contributor to climate change. Manabe, a senior meteorologist at Princeton University, created the first model of the earth’s atmosphere that accounted for the greenhouse effect and air movement.

The greenhouse effect refers to the earth atmosphere reflecting radiation from the earth’s surface back toward the earth. The air movements modeled are the convection currents that carry moisture up, which precipitate down.

Burning fossil fuels for energy production or transportation, wastewater treatment and agriculture are significant sources of CO2, which can last in the atmosphere for centuries, according to Emile-Geay. “That’s why it’s so critical to act as soon as we can,” he said.

“Climate change is an issue that affects everyone that we see more and more in the news when we think about wildfires, droughts, particularly in California or extreme rainfall, hurricanes on the East Coast,” said Julien Emile-Geay.

Manabe found that the atmosphere’s concentration of oxygen and nitrogen had negligible effect on surface temperature, and the strength of the sun’s heat did not align with collected data. He found that carbon dioxide was responsible for hotter temperatures on the earth’s surface.

He completed his analysis on 1960s era computers, which took weeks. Students in Emile-Geay’s GEOL 351 class run similar models on laptops in seconds.

Less related to climate modeling, Parisi, a professor at Sapienza University of Rome in Italy, discovered hidden patterns in spin glass. The insights from spin glass can be used when answering other problems, such as why there are periodic ice ages or how patterns emerge in flocks of birds.

Contrary to its name, spin glass does not rotate and is not glass, but instead a metal.

Spin glass refers to a material with a mix of copper and iron atoms, with each iron atom behaving like a tiny magnet. The spin refers to the direction of each of the tiny magnets, and glass refers to the chaotic orientations of the magnets, which resembles the atomic structure of glass.

Parisi noticed statistical patterns in the spin glass and was able to describe them mathematically.

“[He] tamed this complicated landscape by building a deep physical and mathematical model, which was so broad that it has impacted a vast range of fields far beyond spin glasses, from how granular materials pack, to neuroscience, to how we compute to random lasers and to emergent phenomenon far beyond what he envisioned in the 1970s when he started this work,” said the Nobel committee member John Wettlaufer, a professor of earth and planetary sciences at Yale University in the U.S. to The Guardian.

In a phone call, Parisi to said to Smith, “there are very, very, simple problems that are very hard to understand.”