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Field sparrows from 1906 (top) and 1996 (bottom). The top bird is covered in soot. Photo: PNAS

Comparing the feathers of songbird specimens collected in the Rust Belt over 135 years, researchers at the University of Chicago report there was more soot in the air during the early 20th century than originally estimated.

Why it matters: Soot or black carbon from burning coal contributes to climate change but is difficult to study because it falls out of the atmosphere after a few days or weeks. Researchers want to be able to accurately assess soot's role in past warming in the past in order to improve predictions about future contributions.

How they did it: Carl Fuldner and Shane DuBay measured how much light was reflected in the feathers of 1347 birds representing five species collected between 1880 and 2015. The birds molt each year so the soot in their feathers is an accurate proxy of that in the air during the year they are collected.

What they saw: The birds' feathers were covered in the most soot between 1880 and 1929. During the Great Depression when less coal was burned, the feathers were cleaner but then became dirty again during World War II. After the war ended in 1945, the amount of soot on the feathers declined, a trend that continued as air pollution legislation was enacted in the middle of the century.

What it means: The AP's Seth Bornstein writes some scientists think black carbon emissions should be a focus of fighting climate change while others "say the impacts of the study on projections for future warming would likely be modest — at best — in part because black carbon stays in the atmosphere for such a short time."

Go deeper

Dan Primack, author of Pro Rata
32 mins ago - Economy & Business

Scoop: Red Sox strike out on deal to go public

Illustration: Sarah Grillo/Axios

The parent company of the Boston Red Sox and Liverpool F.C. has ended talks to sell a minority ownership stake to RedBall Acquisition, a SPAC formed by longtime baseball executive Billy Beane and investor Gerry Cardinale, Axios has learned from multiple sources. An alternative investment, structured more like private equity, remains possible.

Why it matters: Red Sox fans won't be able to buy stock in the team any time soon.

Trump political team disavows "Patriot Party" groups

Marine One carries President Trump away from the White House on Inauguration Day. Photo: Patrick Smith/Getty Images

Donald Trump's still-active presidential campaign committee officially disavowed political groups affiliated with the nascent "Patriot Party" on Monday.

Why it matters: Trump briefly floated the possibility of creating a new political party to compete with the GOP — with him at the helm. But others have formed their own "Patriot Party" entities during the past week, and Trump's team wants to make clear it has nothing to do with them.

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