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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

47 mins ago - World

Brazil senators vote to recommend criminal charges for Bolsonaro

Brazilian senators vote on probe into President Bolsonaro's handling of pandemic. Photo: Gustavo Minas/Bloomberg via Getty Images

A Brazilian Senate committee Tuesday voted to approve a report recommending President Jair Bolsonaro be charged with a raft of criminal indictments, including crimes against humanity over his response to the COVID-19 pandemic, per AP.

Why it matters: Bolsonaro has become the face of a right-wing approach to the pandemic that includes repudiating vaccines and masks and resisting lockdowns and other mitigation measures. The Senate report holds him personally responsible for half of the country's 600,000 deaths.

Former Georgetown tennis coach pleads guilty to accepting admissions bribes

Gordon Ernst (left) former head tennis coach at Georgetown, outside a courthouse in Boston in 2019. Photo: Jessica Rinaldi/The Boston Globe via Getty Images

A former Georgetown University head tennis coach has pleaded guilty Tuesday to bribery charges related to facilitating the admission of prospective applicants.

Why it matters: Gordon Ernst solicited and accepted bribes from William Singer, ringleader of the cheating scheme uncovered by Operation Varsity Blues, and families in exchange for helping prospective applicants get into Georgetown as student athletes, according to the Justice Department.

4 hours ago - Health

CDC says some immunocompromised people can get fourth COVID shot

Photo: Noriko Hayashi/Bloomberg via Getty Images

The Centers for Disease Control and Prevention said in updated guidelines Tuesday that some immunocompromised people who have received either Pfizer or Moderna's COVID-19 vaccines will be able to get a fourth shot.

Details: People over 18 who are "moderately to severely immunocompromised" and have received three doses of an mRNA vaccine may get a fourth shot (of either the Pfizer, Moderna, or Johnson & Johnson vaccines) at least six months after getting their third Pfizer or Moderna dose, per the CDC.

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