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."

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Trump says he intends to give RNC speech on White House lawn

President Trump speaking to reporters on South Lawn in July. Photo: Jabin Botsford/The Washington Post via Getty Images

President Trump told the New York Post on Thursday that he plans to deliver his Republican National Convention speech from the White House lawn, despite bipartisan criticism of the optics and legality of the location.

Why it matters: Previous presidents avoided blurring staged campaign-style events — like party conventions — with official business of governing on the White House premises, per Politico.

Fauci's guidance on pre-vaccine coronavirus treatments

Illustration: Aïda Amer/Axios

Antibody drugs and various medicine cocktails against the coronavirus are progressing and may provide some relief before vaccines.

The big picture: Everyone wants to know how and when they can return to "normal" life, as vaccines are not expected to be ready for most Americans for at least a year. Two therapies are known to be helpful, and more could be announced by late September, NIAID Director Anthony Fauci tells Axios.