Dirty old birds shed light on key global warming particle

This image provided by Carl Fuldner and Shane DuBay show Field Sparrows, from 1906, top, and from 1996, bottom, that are in the The Field Museum collection. Scientists say more than 1,000 dirty stuffed old birds from Midwestern museums are helping them better understand a key global warming particle. Researchers found birds from about 100 years ago showed lots more black carbon, often called soot, than just 20 or 30 years later, and more than scientists had thought. That’s important because black carbon is a potent heat-trapping molecule. (Carl Fuldner and Shane DuBay via AP)

WASHINGTON (AP) — Scientists say more than 1,000 stuffed birds from Midwestern museums are helping them better understand a key global warming particle.

Researchers reported Monday that they found more soot on birds in museums in Chicago, Detroit and Pittsburgh than they expected. They also found more soot on the birds from the 1900s and 1910s than they did decades later, when people turned away from using coal to heat their homes.

Soot, also called back carbon, is important to climate change because it helps trap heat. But it has been difficult for scientists to study how levels of it have changed over time because it doesn’t last long in the atmosphere.

The study is in Monday’s Proceedings of the National Academy of Sciences.