How Are Birds Helping Scientists Rewrite Pollution History?

Monitoring pollution is important because it informs us of the main problems and current threats to the environment from our actions. It’s also useful in the long term, however, because it gives us an understanding of how pollutant levels are changing over time.

The problem? Pollution monitoring wasn’t always as effective as it is now. As a result, there’s sometimes a lack of accurate information for pollution levels in the past. However, that information may be available from an unlikely source. Read on to see how birds can help scientists study pollution in the past.

Studying black carbon

In the US, environmental scientists are studying the effects of black carbon. The substance is formed when fossil fuels and biomass are incompletely combusted, and is emitted as soot. It’s one of the big problems for the mining industry, which can be made more sustainable in a variety of ways.

Black carbon is known to have a disastrous impact on human health, causing hundreds of thousands – and even millions – of deaths each year. But researchers are also interested in how it contributes to climate change. When it’s held in the air, black carbon absorbs light from the sun and causes atmospheric temperature to rise. Then when it reaches the ground it’s thought the substance causes more snow and ice to melt, meaning increased levels of ice loss in the Arctic.

The role birds play

One challenge for studying the effects of carbon on things like health and ice loss is the lack of accurate information from past decades. However, a new study has analysed over a thousand birds from natural history museums. By measuring levels photographing birds and measuring how much light was reflected off them, they could calculate the levels of black carbon trapped in their feathers.

This has allowed them to create more accurate records of black carbon levels and how they have changed over time. They found a peak in the first ten years of the 1900s, followed by a slump during the US great depression and subsequent boom through World War II in the 1940s. From the 50s onwards, levels seem to have fallen as gas rose to prominence as a heating fuel.

Improving into the future

As well as providing a more accurate picture of the past, the new findings could make for more accurate modelling for future events. “The big finding and implication of our study is that we are recovering relative concentrations of atmospheric black carbon that are higher than previously estimated from other methods," said University of California’s Shane DuBay. "It helps constrain and inform how we understand the relative role of black carbon in past climate and by understanding that we can more accurately model future climate scenarios.”