Sulfur's climate role is complicated. In the air, it can form tiny particles called aerosols, creating new ones or building up old ones. Aerosol particles help form cloud drops, potentially changing rainfall amounts as well as affecting the acidity of the raindrops. Both clouds and the aerosols themselves reflect sunlight, reducing the amount of energy absorbed by the planet.
To determine how much sulfur has been emitted between the approximate beginning of the Industrial Age, 1850, and 2005, Smith and colleagues analyzed data about sulfur-emitting activities such as coal burning, copper smelting, or the use of petroleum. The data came from more than 140 countries and went back as far as the 1800s, when publications even at that time tallied how much coal and copper were produced.
The team collected the datasets, evaluated the quality of the records and plotted the data over time, breaking them down by region, source -- such as coal or oil burning -- and economic use such as heating or cooking, power production, and others.
The team estimated emissions data both by calculating sulfur release based on how much was contained in sources as well as from actual data on emissions collected from modern power plants. In the United States, government agencies such as the Environmental Protection Agency and the Department of Energy collect such data.
The factors that determine total emissions are the amount of fuel consumed, its sulfur content, and any pollution controls employed. The team found that manmade sources of sulfur emissions eclipsed natural sources by 1870, two decades after the start date of this analysis. By the year 2000, however, refineries were removing half the sulfur from crude oil, reducing emissions, the researchers estimated.
Since 1980, the fraction of sulfur coming from
|Contact: Mary Beckman|
DOE/Pacific Northwest National Laboratory