New research studying the effects of air pollution has discovered that thanks to these floating pollutants, eastern China has received reduced rainfall over the past 50 years. It has decreased by 23 percent the number of days of light rain in the eastern half of the country.
Atmospheric scientist Yun Qian at the Department of Energy's Pacific Northwest National Laboratory led the research.
AdvertisementThe results suggest that bad air quality might be affecting the country's ability to raise crops as well as contributing to health and environmental problems.
The study links for the first time high levels of pollutants in the air with conditions that prevent the light kind of rainfall critical for agriculture.
"People have long wondered if there was a connection, but this is the first time we've observed it from long-term data," said Qian.
"Besides the health effects, acid rain and other problems that pollution creates, this work suggests that reducing air pollution might help ease the drought in north China," he added.
Over the last 50 years, the southern part of eastern China has seen increased amounts of total rainfall per year.
The northern half has seen less rain and more droughts. But light rainfall that sustains crops has decreased everywhere.
A group of climate researchers from the US, China and Sweden wanted to know why light rain patterns haven't followed the same precipitation patterns as total rainfall.
Air pollution contains tiny, unseen particles of gas, water and bits of matter called aerosols. erosols - both natural and human-caused (anthropogenic) - do contribute to rainfall patterns, but the researchers needed to determine if pollution was to blame for China's loss of rain and how.
To find out, the team charted trends in rainfall from 1956 to 2005 in eastern China, which has 162 weather stations with complete data collected over the entire 50 years.
From this data, the team determined that both the north and south regions of eastern China had fewer days of light rain - those getting 10 millimeters per day or less - at the end of the 50 year time span.
The south lost more days - 8.1 days per decade - than the north did, at 6.9 days per decade. owever, the drought-rattled north lost a greater percentage of its rainy days, about 25 percent compared to the south's 21 percent.
"No matter how we define light rain, we can see a very significant decrease of light rain over almost every station," said Qian.