Yellow Dust

In the fifth year of Di Xin, it rained dust at Bo.

–The Bamboo Annals

In the past decade, Americans living east of the Mississippi have become accustomed to occasional skyscapes that were previously confined to the West. At times, the Sun’s disk can almost be viewed safely with the naked eye during the day, as if at rise or set. Air quality alerts might stretch for days. Showers can bring murky water to the ground. These symptoms come from wildfires thousands of miles away in Canada or America’s Pacific coast.

It’s an unsettling reality of the 21st century. The trigger could be half a world away, but the planet’s climatic systems can transport smoke tremendous distances.

Though modern practice has exacerbated these types of situations, both in severity and frequency, they are not limited to contemporary times, and they can occur naturally. Wildfires, of course, existed before humans could over-log and alter the climate. Natural fires are often healthy for ecosystems, though they tend to happen on smaller scales than today’s conflagrations.

Burning biomass isn’t the only phenomenon that can produce oddly obscured skies.

People living in eastern Asia have experienced similar atmospheres for thousands of years, thanks to a happening they call yellow dust.

Also called Asian dust, yellow sand, yellow wind, or the Japanese term kosa, yellow dust plagues the skies of China, the Koreas, Japan, and parts of eastern Russia.

The culprit isn’t wildfire, but deserts.

Western China and southern Mongolia are home to the world’s sixth-largest desert, the Gobi. Surface winds pick up fine particulates at the surface, which are then shot upward into the jet stream. This process can occur all year, but conditions in the spring often create the perfect yellow storm, which leads to definitively imperfect weather on the Asian coast.

When the dust storms reach the coast, they clog the skies and come down in rain showers.

The first recorded instance of yellow dust happened in 1150 BCE, according to the Bamboo Annals, so the phenomenon is not novel. The Gobi is millions of years old, so the movement and deposition of its sand have likely happened for eons.

However, a range of modern conditions has led to a fivefold increase in yellow dust events over the past half century.

The first factor is runaway desertification. The Gobi is expanding rapidly, primarily due to deforestation. More sand and rock equals more yellow dust.

Second, other deserts have joined the fray. And, by other deserts, we mean the Aral Sea. Once the third-largest lake in the world, some scientists now consider the Aral Sea to be defunct. In one of the most stunning, depressing transformations in the modern world, this magnificent body of water began shrinking in the 1960s, but ran toward extinction in the past 30 years.

Satellite imagery of the Aral Sea is hard to believe. Consider 1989 vs. 2014:

This transformation is human-driven. The Soviets dammed and diverted the rivers that led into the basin to irrigate crops across what is now Kazakhstan and Uzbekistan.

The loss of this body poses many local, regional, and planetary problems, one of which is an increase in yellow dust hitting eastern Asia.

However, an increase in intensity and frequency isn’t the only thing worsening for those who experience this sooty rain.

Particulates pick up other things floating around the air and become continental taxis. As the world has become more industrialized, the amount of airborne pollutants has increased starkly. Scientists can analyze what comes down in the yellow dust and, let’s just say, it’s nasty.

In addition to elements you’d expect to see in sand and rock, such as silicon, aluminum, and calcium, they found a slew of toxic components and substances you’d never guess could come down in rain:

Mercury
Cadmium
Sulfur
Soot
Ash
Carbon Monoxide
Chromium
Arsenic
Lead
Zinc
Copper
Pesticides
Fungi
Antibiotics
Herbicides
Plastic
Bacteria
Viruses

Yes, yellow dust can rain down viruses and bacteria.

Scientists assumed these vehicles would be neutralized by long rides under the Sun’s ultraviolet radiation, but apparently this notion needs to be revised.

This phenomenon sounds like something from a fictional, apocalyptic hellscape, but it’s happening right now. And things aren’t getting better. Deforestation continues, which will only hasten the deterioration.

And, if American audiences think yellow dust might not affect them, think again. During the worst storms, when wind patterns are right, the dust commonly reaches Colorado. It can reach the American East Coast.

Trying to remain optimistic while contemplating the Aral Sea and yellow dust is a daunting prospect. The alarms we get aren’t always fire from the sky; sometimes they’re hidden in dust storms we can pass off as natural phenomena.

If we can’t be optimistic, we can try to cope with humor; now, we can add a second part to the old yarn. Don’t eat yellow snow and don’t breath yellow dust.