Dust may protect from climate change

The benefits and risks of dust and its role in blocking climate change were explored during a session at the annual scientific meeting of the American Association for the Advancement of Science (AAAS), which took place this year in San Diego, California.

It was one of almost 150 scientific presentations made by some of the world's most accomplished scientists. All offered a chance for people to get up close and personal with the researchers.

The stuff we view as a nuisance when it builds up on surfaces is under intensive study by scientists in fields - including marine and atmospheric science, geology, microbiology and geochemistry. It is increasingly considered when developing computer-based climate models, Prof Joseph Prospero of the University of Miami said.

Dust is defined as airborne soil particles and is not the stuff that arises from burning fuels or industrial pollution. It is whipped into the air by winds that can carry it from places such as the Sahel in north Africa and deposit it across Europe, including Ireland.

We are familiar with this phenomenon, which we notice when our cars are covered in a fine red dust carried up from Africa on southerly winds.

“Dust can affect climate in a number of ways,” Prof Prospero said. It can reflect back solar radiation to reduce global warming on a regional basis and can deliver unexpected benefits by carrying nutrients to replenish soil - a process taking place in the Amazon basin, parts of Hawaii and the Caribbean.

However, after drifting over great distances, the same dust could have health implications, Prof Prospero added. Only the smallest, lightest particles can travel long distances and these can be taken into the lungs when breathing. “We do not know what health impacts these might have,” he said.

The particles can also transport hitchhiking microbes, chemicals and spores, according to Dr Geoffrey Plumlee of the US Geological Survey. Valley fever, for example, is transported across parts of the US by wind when a fungal spore sticks to dust and then gets inhaled.

There are also ecosystem impacts caused by the transport of dust, said Prof Oliver Chadwick of the University of California, Santa Barbara. Dust can build up to smother “desert fringe” plants, which help to hold the desert in check. This causes the desert to spread - in turn delivering more dust to the atmosphere.

However, it also has positive effects, he added, with the dust often carrying nutrients to replenish soils.

Climate change seems set to increase the transport of dust into the atmosphere, Prof Prospero said. Melting land glaciers are releasing large amounts of very fine dust - like talcum - and this could be lifted by the wind.

Source - The Irish Times