How is dust from Europe’s largest desert impacting the climate?

Understanding High-Latitude Dust could help to predict global warming and weather patterns.

Scientists are delving into the world of sand to better understand its impact on our climate and weather systems.
But the location of their research might surprise you.
Iceland is the largest and most active desert area in Europe, but instead of orange sandy dunes, its 44,000 km2 desert areas are flat, barren expanses of black volcanic dust. Like regular deserts, they produce sand that can lead to powerful dust storms in windy weather.
These particles are known as ‘high latitude dust’ (HLD), as they come mainly from regions near the Arctic Circle, though they can reach as far as mainland Europe. 
Each type of dust has a unique fingerprint according to the material that makes it: the Icelandic particles one is made of black volcanic glass.
“We found Icelandic black dust in Finland, but even Serbia,” says Pavla Dagsson-Waldhauserova, a researcher at the University of Agriculture of Iceland and president of the Icelandic Aerosol and Dust Association.
The UN ranks desertification “among the greatest environmental challenges of our time”, as climate change and man-made activities turn lush areas into dust planes.
Icelandic deserts are a result of human activity. “This area would have been a birch forest,” says Dagsson-Waldhauserova, pointing at the barren landscape. Viking settlers tried to cultivate the land using techniques suited to Northern Europe, but these methods proved ineffective in Iceland’s colder, windier climate.
The country’s  landscapes have degraded over centuries, and today, only about 2 per cent of Iceland is covered by forest or woodland. 
While some scientists believe that the Arctic may eventually become green and lush once more, reforestation in Iceland is progressing slowly and with modest aims. The Icelandic Forest Service (IFS) hopes to be able to increase the nation’s forest cover to 4 per cent by 2050. 
Once desertification has started it’s difficult to reverse: there are about 135 days per year when dust rises from the Icelandic desert and contaminates other areas in Europe or Iceland that have not yet desertified. Volcanic eruptions pump out more ash, intensifying desert conditions.
The climate implications of HLD differ significantly from those of low-latitude dust. The IPCC considers brighter Saharan and Asian desert dust beneficial in one way, as it reflects light. 
But Icelandic dust particles are darker, meaning they absorb the sunlight and so warm up the land and air.
“The most important impact on the climate is the depositing [of dust] on the cryosphere,” says Dagsson-Waldhauserova, pointing at the Myrdalsjokull glacier in front of us. When the black sand creates a layer of up to 1.3 centimetres on glaciers, the heat it collects melts the ice.
She monitored the glacier degradation for more than two years thanks to the COP21-funded Planet Watch project which provided cameras to monitor 10 glaciers worldwide. 
Similar to black coal, this dust is a significant air pollutant and driver of climate change in fragile Arctic regions. Because of its reach, glaciers in Greenland and the sea ice are also impacted, Dagsson-Waldhauserova says.
With glaciers melting faster due to increasing temperatures, more dust is becoming exposed. “Underneath the glacier, you have the finest mountain material, an unlimited source of dust,” she explains.
Dagsson-Waldhauserova monitors active dust hotspots and is developing a more accurate regional dust model, with the help of several measuring instruments stationed across Iceland. 
Thanks to the Copernicus Monitoring programme (CAMS), she has just finished a first year of permanent dust observation. “The problem with global dust models is that they do not have HLD sources included or the resolution is too low. Our in-situ data should help the dust modellers to tune their models,” she tells Euronews Green.
An estimated two billion tonnes of sand and dust enter the atmosphere every year, limiting visibility and causing health problems like respiratory illnesses. 
The risks are still underestimated: “While only two people have lost their lives due to volcanic eruptions in the past 150 years, dust storms have produced hundreds of deaths in accidents in Iceland,” says Dagsson-Waldhauserova. 
High-latitude dust has potential cooling effects too. 
Airborne dust can create more clouds in the sky by serving as nuclei for ice crystals, a process critical for cloud formation. “Even just a handful of dust particles can have a massive impact on the way a cloud forms and its lifetime,” explains Polly Foster, a PhD student at the UK’s University of Leeds who is investigating this impact.
The unique composition of HLD, with its darker colour and high mineral content, makes it particularly effective at forming clouds filled with ice or water. 
Clouds strongly influence the Earth’s climate through a process called cloud-climate feedback. 
They are essential for the water cycle and play a key role in controlling the Earth’s temperature by affecting how much solar energy is reflected back into space and how much heat is trapped. 
“If we can understand the amount of dust that is getting up we will be able to predict clouds better, which in turn can help us predict global warming and weather patterns much better,” Foster says.
To unlock this mystery scientists need to discover how particles are distributed at different heights in the sky. 
Foster is trialling a new method to determine particle presence: “We’ve maybe figured out a way to be able to define it. That is something that nobody has ever done, and that is really exciting and really important,” she says.
The team are using a meteorological drone to reach different heights. “Our drone measures temperature, pressure, humidity, two-dimensional winds, but also particle size and number of particles in real-time and it can go up to two kilometres,” says Ben Pickering, chief meteorological officer at drone company Menapia.
So far only weather balloons and laser light instruments called lidar can measure the atmospheric boundary layer (ABL) – Earth’s lowest.
“The ABL is very critical for making weather forecasting more accurate because it is where all energy exchange happens, and it is where air pollution can be trapped,” Pickering adds. 
But while weather balloons are very expensive to fly and only collect measurements twice per day, and lidar can only fly in clear weather conditions, drones are a cheap and reliable option.
Foster attaches an innovative instrument to the drone which can collect particles at very low quantities on a glass slide, providing unparalleled insights into dust behaviour and transport. 
Meanwhile particles are collected with the same instrument at ground level to compare glass slides. “If the results come back positively and we can show the way that dust has been transported up, it would be incredible,” she says.
Reporting for this story has been supported by a science journalism award from the European Geosciences Union.