(CNN) In the Mediterranean it is called “Sirocco”, and in the Canary Islands “La Calima”, while it goes by “Harmattan” in West Africa and “Haboob” in Sudan. But these varied names all describe the same thing: dust storms.
Sand and dust storms are a global phenomenon. These fine dust particles can be carried by wind over thousands of miles, affecting health and livelihoods.
According to the UN, dust storms have increased dramatically in recent years due to climate change, land degradation and drought.
Climate scientist Natalie Mahowald hopes that by learning more about dust storms, we can plan for the future. An engineering professor at Cornell University in the US, she has spent the past two decades tracking dust across the globe – and is now working with NASA on a new instrument called EMIT.
First-of-its-kind, space-borne imaging spectrometer helps map dust colors. Scientists can use the data in their climate models to find out how different minerals heat up or cool down the planet, explains Mahowald. Each type of dust has its own unique light-reflecting signature: for example, white dust reflects solar radiation, or heat, while “red and the dark dust absorb it,” she says.
EMIT (The Earth Surface Mineral Dust Source Investigation) will “revolutionize what we can do,” says Mahowald. “We can use that (data) to better understand what the impact of desert dust is.”
A mineral map
Launched in July 2022, EMIT is attached to the International Space Station and orbits Earth 16 times a day, mapping the mineral composition of the planet’s surface by collecting data on spectra, the different wavelengths of light emitted by different colors.
This information allows scientists to determine the mineral and chemical composition of substances on the surface. By scanning 50-mile-wide strips in seconds, the gadget will provide scientists with billions of data points that can be used in climate model predictions — expanding the current data set that comes from just 5,000 sampling sites, Mahowald says.
Most existing data comes from farmland, where detailed soil information was valuable for agricultural and commercial purposes. The wealth of information provided by EMIT, which includes data from the world’s driest regions, will help scientists learn a lot more about dust and its impact on climate – a problem that Mahowald says has been largely overlooked until now.
An evil circle
The UN estimates that 2,000 million tonnes of sand and dust are released into the atmosphere annually.
Sand and dust storms are vital to the planet, carrying nutrient-rich soil across countries and continents and helping plant life to flourish – for example, dust from the Sahara desert feeds trees in the Amazon rainforest, where the soil lacks the necessary nutrients.
“Ecosystems are actually dependent on dust aerosols,” says Diana Francis, a climate scientist at Khalifa University in Abu Dhabi.
But if dust storms become more frequent and intense, they could accelerate global warming: a UN report highlights how changing storm patterns can alter the distribution of Earth’s minerals and reduce rainfall, while dust aerosols can act as greenhouse gases in the atmosphere by absorbing solar radiation.
This can create a feedback loop, where climate change causes more extreme dust storms through land degradation and drought, and dust storms exacerbate climate change. There is evidence that this is already happening, says Francis, pointing to “Godzilla”, the largest global dust storm in 20 years, which crossed the Atlantic Ocean in June 2020, darkening the skies from the Caribbean to the US state of Texas.
Dust storms can cause respiratory diseases, damage livestock and crops and disrupt transport. In the Middle East and North Africa region, they are estimated to cost the economy $13 billion a year.
And the number and severity of storms in the Sahara desert is on the rise, says Francis. In some of her earlier investigations, she found that dust from the Sahara had reached the Arctic, due to changes in atmospheric circulation.
“We noticed that over the last two decades the darkening of the Arctic ice has become significant,” says Francis, highlighting another feedback loop. “We know that when the ice is dark, it will reflect less of the sunlight, and therefore it will melt faster.”
More than just dust
EMIT has delivered 5,000 data sets so far – each containing over 1.4 million spectra. Scientists at NASA use the data to map dust and soil composition across the globe.
But EMIT’s data is also used to map another factor that affects climate change: methane.
Although it makes up only a fraction of greenhouse gas emissions, methane is estimated to have 80 times more heating power than carbon dioxide during the first 20 years after it enters the atmosphere.
Methane absorbs infrared light in a unique pattern, providing a “spectral fingerprint” that EMIT’s imaging spectrometer can accurately identify. While NASA knew EMIT’s imaging technology would be able to detect greenhouse gas emissions, it is performing “better than expected,” said Robert Green, senior scientist at NASA’s Jet Propulsion Laboratory and the principal investigator on the EMIT mission.
So far, EMIT has detected 50 “super-emitters” worldwide, most coming from fossil fuels, waste and agricultural plants, in places including the United States, Iran and Turkmenistan.
While carbon dioxide lingers in the atmosphere for centuries, methane disappears after a decade, meaning that reducing methane emissions is a fast track to slowing climate change. NASA hopes that this information will encourage countries to stop their methane emissions.
While EMIT’s mission was originally planned to last just 12 months, Green says there are now plans to extend the project.
Mahowald is excited about the future. “The EMIT project tests the waters, and really shows what is possible,” she says. “We’re going to go from 5,000 to billions of bits of data, and much higher resolution. That’s going to help us tremendously.”