Earth’s atmosphere is much more dusty than previously thought.

Dust is a key component of Earth’s climate system. When it interacts with clouds, oceans, and radiation from the sun, it has a general impact on our planet’s living systems, affecting everything from weather and rainfall to global warming.

There are two types of dust in the atmosphere, both raised by high-speed winds in dry areas. Fine dust tends to cool down because it scatters sunlight, just like clouds. Coarse dust, which is larger in size and originates from places like the Sahara desert, tends to heat the atmosphere, as do greenhouse gases.

Knowing precisely how much thick dust is in the atmosphere is essential to understanding not only the atmospheric phenomena that influence dust, but also the degree to which dust may be heating the planet.

Now, UCLA scientists report that there is four times the amount of coarse dust in Earth’s atmosphere as currently simulated by climate models. Their findings appear in the magazine. Scientific advances.

The researchers found that Earth’s atmosphere contains 17 million metric tons of coarse dust, equivalent to 17 million elephants or the mass of each person in the United States.

“To adequately represent the impact of dust as a whole on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere,” said first study author Adeyemi Adebiyi, a postdoctoral researcher at the Department of Atmospheric and Oceanic at UCLA. Sciences and recipient of the Postdoctoral Scholarship of the President of the University of California.

By connecting this missing amount of coarse dust in the models, Adebiyi said, it increases the likelihood that the overall net amount of dust, both fine and coarse, will heat up rather than cool the Earth’s climate system from the air. to the oceans.

Coarse dust particles heat the entire Earth’s climate system by absorbing both incoming radiation from the sun and outgoing radiation from the Earth’s surface. These particles can affect the stability and circulation within our atmosphere, which can affect atmospheric phenomena such as hurricanes.

Adebiyi worked with Jasper Kok, an associate professor of atmospheric and ocean science at UCLA, to determine the actual amount of coarse dust in the atmosphere by analyzing dozens of published aircraft-based observations, including recent measurements taken over the Sahara desert. , and comparing those with half a dozen widely used global atmospheric model simulations.

“When we compare our results with what current climate models predict, we find a drastic difference,” Kok said. “Next-generation climate models represent just 4 million metric tons, but our results showed more than four times that amount.”

Furthermore, Adebiyi and Kok found that thick dust leaves the atmosphere less quickly than current climate models predict. Air tends to mix more turbulently when dust is present. In the case of the Sahara, air and dust mix in a way that pushes the dust upward, which can act against gravity and keep dust in the air much longer, they said.

The scientists’ findings also show that because dust particles remain in the atmosphere longer, they eventually settle further away from their source than these models predicted or explained in current theory. Dust particles ejected from the Sahara, for example, can travel thousands of miles in the atmosphere, reaching the Caribbean and the United States.

When desert dust ends up in the oceans, it can boost the productivity of ocean ecosystems and increase the amount of carbon dioxide absorbed by the oceans.

Due to the way coarse dust interacts with energy from the sun and clouds, it can also have a big impact at the time of precipitation, as well as the amount or little rain that falls.

“Models have been an invaluable tool for scientists,” said Adebiyi, “but when they miss most of the thick dust in the atmosphere, they underestimate the impact that this type of dust has on the critical aspects of life on Earth, from precipitation to cloud cover ocean ecosystems at global temperature. ”