How do aerosols move? Fascinating NASA observations and their impact on Earth

When we look up on a clear day, it seems as if there is nothing above us but the sky. In reality, aerosols – particles invisible to the naked eye – are constantly moving through the atmosphere, playing a crucial role in shaping Earth’s climate. Their extraordinary journey across continents can now be observed thanks to a new dynamic map created by NASA scientists.

Six weeks in a minute

Aerosols are unimaginably small – from fractions of nanometers to tens of micrometers, comparable to the diameter of a human hair. Thanks to their high concentration in the air (thousands of particles per 1 cm²), we can track them using satellite images. NASA’s GEOS (Goddard Earth Observing System) combined these observations with ground-based air monitoring data and, through complex computer models, developed a unique map of aerosol movements.

The visualization shows aerosols traveling across Earth’s surface between August 1 and September 14, 2024. During these six weeks, clouds of particles traveled thousands of kilometers, condensed into a one-minute film. Interestingly, this fascinating spectacle also reveals echoes of important events on Earth.

Where does Sahara dust go?

There are many types of aerosols in the atmosphere – from plant pollen to soot. Unlike greenhouse gases, which linger in the atmosphere for many years, aerosols remain airborne only for several days to a few weeks. However, new ones are constantly being emitted.

NASA’s visualization shows four colors of clouds drifting over the oceans: red represents soot, purple stands for Saharan dust, blue for sea salt, and green for sulfates. The latter come mainly from the burning of fossil fuels, but GEOS also highlights clear traces of volcanic emissions over Hawaii and Mount Etna in Sicily.

A purple plume over the Atlantic illustrates the transport of Saharan dust toward the Americas. Indeed, in the summer of 2024, hazy skies and worsened air quality were reported in the Caribbean, Florida, and Texas. Soot aerosols, on the other hand, reflect widespread wildfires in Brazil and Canada, as well as slash-and-burn agriculture in Central Africa.

Also noteworthy are the blue spirals showing sea salt particles kicked up by strong winds. The visualization captures the effects of Hurricane Ernesto over the Atlantic, as well as typhoons Shanshan and Ampil near Japan. NASA experts explain that over the Southern Ocean, salt aerosols are a common phenomenon caused by persistent strong winds, which gave the 40th parallel its nickname, the Roaring Forties.

According to NASA researchers, the visualization aims to make people aware of how aerosols connect distant parts of the world. Events in one region can influence weather and air quality thousands of kilometers away.

Are aerosols good or bad?

On the one hand, aerosols are part of air pollution; on the other, they provide humanity with a huge service. Sarah Doherty from the University of Washington explains that their presence has reduced the rate of climate warming by 0.5°C. How is that possible? Suspended high in the atmosphere, the particles reflect solar radiation, slowing Earth’s warming. Additionally, they act as condensation nuclei for water vapor, fostering cloud formation, which also shields us from the sun.

Here, however, lies an interesting paradox. Reducing greenhouse gas emissions often goes hand in hand with reducing aerosol emissions, which can lead to further temperature increases. According to experts from CarbonBrief, aerosols masked the true pace of climate warming for many years, and it was their recent reduction that contributed to record-breaking heat waves.

What does this mean for the future?

Environmental actions worldwide are consistently reducing aerosol emissions, which is good news for human health. However, unless these changes are accompanied by cuts in methane and other GHG emissions, we face even hotter years and even more extreme weather events.

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main photo credit: NASA’s Goddard Earth Observing (GEOS)