The climate conference in Brazil (COP30) ended without breakthrough agreements, and meanwhile the sun continues to do what it has done for billions of years: sending rays to Earth.
The way these rays interact with the atmosphere largely determines what happens to our climate.
We have all heard of greenhouse gases, but few know that alongside them exists another, much smaller but important player: particles.
These include tiny grains of smoke, dust, and soot that float in the air and change how sunlight behaves.
Some particles scatter light and cool the atmosphere, others absorb it and warm it.
A new study revealed how tiny smoke particles from fires in the Amazon affect the climate crisis.
A Whole World of Particles
“One of the factors in climate change that still carries a lot of uncertainty is the issue of particles in the atmosphere,” explains the lead researcher, a postdoctoral fellow at Stanford University. “
We can say that the impact of greenhouse gases on the climate is very harmful, and for some other factors we know their effect is positive or negative.
But for particles: we do not even know if their impact is ‘good’ or ‘bad’.”
“There are particles that are considered more ‘natural,’ like sea salt, which is so light that the wind spreads them throughout the atmosphere.
This is what we call the ‘smell of the sea,’ and inhaling them is beneficial for health,” he explains. “On the other hand, fires emit many particles that are very harmful to human health.
The same applies to particles from cars and various industries.
There is a whole world of particles, and because they are so diverse in diameter, chemical composition, and color, their effect on the atmosphere and radiation is also very varied.
Large and light particles scatter sunlight and prevent it from reaching the ground. Small and dark particles absorb sunlight and heat the atmosphere.”
To better understand how particles affect the climate, the researcher and the team went to one of the areas where the air is still relatively clean from urban pollution but heavily influenced by fire smoke: the heart of the Amazon rainforest.
There, inside the enormous tropical forest, perhaps one of the last places where nature still seems stronger than humans, delicate but powerful processes occur that affect the entire system.
Fires Devastating the Amazon Trees
“In the Amazon, many natural processes involve different types of particles.
For example, pollen and even sand grains from the Sahara cross the ocean and reach there.
All these are an important source for enriching the forest soil, which is naturally poor in nutrients. These are natural processes that have been occurring for millions of years,” the researcher explains. “In recent decades, these fires have intensified due to human interventions in the area, such as deforestation.
When vast areas of the Amazon burn each year, it changes the entire particle balance. This affects rainfall and its distribution in the Amazon and changes everything.”
The Surprise of Black Carbon
The team sampled the air, examined the particle composition, and checked how each type changes the radiation balance: how much light is scattered and how much is absorbed.
Scattering means light does not reach the ground directly but spreads in the atmosphere, reducing the amount of heat accumulated on Earth.
Absorption leads to warming, while scattering cools relatively.
The findings showed that small, dark particles, especially black carbon the classic particle released by fires can significantly affect the heat accumulated on Earth, even when they are only a small part of the total particle mass in the air.
The surprise came when the team sampled areas thousands of kilometers away from the fires to understand the broader impact.
Particles take several days to travel from the fire zone to the measured area.
Along the way, they absorb other gases and liquids, changing shape, size, and even chemical composition.
The study found that black carbon continues to absorb radiation very efficiently but also becomes the main contributor to scattering radiation, which was a novel discovery.
The Amazon Burns Again
The researcher emphasizes that this does not mean black carbon emissions from fires are positive. “One could cynically say ‘it’s not so bad to burn the forest because it not only heats the atmosphere but also cools it.’
No the message is absolutely not to burn the forest. But if a fire occurs, we need to understand the consequences.”
“The better we understand these processes, the more accurately we can model climate change, and accordingly, define what actions are required from us.
Satellites constantly measure particles across the globe, and to improve satellite data, ground measurements like ours are used.
Our ultimate goal is to understand Earth’s processes: both human-made and natural.
We need to account for many parameters.
For example, when looking at greenhouse gases and ways to reduce their emissions, we do not necessarily know how reducing a certain amount of CO2 will affect natural processes over time.
The more accurate the data we put into global models, the better we can define our goals and the actions needed to reach them.”