Research in the Amazon has shown that black soot particles emitted by fires can become the most significant component of radiation scattering; ground measurements are also used to calibrate satellite measurements and improve climate crisis predictions
Maya Falah, Angle - news agency for science and the environment
Climate Conference (COP30) ended without any groundbreaking agreements, and in the meantime the sun continues to do what it has been doing for billions of years: send rays to Earth. The way the rays meet the atmosphere largely determines what happens to our climate. We have all heard of greenhouse gases, but not many know that alongside them there is another, much smaller but important player: particulate matter. These include, among other things, tiny grains of smoke, dust, and soot that float in the air and change the way the sun's rays behave. Some of the particles scatter the light and cool the atmosphere, while others absorb it and heat it. New research Discovered how tiny smoke particles created by fires in the Amazon are affecting the climate crisis.
A whole world of particles
"One of the factors in the field of climate change about which there is still a lot of uncertainty is the issue of particles in the atmosphere," explains lead researcher Dr. Raphael Stern, a graduate of interface program And currently a postdoctoral fellow at Stanford University in the United States. "We know that the impact of greenhouse gases on the climate is very bad, and there are other things that we know have a more or less good effect. But as for the particles: we don't even know whether the effect is 'good' or 'bad,'" says Stern.
"There are particles that are viewed as more 'natural,' for example, like the salt in the sea, whose particles are so light that the wind picks them up and disperses them throughout the atmosphere. This is actually what we call 'the smell of the sea,' and when we breathe them in it is excellent for our health," he explains. "On the other hand, when there is a fire, for example, a lot of particles are emitted that are very bad for our health. The same goes for the particles emitted from cars and various industries. There is a whole world of particles, and because they are so diverse and so different, in their diameter, their chemical composition, and their color, their effect on the atmosphere and radiation is also very diverse. If the particles are large and bright, then they scatter the sun's radiation and prevent this radiation from reaching the surface of the Earth. If they are small and dark, then they absorb the radiation and heat the atmosphere," he says.
To better understand how particles affect the climate, Stern and his research team went to one of the places where the air is still relatively clean from urban pollution, but is greatly affected by smoke from fires: The heart of the Amazon forestThere, within the vast tropical forest, perhaps one of the last places where it still seems that nature is stronger than man, subtle but powerful processes take place that affect the entire system. "In the Amazon, there are a lot of natural processes that involve many different types of particles. For example, flower pollen and even grains of sand from the Sahara cross the ocean and get there. All of these are a very important source of nutrition for the forest's soil, which is naturally poor in nutrients (nutrients, MP). These are natural processes that have been happening for millions of years," explains Stern.In decades The latest These fires have become very intense. Because of various human interventions in the area, such as deforestation. When every year Huge areas of the Amazon are burning."It changes the entire balance of particles. It affects, for example, the amount of rain and its distribution in the Amazon, it changes everything," he says.
The surprise of black coal
As part of the study, the team modeled the air, examined the composition of particles, and examined how each type changes the radiation balance: how much light is scattered and how much is absorbed. Scattering radiation means that light does not reach the ground directly, but is scattered in the atmosphere, which actually reduces the amount of heat that accumulates on Earth. In other words, while the absorption of radiation leads to warming, scattering of radiation is a process that cools relatively.
The findings showed that the small, dark particles, especially those belonging to black carbon – the classic particle emitted by fires – can significantly affect the heat that accumulates on Earth, even when they are only a small part of the total mass of particles in the air. So far, not too many eyebrows have been raised, but then came the surprise. "We chose to sample in an area thousands of kilometers away from the fires to understand how the fires affect the wider range," says Stern. "It takes the particles several days to get from the fire area to the area we measured. In the meantime, they absorb all kinds of other gases and liquids along the way, which causes them to change their shape, size and even their chemical composition. What we discovered is that black carbon continues to be very effective at absorbing radiation, but in addition, it becomes the most significant factor in scattering radiation, which is a novelty."
Stern emphasizes that the message is not that black carbon emissions from incinerators are positive. "You can take this very cynically and say, 'Look, it's not that bad to burn the forest because it not only causes the atmosphere to heat up, but also contributes to its cooling.' So no – our message is absolutely not to burn the forest. But if there is a fire, then you need to understand what the consequences are," he says.
"The better we understand these processes, the better we will be able to produce Accurate models "More for predicting climate change, and accordingly we will be able to better define what is required of us. For example, there are satellites that remotely measure particles all over the Earth all the time. To improve the measurements from the satellites, they use measurements from the ground like the ones we do. Ultimately, our goal is to understand the processes that are happening on Earth: processes that are man-made and natural processes. We need to take into account so many parameters. When we look at greenhouse gases, for example, and look for ways to reduce their emissions, we don't necessarily know how reducing a certain amount of carbon dioxide will affect all kinds of natural processes in different ranges. The more we know and the more accurate data we are able to put into global models, the better we will be able to define where we are aiming and what we need to do to get there," he concludes.
More of the topic in Hayadan:
