Written by: Hasnaa H. Abo Shosha
Edited by: Jessica Li
This piece was written in collaboration with the 2025 ComSciCon-MI Write-A-Thon.
I was amazed when I first learned that something as small as a particle of soot could shift the Earth’s climate. These particles are so tiny that you could line thousands of them across a single strand of hair. And yet, they have the power to change how much of the Sun’s energy warms our planet. I like to often think of them as invisible sun catchers floating in the sky.
Scientists call them aerosols—tiny solid or liquid bits suspended in the air. You’ve seen them before without realizing it: in the haze of city smog, the smoke from a campfire, or even sea salt sprayed from ocean waves.The fact that these aerosols behave differently makes them more fascinating. While some act like mirrors, scattering sunlight back to space and cooling the Earth, others act like sponges, soaking up sunlight and heating the atmosphere.
One type of aerosol I focus on in my research is black carbon, commonly known as soot. It’s produced whenever fuel burns without being fully consumed—whether from cars, factories, or even forest fires. Black carbon is dark, so it absorbs sunlight very efficiently. It’s like wearing a black T-shirt under the summer sun versus a white one: The black shirt would absorb more light energy as heat, so you feel hotter compared to someone wearing a white shirt.. Now, imagine the Earth’s atmosphere wearing that the black carbon like a shirt, it absorbs energy from the sun and warms up the Earth’s temperature. This is besides its effects on the lungs and health.
Now here’s where it gets more interesting black carbon doesn’t float around alone, so it often ends up inside cloud droplets. Normally, clouds are like bright white blankets in the sky, reflecting sunlight back into space and keeping the Earth cool. But when black carbon gets trapped inside these droplets, it changes the cloud’s behavior. Instead of reflecting light, the cloud starts to absorb more of it. Scientists describe this effect in terms of radiative forcing—which refers to how much the Earth’s energy balance is nudged toward warming or cooling. Black carbon almost always tips the scale toward warming.
This warming isn’t the same everywhere. Over the ocean, where the surface is dark and already absorbs a lot of sunlight, adding more absorption in the atmosphere above can really heat things up. Over snow or ice, even a little black carbon can have a huge effect, because it makes reflective surfaces less able to bounce sunlight away. This helps explain why the Arctic is warming faster than many other regions.
What fascinates me most is how something so tiny can affect big systems like the oceans, storms, and ice sheets. Black carbon in the atmosphere can shift rainfall patterns, change how clouds form, and even affect the intensity of storms over the ocean. When it falls to the ground and darkens the snow, it speeds up melting. The same particles that harm our lungs when we breathe polluted air are also reshaping the climate system we all depend on.
This dual impact—on health and climate—is why black carbon matters so much. The good news is that unlike carbon dioxide, which can stay in the atmosphere for centuries, black carbon only lingers for days to weeks. This means that reducing black carbon emissions can bring almost immediate benefits. So making better choices like cleaner cookstoves, better fuel use, and limiting open burning can improve the air we breathe and slow the pace of warming at the same time.
When I step back and think about my research, I often picture clouds as storytellers. Each droplet carries a trace of our human activity—sometimes pure water, some other times carrying soot. Together, they shape whether the story they tell is one of cooling or warming. And though we can’t see these particles with our eyes, they are silently writing the next chapter of our climate’s future.
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