Unmasking the Impact: How the Absence of Aerosols Contributed to Rising Temperatures in 2020

Unmasking the Impact: How Cleaner Air Might Have Made 2020 Even Hotter

Okay, so 2020. What a year, right? It’s etched in our memories for a multitude of reasons, and while a global pandemic dominated headlines, something else was brewing in the background: record-breaking heat. In fact, 2020 tied with 2016 as the hottest year we’ve ever seen. And while we all know greenhouse gases are the big bad wolf when it comes to global warming, there was another, sneakier culprit contributing to that temperature spike: a drop in aerosols.

Now, aerosols might sound like something you spray in your hair, but they’re actually tiny particles floating around in the atmosphere. Some come from nature, like volcanic eruptions, but a lot of them are byproducts of human activity, like burning fossil fuels. Here’s the thing: not all aerosols are created equal. Some, like soot, trap heat. But most, especially sulfate aerosols, act like a giant sun umbrella, bouncing sunlight back into space. They even make clouds brighter and more reflective! This has been subtly masking the full force of greenhouse gas warming for years.

Then 2020 hit. Remember those lockdowns? Suddenly, the world went quiet. Factories shut down, cars stayed parked, and planes were grounded. It was eerie, but also, in a weird way, kind of peaceful. But this sudden drop in activity had a side effect: way fewer aerosols were being pumped into the atmosphere. We’re talking about a 40% drop in some pollutants in China and significant reductions in major US cities. It was like the Earth took a deep breath, but the air clearing came with a hidden cost.

And it wasn’t just the pandemic. Around the same time, the International Maritime Organization (IMO) put new rules in place to clean up shipping emissions. For years, ships were burning fuel that was incredibly high in sulfur. Think about it – these massive vessels chugging across the ocean, leaving a trail of pollution in their wake. The new regulations slashed the amount of sulfur allowed in ship fuel by a whopping 80%! That’s fantastic for our lungs, but it also meant fewer of those reflective “ship tracks” – those bright clouds that ships create – were around to deflect sunlight.

So, what happened when we cleaned up the air? Well, we inadvertently pulled back that sun umbrella. All of a sudden, the full force of the sun’s rays was hitting the planet, and temperatures jumped. NASA estimated that this reduction in air pollution caused a warming of up to 0.3°C in some areas. A separate study suggested that the new shipping regulations alone could add another 0.046°C to global temperatures over the next decade. It’s like finally cleaning a dirty window and realizing just how bright the sun really is.

Now, this isn’t to say that cleaning up our air was a mistake. Far from it! Air pollution is a serious health hazard, and we absolutely need to reduce it. But it does highlight the incredibly complex nature of climate change. It’s not as simple as just cutting greenhouse gas emissions (though that’s still the most important thing we need to do!). We need to think about all the different factors that influence our climate, even the seemingly small ones. The Arctic, for example, seems especially sensitive to these changes.

The takeaway? We need a comprehensive plan that tackles both greenhouse gases and aerosol pollution, all while keeping an eye on the potential unintended consequences. We need more research, better climate models, and a whole lot of careful consideration as we move forward. The story of 2020 and the missing aerosols is a stark reminder that when it comes to our planet, everything is connected.