Fossil Fuels’ Impact On the Most Remote Areas

How Fossil Fuels Impact Atmospheric Chemistry in the Arctic

During my Bachelors Degree in Barcelona, I was granted a scholarship to do a semester in Finland through the Erasmus Program. Back then, I was a very poor student, and all my money was spent in covering my living expenses while completing my undergraduate studies. However, I wanted to so some traveling during my stay.

Among them, I couldn’t miss a trip to Rovaniemi, right at the Arctic Circle and the official home of Santa.

It was an amazing trip! Together with two other friends, we traveled by train, walked around at -32C, met Santa, and had lots of hot chocolate. However, what I remember the most is that feeling that I was in one of the most remote areas on the planet, somewhere where you could lose a sense of time. Somewhere where climate change and pollution weren’t a problem? Well, not so fast! Let’s go to the other side of the Arctic, the American side.

It’s easy to think of the Arctic as a remote, untouched corner of our planet. However, a recent Dartmouth-led study reveals that air pollution from burning fossil fuels is reaching this far-flung region, significantly altering its atmospheric chemistry.

The study, examining ice cores from Alaska and Greenland, points to a dramatic decline in methanesulfonic acid (MSA) — a compound tied to marine phytoplankton activity — and suggests this drop is more about human-driven pollution than any fundamental change in marine life.

Phytoplankton are the foundation of ocean food webs and a crucial component of global carbon cycles. They produce dimethyl sulfide (DMS), which gets oxidized into MSA in the atmosphere.

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For years, scientists have used MSA levels in ice cores as a marker for phytoplankton productivity, interpreting changes in MSA as direct signals of ocean health. But what if the picture is more complex than it seems? This study challenges long-held assumptions, shifting the focus from declining marine ecosystems to how pollutants fundamentally change atmospheric processes. Bear with me; I’ll show you how!

To understand changes in atmospheric chemistry over time, the research team extracted a 700-foot ice core from Denali National Park, Alaska, in 2013. They paired this data with ice-core records from Greenland, going back several centuries.

These ice cores act like a historical record, capturing gases, particulates, and compounds — including MSA — trapped over time. Using modern modeling tools, the team analyzed how changes in industrial emissions and resulting chemical pathways might have altered MSA levels in the Arctic atmosphere.

The turning point came when they noticed a mysterious pattern: MSA levels in Greenland began dropping in the mid-1800s, right when Europe and North America ramped up their fossil fuel burning.

Similarly, MSA levels in Denali stayed steady for centuries until the mid-20th century, when they plummeted alongside the industrial boom in East Asia. It was a puzzle: Why would MSA drop so dramatically in different places and at different times?

For a long time, scientists suspected that declining MSA in ice cores indicated a collapse in phytoplankton populations — one that might be linked to ocean changes like slowing currents or shifts in temperature. But this new study turns that idea on its head. “Our study is a stark example of how air pollution can substantially alter atmospheric chemistry thousands of miles away,” said Dr. Jacob Chalif, the study’s first author.

The researchers found that air pollution, particularly nitrate radicals from fossil fuel emissions, is driving the changes in MSA production. These pollutants alter how DMS is oxidized in the atmosphere, making it more likely to convert into sulfate instead of MSA.

The timeline is telling: as industrialization took off in Europe and North America in the mid-19th century, MSA levels in Greenland ice cores fell significantly.

Fast forward nearly a century, and a similar decline is seen in Alaska, coinciding with East Asia’s industrial expansion. The team noted, “When MSA declines at Denali, nitrate skyrockets,” Chalif explained. “At Denali, MSA is relatively flat for 500 years, no notable trend. Then in 1962, it plummets. Nitrate was similar but in the opposite direction — flat for centuries then spiking upward.”

So, what do MSA really mean?

The findings not only solve a longstanding mystery around MSA levels in the Arctic but also provide a new way of interpreting these ice-core records. Rather than signaling a collapse in marine ecosystems, the declining MSA reflects rising pollution and its effect on atmospheric chemistry.

This is “good news”: the data doesn’t suggest widespread phytoplankton declines. Instead, it points to how human activities, even far from the Arctic, can change what’s happening in these remote environments.

Dr. Jacob Chalif, reflecting on the results, noted, “By releasing all this pollution into the world, we’re fundamentally altering atmospheric processes. The fact that these remote areas of the Arctic see these undeniable human imprints shows that there’s literally no corner of this planet we haven’t touched.”

Why do we say this could signal good news, though?

Well, interestingly, the research uncovered another important takeaway: environmental policies work. When the team examined data from Greenland, they found that after Europe and North America started regulating air pollution in the late 20th century, MSA levels began to recover.

By the 1990s, as nitrogen pollution decreased, MSA rebounded. Nitrogen oxides, the pollutants responsible for altering MSA production, have a relatively short atmospheric life of just a few days, unlike carbon dioxide, which lingers for centuries.

“The good news is that we are not seeing the collapse of marine ecosystems we thought we were,” said Dr. Erich Osterberg, senior author of the study. “The bad news is that air pollution is causing this.” However, the rapid rebound of MSA levels following regulation shows that changes to air quality can have immediate, positive effects.

Dr. Osterberg added, “These data show the power of regulations to reduce air pollution, that they can have an immediate effect once you turn off the spigot.”

Ultimately, while the decline in MSA in Arctic ice cores signals a human impact on even the most remote parts of our planet, it also points to an opportunity for recovery. Effective pollution control measures can — and do — make a difference, offering a path forward for protecting our planet’s atmosphere. Things won’t be easy, but we are on the right path!