For millennia, the Arctic absorbed more carbon than it emitted. That’s changed.

This month, the National Oceanic and Atmospheric Administration released its annual Arctic Report Card. It contained sobering news about the state of the tundra. NOAA reported that after storing carbon dioxide in its frozen soil for millennia, the Arctic is being transformed into a source of carbon in the atmosphere, rather than a sink, or absorber, of the planet-warming element. 

Vox correspondent Umair Irfan, who wrote about this troubling change, spoke with “Marketplace” host Amy Scott about how that could impact the climate crisis and the global economy. The following is an edited transcript of their conversation.

Amy Scott: So for people who aren’t familiar with this region, talk about what the Arctic tundra is. What does it look like? 

Umair Irfan: Well, it’s a region in the northern latitudes. It is a vast, treeless plain. It actually covers about 20% of the planet’s land area, so it’s actually quite large, but the vegetation on there tends to grow very slowly because in the Arctic, of course, the winters are very long. That slow cycle of growth actually gives it this really strong power of being able to capture carbon from the atmosphere and store it for very long periods of time. And the soil beneath it is usually frozen year-round, and so that acts as a critical mechanism stalling the cycle of carbon and making sure it withdraws more than it deposits into the atmosphere.

Scott: So that has changed as the tundra becomes a net emitter of carbon instead of a sink. What is the impact of that, and why has that happened?

Irfan: Well, the planet as a whole has been warming up, and that has had some of its most profound effects in the Arctic regions. The Arctic is actually warming anywhere from two to four times faster than the rest of the planet. But yes, as we’ve seen the Arctic warm, we’ve seen a number of different mechanisms starting to play out, particularly with the soil. The permafrost layer, the year-round, frozen layer of soil, is starting to become less permanent. It’s starting to thaw out in the warmer seasons. And with that, that means microbes in the soil start digesting a lot of the carbon and the vegetation that’s there, and as they do that, they start to emit carbon dioxide and methane. Recently, the National Oceanic and Atmospheric Administration, according to their analysis, they found out that basically, over the past decade, the tundra has now become a net emitter, that there’s more carbon dioxide coming out of the soil, coming out of the tundra, and going into the atmosphere than is being absorbed. That has some pretty important effects for the rest of the planet. Obviously, it means that this ecosystem that we were counting as a sink is now a source, and that can also create more of an amplification and sort of a feedback loop that leads to even more warming. 

Scott: Talk about the role that wildfires play in this. I was surprised to hear how many wildfires have been in the region in recent years.

Irfan: A lot of people don’t seem to associate fire with the Arctic because it tends to be very cold, but fire is a natural part of the ecosystem. We [have] historically seen wildfires in places like the tundra. They don’t tend to be very frequent or happen very often. But more recently, we’ve been seeing the pace of wildfires picking up. That also puts that carbon back into the atmosphere that the vegetation was previously absorbing, and so this increase, this uptick in wildfire activity we’ve seen in the Arctic, is a big reason why we’ve seen this tipping from being a sink to a source in terms of greenhouse gas emissions.

Scott: Wow. Well, I want to talk about some of the economic factors here because as the Arctic warms, there’s just more oil and gas development going on. Is that just going to lead to more warming and kind of feed this cycle?

Irfan: Potentially. You know, the Arctic is — you know, we tend to think of it as this frigid, desolate expanse, but there are about 4 million people that live north of the Arctic Circle. There’s a lot of mining activity already going on there. There are Indigenous communities that live there. It’s also potentially an important shipping route. And of course, with the retraction of sea ice, that means that there’s more resources offshore and onshore that they can access. But crucially, oil and gas development is also driven by the market, and so even though they may have access to the oil and gas that’s available there, it’s still a pretty expensive place to do that kind of extraction work, and it really only makes sense for companies when oil prices are really high. Right now, we have actually kind of an abundance of oil and gas on the global market. So even as this resource becomes more accessible, it’s not a guarantee that companies are really going to be chomping at the bit to try to start drilling. They’re going to probably wait for gas prices to go back up and then maybe start doing more development work there.

Scott: So we hear a lot about this concept of tipping points in climate change, and the thawing of the permafrost is one of those. How frightening is this report card to you, as someone who covers climate change?

Irfan: I would say it’s definitely concerning, but I wouldn’t go as far as to call it frightening. Some of the scientists I talked to were a little wary of using the term “tipping point” here. One of the scientists I spoke to about this actually made the point that, you know, this is potentially still a reversible thing, that if we are able to, you know, limit our output of greenhouse gases, that potentially we could see the balance tip back in the other direction. You know, the past decade has been exceptionally warm and the last two years have been the hottest on record. That doesn’t necessarily mean that the next year will also be even hotter. You know, part of the reason we saw the exceptionally hot years in 2024 and 2023 was because of El Nino, and we expect that fever to sort of break. But the momentum is moving in the direction that the Arctic is becoming less able to absorb carbon over time. That much is definitely true. That does potentially add up to a scenario where we see far more consequential effects, even far south in much lower latitudes, because the Arctic is actually really important for regulating climate and weather in other parts of the planet.