Image: NASA

The Arctic is our planet’s refrigerator. It’s also warming six times faster than the global average.

The Arctic’s snow and ice reflect much of the light that reaches it, helping to keep the planet cool. As the planet warms, ice melts and the Arctic reflects less light. Warmer temperatures also mean that permafrost, or soil that is frozen year-round, begins to thaw out. When it does, frozen organic matter begins to decay, releasing carbon dioxide and methane into the atmosphere, which intensifies the greenhouse effect, leading to more warming, which leads to more permafrost thawing and… you get the point. 

This cycle, called permafrost climate feedback, drives the higher rates of warming at the poles. Arctic permafrost contains twice as much carbon as the atmosphere. A melted Arctic would release this carbon into the atmosphere, leading to catastrophic effects for the entire planet. 

So, we need to keep the Arctic frozen. But how?

A study in Nature  by Yating Chen and her colleagues at Beijing Normal University examines a radical solution: increase albedo in the Arctic to prevent warming and permafrost thawing by preventing sunlight from entering the atmosphere. 

Known as solar geoengineering, this strategy aims to mimic the cooling effects of a volcanic eruption by injecting sulfur compounds into the atmosphere. These compounds reflect some sunlight back into space before it has the chance to enter the atmosphere.  

Solar geoengineering is controversial partly because the effects of sulfate injection are under researched. But don’t worry; Chen’s study is just a simulation. By using what we know about environmental processes, Chen and colleagues  built an earth system model that mimics the conditions of life on earth, then manipulate the conditions to predict the future. This study uses a geoengineering model that’s popular because it models a sudden injection of sulfates into the atmosphere. If we embrace geoengineering only as an emergency solution to climate change, sulfate injection will probably happen quickly as a last-ditch attempt to save the world, so this model is realistic.

In addition to modeling sulfate injection, this study incorporates a moderate emissions reduction framework that projects the climate stabilizing at a global average of 1.8 degrees Celsius warmer. This keeps our climate just under the 2 degrees C of warming that has come to represent a point of no return for the global climate. If the climate stabilizes at 2 degrees C, the models predict that 40% of Arctic permafrost will melt. Under moderate emissions reductions, 35% would melt. With the sulfate injections, this figure plummets to just 15%.

Putting a price tag on the Arctic is tricky, but the permafrost climate feedback could result in  $13.8 trillion (trillion, with a tr) in economic losses, even under the reduced-emissions scenario. Sulfate injection would help save about $8.4 trillion. 

There’s still a lot we don’t know about sulfate injection. What are the ecological impacts of more atmospheric sulfur? How would people living in the Arctic, especially Indigenous communities, be affected? What does maintenance look like? What would happen if a solar geoengineering project was suddenly interrupted? 

Critics raise these questions to discredit geoengineering, but the immensely promising results of this study should spark interest in more research using models to explore the effects of sulfate injection. Nobody can predict the future with certainty, but models can give us a pretty good guess. 

There is no silver bullet to stop climate change, but this study shows that the combination of reduced emissions and sulfate injection are key in preventing permafrost thawing. Stabilizing the climate is a daunting task, but the Arctic is a good place to start.