Rock weathering drives further warming in the Arctic

An unexpected and obscure phenomenon in the Arctic could dramatically accelerate climate change: the weathering of rocks.

This natural process in the Canadian Arctic could potentially trigger a feedback loop, accelerating the release of carbon dioxide (CO2) into the atmosphere as global temperatures continue to rise.

Arctic rock weathering

Rock weathering is a process where certain minerals and rocks react with oxygen in the atmosphere. This results in a series of chemical reactions that ultimately release CO2.

As an example, the weathering of sulfide minerals – like fool’s gold – produces an acid that forces CO2 out of other rock minerals.

The scary part? This largely overlooked weathering process is increasing in the Arctic because of rising temperatures.

The Arctic is warming nearly four times faster than the global average, which means we urgently need to understand the potential contribution of CO2 emissions from rocks.

Until recently, our knowledge about the response of rock weathering to changing temperatures. as well as the amount of additional CO2 that could be released. was quite limited.

Alarming acceleration of Arctic weathering

A recent study has provided some fascinating insights. The investigation focused on 23 sites across the Mackenzie River Basin, Canada’s largest river system.

The researchers examined the sensitivity of sulfide weathering – the process behind these CO2 emissions – to rising temperatures. They used records of sulfate, a product of sulfide weathering, to trace the speed of the process.

The findings were alarming. Over the past 60 years, from 1960 to 2020, as temperatures increased by 2.3°C, sulfide weathering increased by 45 percent. This suggests that the CO2 released could trigger a feedback loop, accelerating warming in the Arctic.

Dramatic increases in sulfide oxidation

Drawing from past river records, the researchers forecasted that by 2100, carbon dioxide released from the Mackenzie River Basin could double to 3 billion kg/year under a moderate emission scenario.

To put this into perspective, this would be equivalent to half the total annual emissions from Canada’s domestic aviation sector.

“We see dramatic increases in sulfide oxidation across the Mackenzie with even moderate warming,” said study co-author Dr. Ella Walsh.

“Until now, the temperature sensitivity of CO2 release from sulfide rocks and its main drivers were unknown over large areas and timescales.”

What’s more, not all parts of the river catchment were affected equally. Weathering was much more sensitive to temperature in rocky mountainous areas and those covered with permafrost.

Conversely, regions blanketed with peatland showed lower increases in sulfide oxidation with warmth because the peat protects the bedrock.

Sulfide weathering and climate models

The implications of this study, conducted by experts in the Department of Earth Sciences at the University of Oxford, are far-reaching beyond the Mackenzie River Basin.

Similar environments across the Arctic – characterized by rock types, high proportions of exposed bedrock, and extensive permanently frozen ground – could also see rapid increases in sulfide weathering.

According to the researchers, this highlights the urgent need to consider sulfide weathering in large-scale emission models, which are extremely useful for making climate change predictions.

As we continue to grapple with the impacts of climate change, understanding these lesser-known factors and their potential to accelerate the process is more important than ever.

Building ecosystem resilience in the Arctic

Given the potentially widespread effects of sulfide weathering, leveraging the natural resilience of Arctic ecosystems may provide a partial solution.

Arctic regions contain unique biomes, like tundra and peatland, which can act as natural carbon buffers. These ecosystems not only absorb CO2 but also moderate temperatures and shield underlying bedrock from rapid warming.

Expanding conservation efforts to protect these areas could help slow down the feedback loop triggered by sulfide weathering.

Addressing the issue also requires international cooperation. The Arctic spans multiple countries, each facing unique challenges as climate change accelerates.

Collaborative research initiatives, involving Arctic nations and global scientific organizations, could help standardize monitoring practices and improve data-sharing on sulfide weathering.

By pooling resources and expertise, these partnerships can enhance predictive models, leading to more effective climate policies.

Furthermore, an increased focus on reducing global greenhouse gas emissions remains essential. While the impact of sulfide weathering is significant, its long-term consequences will depend on the overall trajectory of global warming.

The study is published in the journal Science Advances.

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