Glaciers have been found to play a significant role in slowing down climate change by binding large amounts of carbon dioxide (CO2) from the atmosphere. However, a recent study warns that this natural CO2 sink could disappear if glaciers continue to retreat, further accelerating global warming. Researchers from the University of Alberta have discovered that glacier meltwater also binds CO2 from the atmosphere, with some meltwater rivers in the Canadian Arctic binding twice as much CO2 per area as the Amazon rainforest. This is surprising as rivers and lakes typically have a positive CO2 balance. The study found that the meltwater contains fewer organic materials and more minerals, leading to a reaction that effectively binds CO2.
The researchers analyzed the water from Lake Hazen, a 544 square kilometer lake in Canada’s Ellesmere Island, which is fed by meltwater from eleven glacier rivers. They found that the CO2 content of the water was significantly lower than the CO2 equilibrium of the air. The researchers also found that the CO2 saturation of the water decreased the further it was from the point where it melted from the glacier. The decreasing CO2 content was due to chemical weathering triggered by minerals in the water. The weathering reaction constantly removes CO2 from the air to keep the reaction going, leading to a lower CO2 content in the atmosphere.
The researchers estimate that Lake Hazen and its associated rivers bind around a thousand tons of CO2 per year, which is twice as much as the Amazon rainforest per area. The researchers conclude that glacier rivers are an important CO2 sink that has received little attention, despite significantly reducing the CO2 content in the atmosphere. However, the CO2 uptake of glacier rivers and lakes varies greatly depending on the season and only binds large amounts of CO2 with sufficient new meltwater. The study warns that if glaciers continue to retreat, the CO2-binding weathering process will stop, and the natural CO2 sink will disappear.
