Alaska’s vast, frozen landscapes have long been recognized as an essential carbon sink, trapping organic material within its permafrost. However, pioneering research from the University of Texas at Austin has revealed a secret source of carbon emissions that may be hastening climate change. According to the study, Alaska’s Groundwater is releasing massive amounts of carbon into oceans, particularly around the Beaufort Sea coast.

While groundwater accounts for only a small portion of total water entering the ocean, it provides an estimated 230 tonnes of organic carbon each day during the summer—equivalent to the carbon produced by the region’s rivers. This underappreciated carbon transport mechanism has long-term implications for ocean chemistry and global CO₂ levels. As Arctic temperatures rise, permafrost thawing is predicted to accelerate, increasing groundwater runoff and exacerbating climate change. The carbon-rich outflow contributes to global carbon emissions and jeopardizes marine habitats by accelerating ocean acidification. These findings underscore the importance of conducting additional studies on groundwater’s role in the carbon cycle and addressing the complex and interwoven effects of climate change.

A Silent Contributor to Climate Change

According to a revolutionary study from the University of Texas at Austin, a small amount of Alaska’s Groundwater is releasing massive carbon into oceans, possibly contributing to climate change. While groundwater accounts for only a small portion of total water released into the sea, it is expected to release approximately 230 tonnes of organic carbon each day over the almost 2,000-kilometer coastline of the Beaufort Sea during the summer months. This amount of carbon is comparable to that released by free-flowing rivers in the same region over the same time period.

Cansu Demir, who led the study while pursuing her doctorate at the UT Jackson School of Geosciences and now works as a postdoctoral research associate at Los Alamos National Laboratory, emphasized the magnitude of carbon emission. “This study shows that there are humongous amounts of organic carbon and carbon dioxide released via fresh groundwater discharge in summer,” according to Demir.

The findings, published in Geophysical Research Letters, provide new insight into groundwater’s involvement in carbon cycling and its consequences for climate change. As climate change accelerates the thawing of Arctic permafrost, carbon emissions from coast to sea are predicted to increase dramatically. Demir cautions that this outflow could turn the surface waters into a source of CO₂ for the atmosphere. Furthermore, CO₂ emitted from groundwater discharge may worsen ocean acidification, affecting marine habitats and endangering many aquatic species.

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The Discovery of a Major Carbon Pathway

One of the most noteworthy parts of this study is that it gives direct observational evidence of fresh groundwater discharge into the ocean near the coastline, which was previously considered rare in the Arctic. Prior to this study, researchers believed that freshwater contributions in this region were primarily limited to river runoff and melting ice. The study is also notable for its ability to distinguish between fresh groundwater and recirculated saltwater. Unlike previous studies, which included groundwater mixed with saltwater seeping from the coast, this study isolates freshwater sources such as rains, snowmelt, thawed ground ice, and maybe permafrost melt. Using direct observations, numerical modeling, thermal analysis, and hydraulic methodologies, the researchers calculated that fresh groundwater entering the Beaufort Sea accounts for around 3-7% of total water discharge from the region’s three major rivers in the summer.

Although groundwater’s volume is minor compared to river flow, it contains a comparable quantity of organic carbon and nitrogen, making it an essential but hitherto ignored component of the Arctic’s carbon cycle. “In that small amount of water, groundwater carries almost the same amount of organic carbon and nitrogen as rivers,” she said. Groundwater moves beneath the surface, passing through soils and sediments before reaching the ocean. It collects organic debris, inorganic substances, and nutrients along the journey. When it interacts with permafrost, it absorbs even more carbon, transforming it into an underground reservoir of organic matter.

Permafrost, which works similarly to an underground estuary, contains large amounts of frozen biological matter. As it melts and mixes with groundwater, it releases large amounts of carbon into marine environments. “The Arctic coast is changing right in front of our eyes,” said Bayani Cardenas, a study co-author and professor in the Jackson School’s Department of Earth and Planetary Sciences. “As permafrost thaws, it forms coastal and undersea aquifers. Even without the thawing, our findings are among the first to demonstrate the presence of such aquifers directly.”

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Environmental Implications: From Ocean Acidification to Coastal Ecology

The ramifications of this discovery go beyond climate change. Alaska’s Groundwater is releasing massive carbon into oceans and could significantly impact coastal ecosystems. One of the most alarming results is ocean acidification, which occurs when CO₂ dissolves in saltwater and lowers its pH. Acidification can make marine ecosystems unfavorable to many species, particularly shell-forming creatures like crabs, clams, and snails. As these organisms struggle to create and retain their shells in more acidic conditions, their populations may drop, upsetting the food chain and impacting larger marine predators that rely on them for survival.

Furthermore, rising carbon levels in coastal waterways may promote algal blooms, exacerbating ecological imbalances. Excess organic carbon and nitrogen can encourage the growth of phytoplankton, resulting in hypoxic zones—low oxygen levels that are harmful to marine life. These changes could have far-reaching consequences for Arctic biodiversity, fisheries, and indigenous groups that rely on marine resources for survival and cultural customs. The study emphasizes the need to monitor Arctic groundwater discharge and its impact on both local and global ecosystems. Given that the Arctic is warming approximately four times faster than the rest of the planet, the ongoing thawing of permafrost and associated increase in groundwater flow may aggravate carbon emissions to coastal waterways.

In conclusion, as the world’s climate difficulties worsen, identifying hidden sources of carbon emissions, such as subsurface groundwater flow, becomes increasingly important. This study not only changes our understanding of the Arctic carbon cycle but also emphasizes the importance of more comprehensive climate mitigation measures that account for lesser-known sources of greenhouse gas emissions. The findings warn that even seemingly insignificant natural processes can seriously affect the planet’s future.

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