Selasa, 13 Oktober 2020

Dwindling Arctic Sea Ice and Impacts to Permafrost Health - The Arctic Institute

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Permafrost thaw weakens land and creates many pond-like formations in Arctic landscape, like in Hudson Bay, Canada. Photo: Steve Jurvetson

Permafrost thaw is one of the world’s most pressing climate problems, already disrupting lifestyles, livelihoods, economies, and ecosystems in the north, and threatening to spill beyond the boundaries of the Arctic as our planet continues to warm. To examine the effects of permafrost degradation, and increase our understanding of what this phenomenon means for the future of the region (and the world), The Arctic Institute’s new two-part permafrost series aims to analyze the topic from scientific, security, legal, and personal perspectives.


Arctic sea ice and permafrost are not often discussed together, however it appears increasingly important to highlight the relationship between the two. Permafrost refers to frozen ground, which covers nearly one-fourth of the Northern Hemisphere landmass. Arctic sea ice supports the resilience of permafrost, which impacts multiple climate pathways. A study at the University of Oxford determined that past permafrost thaws correlated to time periods with ice-free summers. The research suggested that future Arctic ice-free summers could lead to the destabilization of existing permafrost.

While it is important to consider the immediate impact that an arctic “ice-free” summer may have on the nearby ecosystems, it is even more important to consider the feedback that an “ice-free” summer may have on global climate change. Arctic sea ice is believed to be one of the key factors to maintaining resiliency within local and global ecosystems; without it there could be detrimental effects.

Sea Ice

A reduction in Arctic sea ice has the capability to alter climate and weather patterns, due in part to the amount of available water in the atmosphere. As ice melts, it enters the water cycle and may lead to increased precipitation. In the event of winter precipitation, specifically in the form of snowfall, the land is insulated from the cold temperatures typical in the Arctic. Ground insulation leads to destabilization of permafrost and permafrost thaw.

The National Snow & Ice Data Center (NSIDC) has measured and tracked sea ice extent in the Arctic over the past forty years. Their website includes an interactive data graph, which charts the yearly and monthly variance of Arctic sea ice in million square kilometers. In the comparison of all the available yearly trends, it becomes obvious that the average Arctic sea ice extent has decreased every decade, across all months of the year. Based on the positive correlation between sea-ice and permafrost loss, the average Arctic permafrost is expected to follow a similar trend as the sea-ice, with a noticeable decrease each subsequent decade.

In regard to future decreases in Arctic sea ice, much is uncertain. Predictions of sea ice extent are based on current climate models, which are estimates of the future and verified against the past, but still present some uncertainty. An Arctic summer is said to be “ice free” when the sea ice extent drops below 1 million square kilometers. Some researchers expect that, given the current trajectory, the Arctic may have ice free summers as soon as 30 years from now. This prediction can be verified against data from the Last Interglacial Period (LIG), a period up to 130,000 years before present day. During the LIG, which is believed to be a reliable indicator of future climate change, summer land temperatures were 4-5°C higher than those in the pre-industrial era and the summers were ice-free. Models that include the LIG support the prediction that the Arctic will experience ice-free summers by 2035. In either scenario, there is great concern for the future extent of Arctic sea ice and permafrost.

Permafrost

Permafrost thaw impacts a variety of Arctic systems, including, but not limited to ecosystem balance and the release of greenhouse gases. Soil contains specific ions and molecules, which are stored in the permafrost when frozen. As permafrost thaws, these soil contents become readily available and may move within the environment. If permafrost thaws and there is an increase in summer precipitation, ions and molecules may be displaced from the soil and transported by runoff. Some Arctic lakes were found to have historically high sulfur and chlorine content, which correlated to the key components in the nearby soil. Disruptions to water chemistry can impact the suitable benthic life of the lake, changing the primary plankton type. Soil runoff also has the potential to increase the turbidity of the water source. With these ecosystem changes, there is impact to predatory fish feeding dynamics, along with greater impacts to large animal and human consumers.

Permafrost thawing also has the potential to result in the release of greenhouse gases and increased global warming. As dead plants and animals decay, the remaining organic carbon is accumulated and frozen in the soil. The permafrost is believed to hold at least twice as much organic carbon than the atmosphere; however, as permafrost thaws, these relative carbon concentrations may change. As the frozen ground thaws, soil microbes are then able to decompose organic matter within the soil. The microbial breakdown of soil organic matter is predicted to present increases in atmospheric carbon dioxide and methane gas, two of the primary greenhouse gases, and two large drivers of climate change. Models suggest that during slow, steady permafrost thawing, which is estimated to occur for 80 percent of frozen lands, 200 billion tons of carbon could be released into the atmosphere over the next 300 years. For the remaining 20 percent of frozen lands, which have characteristics that may lead to abrupt permafrost thaw, it is predicted that up to 100 billion tons of carbon could be released into the atmosphere over that same time span. This large amount of carbon release will, in turn, affect global concentrations of greenhouse gases and significantly increase the impacts of climate change, which may include increased temperatures, floods, droughts, agricultural insecurity, and human health threats.

Conclusion

Arctic sea ice is vital to the resiliency of permafrost, along with related Arctic and global ecosystems. A significant loss of sea ice and permafrost has the potential to upset the dynamics of current and future Earth processes. With concern over nearing Arctic “ice-free” summers, and significant permafrost loss, it is important to understand and communicate the potentially expansive effects this occurrence could present.

While sea ice and permafrost loss appears inevitable, research can be conducted to lessen the harmful impacts. Understanding the relationship between sea ice and permafrost may provide key information to better evaluate the dynamics of each individually. Environmental monitoring provides reliable data, which has the potential to track and predict continued thawing events. Discovering methods of mitigation within the ecosystem, and the world at large may help to lessen the harmful impacts of sea ice and permafrost thaws. While there are an estimated 15 to 30 years until the Arctic begins experiencing ice-free summers, these (and other) environmental research efforts cannot wait that long. Arctic communities are already feeling the impacts of climate change, and immediate action is necessary to lessen and slow the progression. To save the Arctic and our planet, we must act now.

Alyssa Burns is a Faculty Research Assistant within the Department of Environmental & Molecular Toxicology at Oregon State University, and beginning her graduate education in Agricultural and Environmental Chemistry at University of California – Davis.

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October 13, 2020 at 02:01PM
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Dwindling Arctic Sea Ice and Impacts to Permafrost Health - The Arctic Institute

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