• Kendall Plein

Largest Arctic Expedition Reveals Looming Point of No Return

Many scientists look to specific environmental markers and possible tipping points to determine the likelihood of potential recovery in studying the changing climate. But the outlook is dim following MOSAiC, the largest Arctic expedition in history that took place between September 2019 and October 2020, led by Alfred Wegener Institute scientist Markus Rex.

Credit: Pixabay/David Mark

“We won’t succeed in accurately forecasting climate developments if we don’t have reliable prognoses for the Arctic,” said Rex.

Arctic sea ice is a standard marker for climate change’s impact. The concept is easy to understand: as the climate becomes more unstable and global average temperatures warm, the ice at the planet’s north and south poles begin to melt. However, the more rapid the rate of ice loss, the closer the Earth’s climate comes to sustaining permanent damage.

The 389-day Arctic expedition brought proof of the Arctic’s death spiral at the hands of climate change. Rex and his team collected ice samples and data on the atmosphere, ocean, and ecosystems. The most haunting discovery was the state of the Arctic’s summer sea ice.

The Descent into Melt

The mental image of the Arctic is one of ice and snow, but that reality changes dramatically as seasons shift. In the winter, from November to March, the Arctic is bathed in darkness. It is cold and windy, and the sea ice starts to develop. In March, the Arctic sea ice reaches its farthest extent before melting as summer starts. As the Arctic warms, the ice extent begins to shrink.

Climate scientists have been tracking the Arctic’s sea ice for decades. Since 1979, we have seen a downward trend in the extent of the summer sea ice. The loss of ice is attributed to anthropogenic or human-caused climate change. The increased greenhouse gases in the atmosphere create a warming trend, especially at higher latitudes. Since 1979, scientists have seen thinner ice, less new ice production, and a smaller extent of Arctic sea ice.

While the image of a polar bear floating on a small iceberg may be the most common imagery of climate change, the melting Arctic has many more global impacts. Several climatic systems are affected by the warming Arctic, and they all have positive feedback loops — a vicious cycle where changes to a system intensify over time.

Arctic Amplification isn’t Stopping

As the Arctic warms, the system reacts in ways that intensify the heating. The main positive feedback loops in the Arctic include the albedo effect, methane release, increased water vapor, and warming rivers.

The Arctic sea ice acts as a giant mirror to the sun’s rays. The sun’s rays reflect off the white surface and then exit the atmosphere. The ice reflects about 50% of incoming solar radiation, which prevents those rays from warming the region. The less amount of reflective ice there is, the more the dark-colored Arctic Ocean absorbs solar radiation. As the ocean warms, the water isn’t cool enough to support new ice formation, and the ice sheet stays underdeveloped. This perpetuating cycle makes the proposition of preserving the remaining sea ice daunting.

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As the Arctic summer ice melts, parts of land once covered in ice and permafrost start to thaw. Permafrost covers the Arctic tundra, and if it thaws, it releases methane. Methane is a greenhouse gas with 23 times the warming potential of carbon dioxide. As the permafrost thaws, methane is released into the atmosphere. The methane then contributes to more warming and thus more permafrost melt.

Several north-flowing rivers deposit into the Arctic Ocean. Those waters are generally warmer than the seawater in the Arctic, and with climate change, they are becoming more so. The warm river water that flows into the Arctic Ocean further warms the waters and contributes to sea ice melt.

Point of No Return?

Rex worries that humanity has already set off an explosive process we cannot stop. He discovered that sea ice was disappearing faster than previously thought, most likely due to the positive feedback loops impacting the Arctic. The sea ice was half as large as it was in 2010 and was 10 degrees warmer than in the 1890s. Rex said that in the upcoming years, we will know if we have passed the tipping point in the Arctic.

The numerous positive feedback loops involved in the Arctic’s climate warrant more concern than currently paid. In addition to the warming effects, the melting ice causes sea levels to rise and ocean currents to be disrupted. Melting Greenland ice releases 300 cubic kilometers (72 cubic miles) of water into the ocean. This water is freshwater, which disrupts the salinity of the North Atlantic Ocean. The freshwater slows the Gulf Stream as it moves south to Florida. The weakening of the Gulf Stream has many more negative effects and can change the weather on both sides of the Atlantic.

There are several environmental tipping points scientists have noted. Due to the complexity of the Earth’s biogeochemical systems, it’s hard to identify the point of no return. However, scientists have an idea of possible areas that could drastically alter the planet.

The melting of Arctic sea ice may seem simple; as the planet warms, the ice melts. However, there are greater systems that have the power to alter the entire climate of the Earth. Melting sea ice is not only a result of climate change but a cause as well. Without immediate and extensive action, it may prove impossible to mitigate the dire effects of climate change.


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