In March 2026, Arctic winter sea ice reached one of the lowest levels ever recorded, measuring 5.52 million square miles. This is approximately 10% below the 30-year average. It was a decline of 10,000 square miles compared to the 5.53 million square miles recorded in 2025. The sea ice coverage was 5.56 million square miles in 2017 and 5.79 million square miles in 2020, showing a continuous decline.
The reduction in white ice leads to more dark ocean water, which absorbs heat instead of reflecting it, potentially accelerating warming. However, sailors know that the ocean rarely appears black, except under a moonless sky. Light typically reflects off the sea much like it does off the sky, although a cloudy sky can make the ocean seem a gunmetal gray.
Science involves observing, questioning, recording, and sharing. Consider an experiment using two pint glasses on a sunny day—one filled with cold black coffee, the other with cold white milk. By placing thermometers in each, you can observe changes over time.
Both liquids will eventually match the air temperature through conduction, with the glass making contact with the air. Unlike a black car seat, water molecules in the liquid can move freely. This chaotic movement makes it impossible to heat water above room temperature with a hair dryer. Dark ocean waters do not warm from sunlight and are not responsible for melting sea ice; instead, they warm through contact with warmer surfaces, similar to a coffee pot on a stove.
The Arctic Ocean is linked to the Atlantic Ocean via the Greenland Sea. The Svalbard Archipelago lies between these two oceans. To Svalbard’s east is the Barents Sea, covering roughly 540,000 square miles and located north of Norway and Russia, west of Franz Josef Land. On the continental shelf, it is relatively shallow, averaging about 750 feet, while the Arctic Sea to the north has an average depth of approximately 3,900 feet.
The Arctic does not melt uniformly like a spring pond. Melting begins with warm Atlantic Gulf Stream water. Almost all the Arctic Sea ice loss, totaling 525,000 square miles, occurs in the Barents Sea, part of the Arctic Ocean. This is due to the Coriolis Effect, caused by the Earth’s eastward rotation, which makes water flowing north curve to the right. Thus, warm Atlantic water flows directly into the Barents Sea.
In April 1810, the whaler William Scoresby lowered a ten-gallon wooden cask made of fir into the depths after wintering in the Greenland Sea west of Svalbard. This design was by Joseph Banks, the scientist on Cook’s expedition. Fir was chosen for its superior insulation. Scoresby discovered that Gulf Stream water at 100 to 200 fathoms was six to eight degrees warmer than the Arctic water above. Initially skeptical, he modified the cask for quicker temperature readings, confirming the results. The Gulf Stream flowed into the Arctic Ocean, separated from the sea ice by denser, less salty Arctic water.
Scoresby also noted climate changes linked to human activities like draining marshes, felling woods, and agriculture. Over time, the loss of vegetation and soil, replaced by heat islands, has led to warmer stormwater runoff into the Atlantic without altering annual rainfall. This strengthens the Gulf Stream, and as temperatures rise, the expanding water nears the surface in the Arctic.
In 2007, the Gulf Stream surfaced in Svalbard, melting glaciers on land. During the winter of 2010-2011, it was observed to meander closer to Rhode Island than ever before, suggesting a need for it to dissipate more energy.
The Gulf Stream flows past New Jersey at 30 to 40 Sverdrups (30 to 40 million cubic meters per second), with a seasonal variation of 5-15%. Maximum flow typically occurs in late summer to early fall. It gathers more water as it travels north, transporting over 100 Sverdrups east of the Grand Banks off Newfoundland. Only 2-3% of the total Gulf Stream flow reaches the Barents Sea via the Norway Current, yet it greatly impacts Arctic climate.
Atlantification, the process by which warm Atlantic water melts Arctic sea ice, results in thinner winter sea ice that melts faster in summer. NASA imagery shows the Siberian coast from Norway to Alaska opening almost simultaneously. The Atlantic water entering the Arctic forms a counter-clockwise gyre, pushing ice against Canada and Northern Greenland.
Rounding Greenland, the Arctic Ocean current moves south along Greenland and into the Denmark Strait between Iceland and Greenland. Here, cold, nutrient-rich Arctic water meets warm, nutrient-poor Atlantic water and plunges 11,500 feet down. This creates the Earth’s largest waterfall, three times taller than Angel Falls, but underwater.
The East Greenland Current becomes the Labrador Current after rounding Greenland, carrying oxygen-rich and nutrient-rich waters into the Atlantic. The Grand Banks off Newfoundland compel Arctic waters to mix with warm, salty water, forming a highly productive fishing region.
The Northeast Passage, the Arctic Ocean sea route from the Atlantic along Siberia to the Pacific, opened in the early 2000s. In 2007, the Northwest Passage through the Canadian Arctic Archipelago also opened to shipping. The close timing of these openings was unexpected, considering our understanding of oceanography. However, solar radiation from Canadian Shield rocks allowed this in a region unreachable by Atlantic water.
To restore the Arctic’s winter sea ice and cool the climate, we should reduce surface runoff by increasing vegetation cover and soil depth, keeping water on land where it falls. Additionally, providing more shade and transpiration cooling from plants can lessen the heat island effects of structures. Slowing water flow during abundance ensures it’s available when and where nature needs it, reducing seasonal ocean warming.
Increasing water on land brings immediate benefits like more greenery, less warming, and decreased ocean swelling. The advantages for land, water, and sky are vast and complicated, but restoring Arctic sea ice is clear and calls for responsible local actions by all property owners, regardless of their location in Earth’s watershed.
About the Author
Dr. Rob Moir is a nationally recognized and award-winning environmentalist. He is the president and executive director of the Ocean River Institute, a nonprofit based in Cambridge, MA, that provides expertise, services, resources, and information not readily available locally to support the efforts of environmental organizations. Please visit www.oceanriver.org for more information.
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