Reference Terms
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Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. This is the parallel of latitude that (in 2000) runs 66.56083 degrees north of the Equator. Everything north of this circle is known as the Arctic, and the zone just to the south of this circle is the Northern Temperate Zone.
The Arctic Circle marks the southern extremity of the polar day (24 hour sunlit day) of the summer solstice in June and the polar night (24 hour sunless night) of the winter solstice in December. Within the Arctic Circle, the Sun is above the horizon for 24 continuous hours at least once per year, in conjunction with the Arctic's Summer Solstice. Likewise, in conjunction with the Arctic’s Winter Solstice, the Arctic sun will be below the horizon for at least 24 continuous hours.
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Earth & Climate News
October 31, 2025
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Oct. 29, 2025 — Global scientists warn that humanity is on the verge of crossing irreversible climate thresholds, with coral reefs already at their tipping point and polar ice sheets possibly beyond recovery. The Global Tipping Points Report 2025 reveals how rising ...
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Oct. 29, 2025 — Beneath the ice of Antarctica’s Weddell Sea, scientists discovered a vast, organized city of fish nests revealed after the colossal A68 iceberg broke away. Using robotic explorers, they found over ...
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Oct. 27, 2025 — The Southern Ocean absorbs nearly half of all ocean-stored human CO2, but its future role is uncertain. Despite models predicting a decline, researchers found that freshening surface waters are currently keeping deep CO2 trapped below. This ...
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Oct. 26, 2025 — New research shows that hippos lived in central Europe tens of thousands of years longer than previously thought. Ancient DNA and radiocarbon dating confirm they survived in Germany’s Upper Rhine Graben during a milder Ice Age phase. Closely ...
Oct. 26, 2025 — Scientists have uncovered that glaciers can temporarily cool the air around them, delaying some effects of global warming. This self-cooling, driven by katabatic winds, is nearing its peak and will likely reverse in the next two decades. Once ...
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Oct. 30, 2025 — A new species of mountain lizard, Diploderma bifluviale, has been discovered in the upper Dadu River Valley of China. Its distinct traits and isolated habitat highlight the hidden biodiversity of the ...
Oct. 28, 2025 — Fungi’s evolutionary roots stretch far deeper than once believed — up to 1.4 billion years ago, long before plants or animals appeared. Using advanced molecular dating and gene transfer analysis, ...
Oct. 28, 2025 — Scientists have traced the origins of complex life to the breakup of the supercontinent Nuna 1.5 billion years ago. This tectonic shift reduced volcanic carbon emissions, expanded shallow seas, and ...
Oct. 27, 2025 — New research shows that the rise of Sumer was deeply tied to the tidal and sedimentary dynamics of ancient Mesopotamia. Early communities harnessed predictable tides for irrigation, but when deltas ...
Oct. 27, 2025 — A massive crater hidden beneath the Atlantic seafloor has been confirmed as the result of an asteroid strike from 66 million years ago. The new 3D ...
Oct. 27, 2025 — Researchers traced tremor signals deep inside Tanzania’s Oldoinyo Lengai volcano, pinpointing their 3D locations for the first time. The study ...
Oct. 23, 2025 — In the mist-shrouded mountains of New Guinea, a Czech researcher has achieved a world-first — capturing photos, video, and data of the elusive Subalpine Woolly Rat, Mallomys istapantap. Once known ...
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