12 Times Earth’s Atmosphere Almost Killed Us All

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Environmental

By Trista - October 1, 2025

Earth’s atmosphere serves as a vital shield, protecting life from harmful cosmic radiation and space debris. However, its volatile history reveals instances where this protective layer has nearly led to catastrophic events. From massive explosions to near-miss asteroid impacts, these occurrences underscore the delicate balance between Earth’s atmosphere as a safeguard and a potential threat. Understanding these events highlights the importance of monitoring and preserving our atmospheric integrity to ensure the continued survival of life on our planet.

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1. The Great Oxygenation Event

12 Times Earth’s Atmosphere Almost Killed Us All — 2.1-billion-year-old rock showing banded iron formation. Source: Wikipedia

Approximately 2.4 billion years ago, cyanobacteria began producing significant amounts of oxygen through photosynthesis, leading to the Great Oxygenation Event. This surge in atmospheric oxygen was toxic to many anaerobic organisms, resulting in widespread extinctions. The event also led to the formation of banded iron formations as excess oxygen reacted with dissolved iron in the oceans. This pivotal period significantly altered Earth’s atmosphere and set the stage for the evolution of aerobic life forms. (britannica.com)

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2. The End-Permian Mass Extinction

Around 252 million years ago, the End-Permian Mass Extinction, also known as the “Great Dying,” was precipitated by massive volcanic activity in the Siberian Traps. This event released vast amounts of carbon dioxide and sulfur dioxide into the atmosphere, leading to a runaway greenhouse effect. The resulting global warming and ocean acidification caused the extinction of approximately 90% of marine species and 70% of terrestrial vertebrates. (news.mit.edu)

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3. The Medieval Famine and Climate Anomalies

Between 1315 and 1317, Europe experienced the Great Famine, a catastrophic event triggered by severe climatic anomalies. Unusually heavy rainfall during the spring and summer of 1315 led to widespread crop failures, as grains failed to ripen and fields became waterlogged. This resulted in soaring food prices and mass starvation, with mortality rates escalating due to malnutrition and disease. The famine’s severity was exacerbated by the Little Ice Age, which brought cooler temperatures and further disrupted agricultural productivity. The crisis had profound social and economic impacts, including increased crime, social unrest, and a significant decline in population. (en.wikipedia.org)

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4. The Little Ice Age

Beginning in the 14th century, the Little Ice Age was a period of cooler global temperatures that lasted for several centuries. This climatic shift led to shorter growing seasons and harsher winters, severely impacting agriculture and economies. Crop failures became more frequent, resulting in widespread food shortages and increased mortality rates. The cooling also contributed to the expansion of glaciers in Europe and North America, altering landscapes and human settlements. (scientificamerican.com)

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5. The Ozone Hole Crisis

In the late 20th century, scientists discovered a significant depletion of the ozone layer over Antarctica, known as the ozone hole. This thinning allowed increased ultraviolet (UV) radiation to reach Earth’s surface, posing serious health risks such as skin cancer and cataracts, and threatening ecosystems. The global response led to the 1987 Montreal Protocol, an international treaty aimed at phasing out the use of ozone-depleting substances, marking a pivotal moment in environmental protection efforts. (wwf.org.au)

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6. The 1783 Laki Volcanic Eruption

In 1783, Iceland’s Laki volcano erupted, releasing approximately 120 million tonnes of sulfur dioxide into the atmosphere. This led to a dense haze across Europe, causing respiratory issues and increased mortality. In Iceland, the eruption resulted in the death of over 50% of livestock and a significant portion of the human population due to famine and disease. The global climatic effects included cooler temperatures and crop failures, highlighting the profound impact of volcanic activity on Earth’s atmosphere and life. (pnas.org)

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7. The Killer London Smog of 1952

In December 1952, London was enveloped by the Great Smog, a severe air pollution event that lasted from December 5 to December 9. A combination of cold weather, an anticyclone, and windless conditions trapped pollutants—primarily from coal combustion—over the city. This led to a dense, toxic fog that reduced visibility to mere meters and seeped indoors. The smog resulted in approximately 4,000 deaths and left 100,000 people ill, highlighting the severe health impacts of air pollution. (metoffice.gov.uk)

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8. The Bay of Bengal Cyclone, 1970

On November 12, 1970, the Bay of Bengal Cyclone, also known as the Bhola Cyclone, struck East Pakistan (now Bangladesh) and India’s West Bengal. Forming over the central Bay of Bengal on November 8, the cyclone intensified rapidly, reaching peak winds of 185 km/h (115 mph) by November 10. It made landfall on November 12, bringing with it a devastating storm surge that inundated the low-lying Ganges-Brahmaputra delta region. The surge led to widespread flooding, resulting in an estimated 300,000 to 500,000 fatalities, making it the deadliest tropical cyclone on record. The cyclone’s impact was particularly severe in the Tazumuddin area, where over 45% of the population perished. The disaster highlighted the vulnerability of the region to such natural events and underscored the need for improved disaster preparedness and response strategies. (britannica.com)

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9. The Mount Tambora Eruption of 1815

In April 1815, Mount Tambora in Indonesia erupted catastrophically, releasing vast amounts of volcanic ash and aerosols into the atmosphere. This debris formed a global haze that blocked sunlight, leading to a significant drop in global temperatures. The following year, 1816, became known as the “Year Without a Summer,” characterized by unseasonably cold temperatures and widespread crop failures. These climatic disruptions resulted in mass starvation and economic hardship worldwide. (nationalgeographic.com)

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10. The Sudden Peaking of Carbon Monoxide in the Donora Smog, 1948

In late October 1948, Donora, Pennsylvania, experienced a severe air pollution event when a temperature inversion trapped emissions from local steel mills and a zinc smelting plant. This led to a dense, toxic smog that enveloped the town for five days, causing respiratory distress in thousands and resulting in at least 20 fatalities. The incident highlighted the dangers of industrial pollution and spurred the clean-air movement in the United States. (smithsonianmag.com)

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11. The Present Climate Crisis

The ongoing climate crisis is characterized by escalating greenhouse gas emissions, leading to rising global temperatures and more frequent extreme weather events. Between 2030 and 2050, climate change is projected to cause approximately 250,000 additional deaths annually due to undernutrition, malaria, diarrhea, and heat stress. (who.int) Sea levels are rising, threatening coastal communities with increased flooding and erosion. (en.wikipedia.org) The urgency of addressing these challenges is underscored by the United Nations’ warning that current climate policies may lead to a global temperature increase of over 3 degrees Celsius by 2100, far exceeding the targets set by the Paris Agreement. (reuters.com)

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12. The Toxic Clouds of Lake Nyos, 1986

On August 21, 1986, Lake Nyos in Cameroon experienced a catastrophic limnic eruption, releasing approximately 100,000 to 300,000 tons of carbon dioxide (CO₂) gas. This dense, colorless cloud rapidly descended into surrounding valleys, displacing oxygen and suffocating over 1,700 people and 3,500 livestock within a 25-kilometer radius. The victims were found without signs of struggle, indicating sudden asphyxiation. This rare phenomenon highlighted the potential dangers of volcanic lakes and led to the implementation of degassing systems to prevent future occurrences. (usgs.gov)

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Conclusion

Throughout history, humanity has been profoundly affected by atmospheric phenomena, from ancient mass extinctions to modern climate crises. Our increasing understanding of atmospheric science has enhanced our ability to predict and mitigate these events, improving our resilience. However, challenges persist, underscoring the need for continued research and proactive measures to safeguard our future. Ongoing efforts in climate science and adaptation strategies are crucial in addressing the evolving threats posed by our planet’s dynamic atmosphere. (science.nasa.gov)

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