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This article was first published in Castanet Apr 2, 2024
For those of us who work in the field of climate change it is some consolation to take a break and reflect that there are crises worse than global warming.
Giant Meteor: Sixty six million years ago a meteor impact triggered an extinction event that killed most of the dinosaurs. When the meteor hit, it was a double whammy. First, rock fragments triggered fires as far away as 2000 km from the site. Those fires put carbon dioxide, methane and carbon monoxide into the air. Then the impact itself put microdust into the air, blocking sunlight and cooling the planet drastically. Winter-like conditions lasted for two full years and long term effects lowered average temperatures by as much as 15 C over the next 15 years. Less sunlight means less plant life, which means less available food -- scientists estimate that 75% of species went extinct. Don’t worry, a rock this size only hits Earth every 100 million years or so.
Death of the Sun: The sun, our beloved yellow dwarf star, is critical to life on earth. Five billion years from now the sun will begin to run out of fuel. Currently it burns hydrogen, turning it into helium. When the supply of hydrogen gets low it will start to burn helium creating carbon. Fusing helium creates much more heat and this heat will cause the outer layer of the star to puff up and get much larger. Our sun will expand, becoming a red giant, swallowing up Mercury, Venus, and Earth in the process.
Supervolcanos: Earthquakes have the Richter scale and Volcanoes are measured by the volcanic explosivity index (VEI). Vesuvius had a VEI of five and Kracatoa was a six, to name some familiar eruptions. During April 1815 Mount Tambora in Indonesia erupted, with a maximum VEI of 7 on April 10. Approximately 10,000 people were killed as a direct result of the explosion. A further 50,000 in the vicinity of the explosion died of hunger and disease. However, the biggest impact came from worldwide changes in the weather. 1816 is known as “the year without a summer.” Many compounds (such as methane, carbon dioxide and water) increase the atmospheric greenhouse effect, making the earth warmer. However volcanoes release sulfur (in the form of sulfur dioxide and hydrogen sulfide) into the air, where it interacts with hydroxide and water to create sulfuric acid aerosols. These fine droplets reduce the Earth’s temperature by increasing the amount of sunlight reflected back into space. In 1816 so much sulfur was released into the atmosphere that the growing season was ruined -- lower temperatures (including frosts in June, July and August) destroyed crops and crops that survived didn’t receive enough sunlight to thrive. Weather patterns were altered with some regions experiencing flooding and some drought due to changed monsoon patterns. It’s hard to estimate how many people died due to the world-wide knock on effects. Will this happen again? Yes but probably not soon. Some estimates suggest that VEI 7 explosions occur on the time scale of 200-400 years. Volcanoes to watch include Atitlan in Guatemala, Cerro Negro in Chile and Taal in the Philippines.
The Great Oxygenation Event: “The Great Oxygenation Event” took place 2.4 billion years ago during the Paleoproterozoic. Life on earth consisted of single cell organisms which were adapted to a life without oxygen. But then cyanobacteria started to take over. These were the first life forms capable of photosynthesis, (i.e., they could generate energy from sunlight) and photosynthesis took in carbon dioxide and created oxygen. Other life forms found the oxygen to be extremely toxic -- it killed off 96% of the existing species. For the cyanobacteria photosynthesis was a powerful advantage and led to multicelled organisms and eventually to the development of plants and animals. In addition to changing the makeup of the atmosphere, the Great Oxygenation Event changed the climate. The makeup of the atmosphere changed from methane (a strong greenhouse gas) to carbon dioxide (a weaker one) which probably triggered an ice age. The Great Oxygenation Event may be the most significant impact on the environment in the history of the planet.
Articles and cartoons on Teaspoon Energy by Kristy Dyer are licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License You may reprint this as-is for free.
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