The Earth is about 4.54 billion years old, but according to fossil evidence, fire only appeared a few hundred million years ago due to suitable conditions.
Wildfires in Canada in June 2023. Photo: Reuters
Earth is the only known planet with fire. While there may be volcanoes spewing hot magma on the surface of Venus, the hottest planet in the solar system, fire has never been seen there. Nor has there been fire on Mercury, Jupiter, or any other planet in the solar system or other star systems.
In fact, for a long time in Earth's history, fire didn't exist. It took billions of years for conditions on the planet to become suitable for fire to appear. The first creatures on Earth lived in a world without fire for much longer than is commonly thought. Volcanoes can produce "fire fountains" like those on Jupiter's moon Io, but these are magma forced up and spewed out of vents, not actual fire.
About 2.4 billion years ago, Earth’s atmosphere was likely a thick cloud of methane—the result of bacterial life that had appeared on the planet. Then, during the Oxygen Catastrophe, ancient cyanobacteria began to generate energy from sunlight, releasing oxygen into the atmosphere. This was where molecular oxygen began to accumulate in the atmosphere for the first time, though not in concentrations sufficient for combustion to occur. The Oxygen Catastrophe, also known as the Great Oxidation Event, may have pushed Earth into a global deep freeze because this oxygen destabilized methane and collapsed the greenhouse effect. Earth became cold and fireless.
For vegetation combustion to occur, the amount of oxygen in the atmosphere must be above 13%. But if the oxygen level is above 35%, the fire will burn so intensely that the forest cannot grow and survive. Plants become increasingly flammable as the oxygen level increases, and 35% is the ceiling, beyond which plant biomass will easily catch fire and burn so intensely that it is incompatible with sustainable forest growth.
Around 470 million years ago, during the Ordovician period, the first land plants—the mosses and liverworts—produced more oxygen, eventually reaching concentrations high enough to start fires. Scientists have the first fossil evidence of fire on Earth: charcoal trapped in rocks from about 420 million years ago. But with oxygen levels still fluctuating wildly, large-scale wildfires did not occur until about 383 million years ago. Since then, many devastating wildfires have raged across the planet.
Thu Thao (According to IFL Science )
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