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The future of Earth on Venus

A recent study by space researchers at Rice University poses a troubling scenario could the surface of the future Earth become a deadly inferno just like the planet Venus? According to a Rice University news announcement, the study suggests that prolonged heating of Earths atmosphere might shut down the process of plate tectonics and cause a planets crust to become locked in place. The heat required goes far beyond anything we expect from human-induced climate change, but things like volcanic activity and changes in the Suns luminosity could lead to this level of heating, said Adrian Lenardic, associate professor of Earth science at Rice University. Our goal was to establish an upper limit of naturally generated climate variation beyond which the entire solid planet would respond. U.S. and Russian space probes have discovered that Venus evolved differently from our home world, although it may have had hot water oceans very early in its history. While Venus and Earth are near twins in size, Venus has an oppressive, highly dense carbon dioxide-saturated atmosphere. In fact, Venuss violent, murky atmosphere gave rise to the now-famous term greenhouse effect. The term was coined by NASA astronomer Carol Sagan after the space agencys Mariner-2 spacecraft detected it in 1962. The Venusian atmosphere is about 100 times denser than Earths. Its so dense, in fact, that surface features would appear blurry as if underwater to a visiting astronaut. The planets smothering blanket also makes the surface temperature far hotter than that of Mercury. Mercury is twice as close to the Sun as Venus, yet its hottest surface temperature is nearly 200 degrees cooler than our nasty planetary twin! One dynamic process that seems unique to Earth, at least in our solar system, is our planets crustal plates, or tectonic plates. Seafloor carbon, mostly the remains of living organisms and other matter, gets recycled through the Earths interior thanks to these mammoth tectonic plates. The plates help sequester carbon and return it to the mantle as a result, CO2 doesnt build up in the atmosphere as rapidly. But the dynamics of plate tectonics doesnt happen on Venus. Sometime in the dim past, plate tectonics came to a halt on Venus. Perhaps this mighty geological process never even got started in the first place scientists are unsure on this point. So what would happen if the subduction and recycling of Earths crustal plates came to a grinding stop? And could the process ever stop? We found the Earth's plate tectonics could become unstable if the surface temperature rose by 100 degrees Fahrenheit or more for a few million years, Lenardic said. The time period and the rise in temperatures, while drastic for humans, are not unreasonable on a geologic scale, particularly compared to what scientists previously thought would be required to affect a planet's geodynamics. Lenardic said that the stress generated by Earths flowing mantle keeps the big plates in motion. But when you add rising atmospheric temperatures, the result deep inside the mantle is akin to overheating a bowl of oatmeal in a microwave oven. When enough heat is applied, tectonic plates dry out and crack while their movement is shut down. Thats probably exactly what happened on Venus eons ago. Lenardics team concluded that the atmospheric heating needed to shut down the movement of Earths crustal plates is far less than once believed. Whats in the Sky: During the evening of Nov. 20, the giant ringed-planet Saturn can be seen near the rising Moon. Saturn appears as a brilliant distant diamond shining in the night sky. Lou Varricchio. M.Sc., is a former NASA senior science writer. He is a member of the NASA/JPL Solar System Ambassador program in Vermont and a senior member of the Civil Air Patrol, an auxiliary of the U.S. Air Force.

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