Have you ever wondered how the world will end? Well we will be swallowed by the sea. Earth’s continental crust which forms the land we live on has been slimming down according to a new estimate. It’s believed that the land will disappear some years to come.
Currently scientists and environmentalists are focused on the rising sea levels and atmospheric carbon but the crust is left out. But if we survive all that, the slow flattening of continents could end our world. As the continental crust erodes, land would disappear into the oceans even without climate induced sea level rises.
Script writers and movie directors have taken advantage of this scientific fact to make spectacular science fiction movies.
“I’m thinking Waterworld.” Bruno Dhuime of the University of Bristol, UK, who led the study said. Dhuime’s team collated measurements of 13,000 rock samples from around the world. They found that in rocks from the Andes and Central America where continental crust is forming the amount of silicon and the relative concentrations of rubidium and strontium isotopes are related to the thickness of the crust that the rocks had come from.
“This relationship can allow us to estimate the thickness of crust at different times in the past,” Dhuime said. Continents today are about 35 kilometres thick, on average, with the buoyant rock bobbing next to the 7-kilometre-thick, denser oceanic crust, which rides lower. But before about 3 billion years ago, Dhuime thinks, the continents were slimmer. Having less volume made them less buoyant, meaning they couldn’t float up above sea level.
“If it continues for the next 2 billion years, then the crust will again reach that state where the continents are submerged beneath the ocean,” Dhuime says.
“There are a lot of assumptions and models in here,” says Clark Johnson of the University of Wisconsin-Madison. For example, he says, for the continents to get thinner in the long term, erosion would have to also outpace magma that attaches to the base of the crust – not just the build-up of crust at plate convergences that Dhuime’s team considered.
Researchers believe that the earth’s crust may have shrunk over the past hundred million years. This idea is built on looking at subduction zones, where two plates come together and one slides beneath another.
NewScientist reports that the first bloom of life on Earth happened at about the same time as the first rise of earth’s crust, when shallow seas could host algae, about 2.5 billion years ago. According to Dhuime’s model, land was just starting to peek out of the water and now it might be slowly headed back in that direction.