03:08 PM Sunday 03 December 2023
How long will Earth exist?
In empty time, the sun is a primary source of gravity and energy. But one day, it will cause the Earth to disappear.
So, how much time does it have until the sun engulfs our planet?
Expected time of the end: several billion years from now. But life on Earth will end much sooner than that.
Scientists tell Live Science that the Earth will become uninhabitable for most living organisms in about 1.3 billion years due to the natural evolution of the Sun.
Humans could easily drive themselves to extinction within the next few centuries if the current pace of human-induced climate change is not mitigated.
Earth will likely have 4.5 billion years before the Sun becomes a large red giant and then engulfs Earth, said Ravi Kopparapu, a planetary scientist at NASA’s Goddard Space Flight Center.
A red giant forms in the final stages of stellar evolution, when a star runs out of hydrogen to fuel its nuclear fusion and therefore begins to die, according to the European Space Agency.
Once fusion stops, gravity takes over. The helium core will begin to compress under gravity, which will raise the temperature. This increase in temperature will cause the Sun’s outer plasma layer to expand significantly. “The Sun will swell at least to the size of Earth’s orbit,” Kopparapu said.
Earth’s fate
But the Earth probably won’t last those 4.5 billion years, and it certainly won’t be the Earth as we know it.
“You don’t have to wait for the sun’s outer layers to reach Earth,” he said. The planet will experience intense heat long before the Sun finishes becoming a red giant. As the Sun’s temperature rises due to its dying process, “the oceans will evaporate, the atmosphere will eventually disappear, and then the tidal forces caused by the Sun’s gravity will tear apart the Earth.”
About 1.3 billion years from now, humans “will no longer be able to survive, physiologically, in nature” due to persistent hot and humid conditions. In about 2 billion years, the oceans may evaporate when the Sun’s luminosity is about 20% greater than it is now, Kopparapu said.
Some life forms may survive up to that point — such as “extremophiles” that live near hydrothermal vents on the ocean floor — but not humans, Kopparapu said.
Humans — and all complex life forms — are in dire need of this, Rodolfo Garcia, a doctoral student in astronomy and astrobiology at the University of Washington, told Live Science. He added that for humans, for example, an increase of only 3.3 degrees Celsius is life-threatening.
Kopparapu said dangerous humid temperatures — a combination of temperature, humidity, wind speed, sun angle and cloud cover — at which humans can no longer cool down by sweating are very imminent, just a few degrees away.
The wet-bulb threshold for humans was first predicted to be 35°C, but more recent research suggests that wet-bulb temperatures as high as 30°C can be lethal.
Some places on Earth have already reached humid temperatures exceeding 32°C on multiple occasions, and climate models predict that 35°C will be a regular occurrence in regions such as the Middle East by the end of the century.
The Middle East is a geopolitical term that refers to the region of the Levant, the Arabian Peninsula, Anatolia, Egypt, Iran and Iraq.
At this temperature, animals that sweat would cook in the heat, Kopparapu said. In essence, our greenhouse gases are poised to threaten life and society on Earth long before the sun dies.
“If we are talking about human life, the next 100 years will be interesting,” Kopparapu said.
