Good news—we have more time before the Sun ends life on Earth

It’s a little worrying when a scientific paper begins, “How long will life on Earth last?” But in this case—a study by Jacob Haqq-Misra of Blue Marble Space and Eric Wolf at the University of Colorado Boulder—the proposed multi-billion-plus timeline shouldn’t scare you too much.

The point of this question is that we understand that the Sun will shine as it matures into a red giant that swallows the Earth in a solar furnace. So, where along that 5 billion year path will life on Earth be, in fact, cooked?

Seasons are seasons

This is not a question of incoming radiation. Among the thermostat-like stabilization responses to Earth’s climate, CO cycling₂ through the solid Earth is a big thing in the long run. The heating of silicate rocks on the surface converts the CO gas₂ in the carbonate that ends up at the bottom of the ocean, where it can be absorbed into the mantle by tectonic plates. (And eventually, it can spiral back into space through volcanoes.)

The temperature of the rock depends, among other things, on the temperature. Warmer temperatures and more hydrologic variability mean increased climate, which absorbs CO₂ out of space. That slows down the rise in temperature. But in this case, it can also lead to CO₂ to fall too low – and photosynthesis requires CO₂.

This futuristic marvel has become a staple of many simulations in the game the last few decades. When is the Sun at its brightest, and when is Earth at its hottest or CO₂-and hunger for the food base to survive?

Some of the examples have been simple statistics. Some have been more complex one-dimensional models, representing the sea and the sky separately in mathematics, for example. This new study brings the 3D model to the party and uses scenarios that show different sides of the spectrum.