How long before sun destroys the Earth? Scientists may have discovered the planet's 'expiry date'

Life on Earth has an expiry date. The end of life on Earth is usually imagined as a dramatic asteroid strike or a catastrophic climate disaster. However, a new study suggests that the real ending is likely to be far slower and far quieter, and every living being, tree, flower and blade of grass on Earth will just die. The question is when. A new study may have an answer to that question.

When will life on Earth end?

Researchers now estimate that Earth’s plant life could survive for about 1.8 billion more years before the planet becomes too hostile for most vegetation to endure. The main reason is simple, and a little unsettling: the Sun is slowly getting brighter.

The study suggests plant life may last almost until Earth begins to lose its oceans and becomes permanently uninhabitable. Long before that, humans and animals were expected to be gone. "Earth's vegetative biosphere could survive up to about 1.8 billion years from now, about the same time that Earth would lose its oceans to space," said researchers.

As that heat rises, Earth will become steadily less forgiving. Temperatures will climb, oceans will shrink, and the atmosphere may eventually lose too much carbon dioxide for plants to make food through photosynthesis. In that future, even hardy vegetation would struggle to hang on.

How did scientists calculate this?

The study, from the University of Colorado Boulder and Blue Marble Space in Seattle, published in JGR Atmospheres, used a three-dimensional climate model to simulate what Earth might look like over the next two billion years. Unlike older estimates, this model took into account not just heat, but also clouds, rainfall, oceans and the movement of the atmosphere. That gave the researchers a more complete picture of how the planet may change.

They tested two main scenarios. In one, carbon dioxide keeps falling as rocks absorb more of it over time. In the other, carbon dioxide stays roughly steady while the planet keeps warming. In both cases, the conclusion was broadly the same: plant life could survive far longer than many previous models had predicted.

The last plants standing would likely be the tough, drought-friendly types, including cacti and others adapted to harsh conditions. Some plants with specialised forms of photosynthesis may also hold out longer than the rest.

Is this "expiry date" final?

No, the study did not factor in how plants might evolve over such vast stretches of time, or how future human technology could change the picture. That leaves room for surprises. The researchers even suggested that plants could one day adapt to hotter conditions, possibly spreading into higher parts of the atmosphere if the environment keeps changing.