Plant life on Earth will persist for another 1.8 to 1.87 billion years, according to a study by astrobiologists Jacob Haqq-Misra and Eric Wolf. Using the Exo-CAM 3D climate simulation, the researchers found that resilient species can survive much longer than previous estimates, which placed the end of greenery between 900 million and 1.5 billion years from now.
How Exo-CAM Redefines the Timeline for Plant Extinction
Astrobiologists Jacob Haqq-Misra of the Blue Marble Space Institute and Eric Wolf of the University of Colorado Boulder published their findings in JGR Atmospheres. They moved away from rudimentary climate models in favor of Exo-CAM, a sophisticated 3D simulation that tracks the interplay between Earth’s atmosphere, temperature, and carbon cycles.
Since its birth 4.5 billion years ago, the Sun has grown about a third brighter. The study indicates that within the next 2 billion years, solar luminosity will increase by another 20%.
The Role of Silicate Weathering and CO₂ Depletion
Photosynthesis requires CO₂ to produce energy and oxygen. According to Haqq-Misra and Wolf, the primary threat to plants isn’t just heat, but a process called silicate weathering. This occurs when rainwater reacts with rocks, effectively scrubbing CO₂ from the atmosphere.
As the Sun heats the planet, this weathering process accelerates. Eventually, CO₂ levels drop so low that most plants can no longer perform photosynthesis. This creates a domino effect: without plants, oxygen production ceases, threatening all animal life.
Comparing Old vs. New Extinction Estimates
| Model Type | Estimated Plant Lifespan | Key Driver |
|---|---|---|
| Previous Estimates | 900M to 1.5 Billion Years | General CO₂ decline |
| Exo-CAM Model | 1.8 to 1.87 Billion Years | Resilience of hardy species |
The Survival Threshold: Heat vs. Starvation
The research identifies two potential “endgame” scenarios for Earth’s flora. In the first, the carbon cycle remains highly efficient at scrubbing CO₂, causing plants to starve as the gas disappears from the air.
In the second scenario, CO₂ remains available for longer, but the surface temperature climbs to roughly 65 degrees Celsius (150 degrees Fahrenheit). At this threshold, the heat becomes lethal even for the most durable vegetation.
The study highlights that “hardier species”—specifically certain orchids, succulents, and marine plants—are the reason the timeline extends. These organisms can photosynthesize at much lower CO₂ concentrations than average plants.
Distinguishing Solar Evolution from Modern Climate Change
Haqq-Misra and Wolf emphasize that these findings do not relate to the current human-driven climate crisis. Today’s warming is rapid and caused by anthropogenic emissions. The “slow fade-out” described in the study is a natural result of the Sun’s life cycle occurring over eons.
However, these findings provide critical data for astrobiology. By understanding the limits of Earth’s biosphere, scientists can better predict the “habitable zones” of planets orbiting other stars and determine how long life might persist in those environments.
Even after plants vanish in 1.87 billion years, the study notes that microbial life may persist in deep rocks or soil. The absolute end for complex life occurs later, when the oceans finally evaporate—an event estimated to be another two billion years beyond the loss of plants.
Frequently Asked Questions
When will plants disappear from Earth?
According to the Exo-CAM model, plant life will likely vanish in 1.8 to 1.87 billion years.
What causes the end of plant life?
The Sun’s increasing brightness accelerates silicate weathering, which removes CO₂ from the atmosphere, eventually starving plants of the carbon needed for photosynthesis.
Does this study predict current global warming?
No. The researchers state this is about the Sun’s natural evolution over billions of years, not the current human-driven climate crisis.
Will everything die at once?
No. While plants vanish first, microbes may survive for another two billion years until the oceans evaporate.
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