New Study Projects Earth’s Plant Life to Survive 1.87 Billion Years

New Projections for Earth’s Vegetative Biosphere

A new study published in the journal JGR Atmospheres suggests that plant life on Earth may persist for approximately 1.87 billion years. This estimate represents a significantly longer duration than previous scientific models, which had once suggested that the end of plant life might occur as soon as 100 million years from now.

The research, conducted by astrobiologist Jacob Haqq-Misra and planetary climate scientist Eric Wolf of the Seattle-based nonprofit research institute Blue Marble Space, utilized 29 climate models to simulate the future of Earth’s vegetative biosphere. The study indicates that the ultimate limit on Earth’s plant life is dictated by the Sun’s increasing luminosity, which rises by roughly 1 percent every 110 million years. As the Sun continues to brighten, the resulting thermal stress and atmospheric changes will eventually render photosynthesis impossible.

The Role of Carbon Dioxide and Temperature

The researchers focused on two primary environmental stressors: global temperature and atmospheric carbon dioxide (CO2) levels. Earth’s natural carbonate-silicate cycle typically removes CO2 from the atmosphere, sequestering it into rocks. The study modeled two extreme scenarios to determine how this cycle might influence the survival of plant life:

* Weak Weathering: In this scenario, CO2 levels remain relatively stable, but rising solar luminosity causes global temperatures to increase. The study projects that, under these conditions, the mean temperature on Earth could reach approximately 65 degrees Celsius (150 degrees Fahrenheit), at which point land plants would no longer be able to survive. This model sets the extinction of plant life at roughly 1.87 billion years in the future.
* Strong Weathering: In this model, the Earth’s surface temperature remains stable, but the amount of CO2 in the atmosphere steadily declines as it is locked into carbonate rocks. This leads to a “starvation” scenario for plants. While initial calculations for this model suggested an end to plant life at 1.35 billion years, when researchers applied the threshold of crassulacean acid metabolism (CAM) photosynthesis—used by plants like cacti and orchids—the survival window extended to 1.84 billion years.

Resilience of Photosynthetic Strategies

The study highlights that not all plants will reach their limit at the same time. The duration of survival depends heavily on the type of photosynthesis employed by the organism. While 95 percent of current plant life utilizes C3 photosynthesis, which requires higher concentrations of CO2, plants using C4 or CAM pathways are significantly more efficient. CAM photosynthesis, for instance, requires CO2 levels as low as 1 part per million, allowing such species to endure in much harsher, drier, and hotter environments.

The authors noted that the biosphere’s resilience might exceed current observations. “Life on Earth is resilient, and limits posed by thermal stress or starvation may only reflect our observations of the biosphere today rather than hard limits on how the biosphere may evolve,” the researchers stated.

Context and Limitations

While the 1.87-billion-year projection is a significant finding, the researchers acknowledged several limitations. The study does not account for the potential evolution of plant life, which could develop new mechanisms to regulate temperature or adapt to higher altitudes and different atmospheric compositions. Furthermore, the models do not consider potential human or intelligent technological interventions—such as geoengineering, the use of reflective aerosols, or orbital sunshades—that could theoretically alter the planet’s climate trajectory.

The study concludes that the end of plant life will likely coincide with the period when Earth begins to lose its oceans to space due to the Sun’s increased brightness. Rather than a sudden, catastrophic event, the findings suggest a slow, quiet decline of the biosphere. The authors emphasized that these results should be examined with other 3-D models to further constrain the timescales of Earth’s final chapters.

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