Researchers have calculated a much longer survival timeline for plant life on Earth. A study published in JGR Atmospheres estimates that the planet's vegetation could persist for up to 1.9 billion more years, until environmental changes make photosynthesis impossible. Led by Jacob Haqq-Misra and Eric Wolf of Blue Marble Space, the research examines how the Sun's gradual brightening and declining atmospheric CO₂ will eventually end the era of green life on Earth.
The study sets out two basic scenarios. In the first, the Sun's growing brightness steadily raises Earth's surface temperature. Over the next 1.5 billion years, average temperatures could climb by more than 20 degrees Celsius. Warming would then accelerate, adding another 40 degrees over the following 500 million years. That extreme heat would exceed even the most resilient plants' tolerance, putting the extinction of vegetation about 1,870,000,000 years from now. The authors caution that predictions over such vast timescales carry impressive uncertainty.
The second scenario focuses on declining atmospheric CO₂. Geological and atmospheric processes could lower CO₂ from today's levels of over 400 parts per million to just above 30 parts per million within a billion years. That drop would deprive most plants of the carbon they need for photosynthesis. Even under the most favorable conditions, plant life would struggle to survive beyond 1.84 billion years. The study also suggests Earth's oceans could evaporate in about 1.5 billion years, while microbial life might persist underground for longer.
The carbon cycle moves CO₂ between the atmosphere and Earth's geological reservoirs. Weathering and carbonate formation remove carbon from the air, while volcanic and metamorphic processes return it. As the Sun brightens and the planet warms, changes in weathering can shift that balance. The biological threshold also varies: C3 and C4 plants use different photosynthetic pathways, with distinct CO₂ requirements and temperature tolerances. The decline of one group would not necessarily mean all photosynthetic life disappears at the same time.
Unlike the sudden mass extinctions of the past, the end of plant life is expected to unfold gradually as habitable conditions decline. The researchers stress that vegetation will not go extinct overnight; the process will take millions of years as the planet becomes less hospitable. Previous estimates placed the end of plant life much sooner. Some predicted a limit within 100 million years, while others put it at about a billion years. This model pushes the timeline much further, though its projections depend on interacting planetary and solar processes. These include solar brightening and atmospheric CO₂, as well as changes in weathering. Clouds and water availability also matter.
Estimates of Earth's future habitability can refer to different milestones. One is the loss of liquid surface water; another is the collapse of complex ecosystems. Plants could lose the ability to photosynthesize before all surface life disappears. Those are separate events. The Sun is expected to enter its red-giant phase more than five billion years from now, but conditions for surface life could become hostile well before then. Boise State University's educational material on the Sun's future also distinguishes its later stellar evolution from earlier changes that will affect Earth's environment.
For Spain and the rest of the world, these findings show the immense timescales involved in planetary change. Plant extinction is not an immediate concern, but the study examines the balance that sustains Earth's biosphere. Atmospheric CO₂ concentrations are already debated because of their role in climate change. The processes described in the study, but, operate on a scale far beyond human lifespans or policy planning. The research offers a long-term view of Earth's future and the eventual limits of life as we know it.
