New climate modeling suggests Earth's plant life could remain viable for nearly 1.8 billion years more than many earlier estimates predicted. The research points to a surprisingly resilient future for photosynthesis, even as the Sun gradually becomes brighter.
A longer biological horizon
As the Sun ages, its energy output slowly rises, adding pressure to Earth's climate over immense timescales. That warming, combined with changes in atmospheric carbon dioxide, creates two competing challenges for plants: too much heat or too little CO2.
To explore that balance, researchers Jacob Haqq-Misra and Eric Wolf used a three-dimensional climate model that captures clouds, rainfall, ice, and regional temperature shifts more realistically than older approaches. Their results suggest the planet's vegetative biosphere may last between 1.35 billion and 1.86 billion years from now, depending on how weathering and carbon levels evolve.
Two future pathways
In one scenario, rock weathering stays relatively weak, leaving more carbon dioxide in the air but allowing global temperatures to climb. In that case, most land plants would likely exceed their heat tolerance around 1.68 billion years from now, while the hardiest species could persist until roughly 1.87 billion years.
In the opposite scenario, stronger weathering draws more CO2 out of the atmosphere. That helps limit warming, but it also removes the carbon plants need for photosynthesis. Under those conditions, the study suggests a major decline in the plant biosphere could begin around 1.35 billion years from now.
The most adaptable organisms may last the longest. CAM plants such as cacti and agave, along with some aquatic plants and algae, can use carbon sources more efficiently than many other species. That flexibility could extend the reach of photosynthetic life deep into Earth's future.
The findings also matter beyond our planet. If photosynthesis can persist for so long here, then older worlds orbiting aging stars may still host detectable life even when they no longer look ideal at first glance. The study was published in the Journal of Geophysical Research: Atmospheres.
It is a reminder that life can adapt across extraordinary timescales, and future astronomy may need to look for vitality in places once thought to be past their prime.
