Plants could take millions of years to restabilize the Earth after climate change

(CN) — An international team of climate scientists warns that, judging from previous periods of global warming, it can take plants millions of years to get the planet’s climate regulation mechanisms back on track.

A new study from ETH Zurich, a research university in Switzerland, examined three major volcanic warming events in the planet’s history, each of which saw the global average surface temperature increase by several degrees Celsius due to massive, prolonged carbon emissions.

The international team of scientists from Switzerland, the United Kingdom, France and the United States examined isotopes in sediments from these ancient events alongside simulations in a computer model of Earth’s plant life before, during and after those events.

They found that how long the planet’s plant life takes to adapt to the massive carbon emissions, both in evolving to absorb the emitted carbon and in evolving to survive the increased temperatures, determines how long it takes for the climate to settle in a new equilibrium and how much warmer the new equilibrium will be.

Their simulations found that Earth’s plant life adapts in one of two main ways. In the first, the plants’ evolution lags behind and stifles their ability to mediate atmospheric carbon, but eventually catches up and returns the planet’s temperatures back to where they were before the warming event. In the second, the plants do not fully adapt, leaving the climate to stabilize at a warmer global average surface temperature.

In the third scenario, plant life fails to adapt and dies out almost entirely, then temperatures increase until silicate dust erosion can compensate for the lack of plants and allow plant life to slowly return.

That is what happened after two million years of eruptions formed the Siberian Traps, a large volcanic rock region in northern Russia, about 252 million years ago. It caused the Permian-Triassic mass extinction event, the largest mass dying in Earth’s history, and raised global temperatures by 5 to 10 degrees Celsius for the bulk of 200,000 years.

“The recovery of vegetation from the Siberian Traps event took several millions of years and during this time Earth’s carbon-climate regulation system would have been weak and inefficient, resulting in long-term climate warming,” Julian Rogger, lead author and PhD candidate at the Institute of Geophysics at ETH Zurich, explained in a press release.

Several of the study’s authors expressed strong worries about what their findings mean for the current climate crisis.

“Today, we find ourselves in a major global bioclimatic crisis,” Loïc Pellissier, Professor of Ecosystems and Landscape Evolution at ETH Zurich and WSL, commented in the press release. “Our study demonstrates the role of a functioning of vegetation to recover from abrupt climatic changes. We are currently releasing greenhouse [gasses] at a faster rate than any previous volcanic event. We are also the primary cause of global deforestation, which strongly reduces the ability of natural ecosystems to regulate the climate. This study, in my perspective, serves as [a] ‘wake-up call’ for the global community.”

Ben Mills, professor of earth system evolution at the University of Leeds’s School of Earth and Environment, echoed a similar sentiment.

“The events in our study took place millions of years ago and played out over hundreds of thousands of years. But they tell a cautionary tale for the present day,” Mills said. “Temperature-driven collapse of the world’s tropical forests has happened before and can happen again."

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