Today, human-driven climate change is happening at a pace 10 times faster than the Paleocene-Eocene Thermal Maximum (PETM), an ancient global warming event. With plants already struggling to keep up, the consequences of this rapid change may hinder their crucial role in carbon storage and climate regulation.
How Plants Regulate the Climate
Plants are key players in regulating the Earth’s climate through a process known as carbon sequestration. This involves absorbing carbon dioxide from the atmosphere during photosynthesis and storing it in their biomass, including leaves, wood, and roots. By doing this, plants help maintain balance in the Earth’s carbon cycle and play a vital role in mitigating climate change.
However, sudden or extreme climate shifts, like the one that occurred during the PETM, can disrupt this process. According to a study published in Nature Communications, the extreme global warming 56 million years ago caused many plant species to struggle, and their carbon absorption abilities were reduced. This ultimately contributed to the prolonged nature of the warming event, which lasted far longer than expected.
Vegetation Responses to the PETM
The PETM was an event of rapid global warming that increased carbon in the atmosphere and raised global temperatures by approximately 6°C over a short period. Research on this event reveals how vegetation responded to such rapid changes. By examining fossil pollen and plant traits, scientists reconstructed how vegetation across different regions shifted during the warming event.
In mid-latitude regions, such as the Bighorn Basin in Wyoming, the fossil record shows a shift toward smaller, more drought-resistant plants like palms and ferns. These species could better withstand the hotter conditions but had a reduced capacity to store carbon. In contrast, the high-latitude regions, like the Arctic, showed a boost in plant biomass as vegetation adapted to the warmer climate. Despite this, overall carbon sequestration decreased significantly for up to 100,000 years as ecosystems failed to recover quickly from the climate shock.
The Impact of Slow Adaptation
The ability of plants to adapt to new climates is crucial for maintaining their role in carbon sequestration. However, the PETM demonstrated that plant evolution and migration could not keep up with the speed of warming. According to researchers, plant species were unable to adjust to the changing climate fast enough, which contributed to the long-lasting disruption of carbon storage systems.
The research also highlights how vegetation that thrives in extreme conditions, like small, hardy palms and ferns, can persist, but these plants tend to be less efficient at storing carbon than their larger, more robust counterparts. This adaptation lag, caused by rapid warming, meant that the Earth’s carbon sequestration systems were significantly weakened for tens of thousands of years. This delayed recovery could be seen in the ongoing climate patterns today, where ecosystems face similar pressures from increasing temperatures.
Today’s climate crisis is unfolding at a rapid pace, with temperatures rising ten times faster than during the PETM. The study underscores the urgent need to understand how plants can adapt to such rapid environmental changes. If current warming trends continue, the carbon storage capabilities of modern vegetation could be at risk. This, in turn, could hinder efforts to slow down climate change and lead to a longer-lasting disruption of the global carbon cycle.