Climate change is happening at an unprecedented rate, leaving forests behind in its wake. For decades, ecologists have been concerned that forest ecosystems will not be able to keep pace with this rapid warming, ultimately becoming unhealthy and unproductive.

In reality, tree populations in the Northern Hemisphere had adapted to colder and warmer periods over thousands of years before the current climate crisis. During Ice Ages, trees would migrate south to find warmer conditions as global temperatures cooled. However, when the climate warmed again, these same species would adapt by migrating northward to more suitable areas.

Mature trees are long-lived, but their populations cannot migrate quickly enough to keep up with today’s accelerated climate change. The study recently published in Science reveals that forests have a significant lag time of one to two centuries to shift tree populations in response to climate changes.

Lead researcher David Fastovich from Syracuse University’s Paleoclimate Dynamics Lab explains that this research aimed to map the timescales at which tree populations respond to climate change by examining pollen data from lake sediment cores spanning up to 600,000 years ago. The team used spectral analysis – a statistical technique common in fields like physics and engineering – to study long-term ecological data.

Spectral analysis allowed researchers to compare the relationship between tree populations and climate over various timescales, from decades to millennia. This method provided insights into how closely tree population migrations, tree mortality, and forest disturbances match climate changes over time.

The findings indicate that at timescales of years and decades, forests tend to change slowly. However, after about eight centuries, larger changes in the forest become more pronounced, tied to natural climate variability.

Fastovich emphasizes that this new technique can help us understand ecological processes on any timescale and how they are connected. It also highlights the need for nuanced, long-term management strategies to assist forests in adapting to climate change.

One such strategy is assisted migration – the practice of planting warmer-climate trees in traditionally colder locations to help woodlands adapt and flourish despite habitat warming from climate change. Fastovich notes that this approach will be crucial in helping cherished forests thrive in a rapidly changing world.

In conclusion, while forests have a natural lag time in responding to climate change, assisted migration and other human interventions can play a vital role in keeping these ecosystems healthy and productive for longer.

The tropical forests that cover vast swaths of our planet are facing an unprecedented threat: thunderstorms. These powerful convective storms have long been overlooked as a significant driver of tree mortality in these ecosystems, but new research suggests that they may be responsible for up to 60% of tree deaths in some regions. Led by Evan Gora, a forest ecologist at the Cary Institute of Ecosystem Studies, a team of scientists has reanalyzed data from previous studies on tropical forest carbon stocks and found that storms are at least as good as drought and temperature in explaining patterns of tree mortality and forest carbon storage.

“We were surprised to find that storms may be the largest single factor causing tree death in these forests,” said Gora. “They’re largely overlooked by research into carbon storage in the tropics, and our estimates suggest that they’re responsible for 30 to 60% of tree mortality in the past.”

These findings have significant implications for forest management practices and long-term conservation efforts. If scientists continue to make decisions about which species to plant or conserve based on an incorrect understanding of what’s actually killing these trees and which species are most vulnerable, those forests won’t reach their full potential.

The researchers note that storms and droughts can be mutually exclusive – the same forests can experience both high storm activity and drought stress. They found high convective storm activity across the southern Amazon, where water stress is also high and patterns of change are among the most extreme.

To overcome the challenges in detecting storms and tracking their highly localized damage, the researchers used a combination of a lightning location system, drone scouts, and on-the-ground experts to sample large areas of tropical forest frequently. With these tools, they were starting to quantify when, where, and why tropical trees are dying, and which species are most affected.

Understanding current and future threats to tropical forests is crucial to informing long-term conservation and restoration efforts. If we make decisions about which species to plant or conserve based on an incorrect understanding of what’s actually killing these trees and which species are most vulnerable, those forests won’t reach their full potential.

The collapse of tropical forests during Earth’s most catastrophic extinction event was the primary cause of the prolonged global warming that followed, according to new research.

The Permian-Triassic Mass Extinction – sometimes referred to as the “Great Dying,” happened around 252 million years ago, leading to the massive loss of marine species and significant declines in terrestrial plants and animals.

For decades, scientists have been unable to pinpoint why super-greenhouse conditions persisted for around five million years afterwards. Now a team of international researchers has gathered new data that supports the theory that the demise of tropical forests and their slow recovery limited carbon sequestration – a process where carbon dioxide is removed from the atmosphere and held in plants, soils, or minerals.

The researchers used a new type of analysis of fossil records as well as clues about past climate conditions found in certain rock formations to reconstruct maps of changes in plant productivity during the Permian-Triassic Mass Extinction. Their results show that vegetation loss during the event led to greatly reduced levels of carbon sequestration, resulting in a prolonged period with high levels of CO2.

The paper’s lead author, Dr. Zhen Xu from the University of Leeds, said: “The causes of such extreme warming during this event have been long discussed, as the level of warming is far beyond any other event.”

Critically, this is the only high-temperature event in Earth’s history where the tropical forest biosphere collapses, which drove our initial hypothesis. Now, after years of fieldwork, analysis, and simulations, we finally have the data that supports it.

The researchers believe their results reinforce the idea that thresholds or ‘tipping points’ exist in Earth’s climate-carbon system that, when reached, mean that warming can be amplified.

China is home to the most complete geological record of the Permian-Triassic mass Extinction and this work leverages an incredible archive of fossil data gathered over decades by three generations of Chinese geologists. The lead author Dr. Zhen Xu is the youngest of these and is continuing the work begun by Professor Hongfu Yin and Professor Jianxin Yu, who are also authors of the study.

Since 2016, Zhen and her colleagues have traveled throughout China from subtropical forests to deserts, visiting areas accessible only by boat or on horseback. Zhen came to the University of Leeds in 2020 to work with Professor Benjamin Mills on simulating the extinction event and assessing the climate impacts of the loss of tropical vegetation shown by the fossil record.

Their results confirm that the change in carbon sequestration suggested by the fossils is consistent with the amount of warming that occurred afterwards. Professor Mills added: “There is a warning here about the importance of Earth’s present-day tropical forests. If rapid warming causes them to collapse in a similar manner, then we should not expect our climate to cool to preindustrial levels even if we stop emitting CO2.”

Indeed, warming could continue to accelerate in this case even if we reach zero human emissions. We will have fundamentally changed the carbon cycle in a way that can take geological timescales to recover, which has happened in Earth’s past.

Reflecting on the study’s broader mission, Professor Hongfu Yin and Professor Jianxin Yu of the China University of Geosciences underscored the urgency of blending tradition with innovation: “Paleontology needs to embrace new techniques – from numerical modeling to interdisciplinary collaboration – to decode the past and safeguard the future,” explained Professor Yin.

Professor Yu added: “Let’s make sure our work transcends academia: it is a responsibility to all life on Earth, today and beyond. Earth’s story is still being written, and we all have a role in shaping its next chapter.”