Some tree leaves will fall 3-6 days in advance by end of century due to climate change: Study
Berlin: A large-scale study of European trees suggests that the leaves of trees between the tropics and the polar regions of the Earth will start to fall in advance by three to six days by the end of the 21st century rather than lengthening by one to three weeks as current models have predicted.
The scientists, including those from the University of Munich (LMU) in Germany, said earlier studies had predicted that the shedding of leaves from these temperate trees will get later under the ongoing climate crisis.
They said early observations also supported this idea since warming caused leaves to stay on the trees later over recent decades, driving increased growing season length that could help to slow the rate of climate change.
However, the current study, published in the journal Science, showed that this trend might be reversed as increasing photosynthetic productivity begins to drive earlier autumn leaf fall or senescence.
According to the researchers, the results build on growing evidence that plant growth is limited by the ability of tree tissues to use and store carbon.
While changes in the growing-season lengths of temperate trees greatly affect global carbon balance, they said future growing-season trajectories remain highly uncertain since the environmental drivers of autumn leaf senescence are poorly understood.
Autumn leaf-shedding at the end of the growing season in temperate regions is an adaptation to stressors, such as freezing temperatures, the scientists explained.
While a common assumption is that alleviating a warmer climate could allow leaves to persist longer and consume more atmospheric carbon, the researchers said the role of photosynthesis in governing the timing of leaf senescence has not been widely tested in trees.
In the current study, the scientists used long-term observations from dominant Central European tree species from 1948 to 2015, and experiments designed to modify carbon uptake by trees, to evaluate related impacts on senescence.
"Accounting for this effect improved the accuracy of senescence predictions by 27 to 42 percent and reversed future predictions from a previously expected 2- to 3-week delay over the rest of the century to an advance of three to six days," the scientists wrote in the study.
The data revealed that increased growing-season productivity in spring and summer due to elevated carbon dioxide, temperature, or light levels can lead to earlier -- not later -- leaf senescence.
This is likely because roots and wood cease to use or store leaf-captured carbon at a point, making leaves costly to keep, the study noted.
The model built by the researchers forecasted the possibility of slight advances, no delays, in autumn leaf-dropping dates over the rest of the century.
According to the scientists, the results "substantially lower our expectations of the extent to which longer growing seasons will increase seasonal carbon uptake in forests".
However, they said the universality of this pattern in other forest types remains unknown.
The researchers believe it is important to implement such growing-season length constraints in other models that do not consider these dynamics.
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London, Nov 22: A bomb disposal squad deployed as a “precaution” to the South Terminal of Gatwick Airport concluded an investigation into a "security incident" on Friday after making a “suspect package” safe.
The South Terminal of Gatwick Airport, the UK's second busiest airport after Heathrow, which was briefly shut owing to the incident reopened following the incident.
The Gatwick is around 45 km south of London.
Two people detained during the enquiries have since been allowed to continue their journey as the airport was opened.
“Police have concluded their investigation into a report of a suspect package at Gatwick Airport. Officers from the EOD (Explosive Ordnance Disposal) team made the package safe, and the airport has been handed back to its operator,” Sussex Police said in an updated statement.
“Two people detained while enquiries were ongoing have subsequently been allowed to continue their journeys. There will remain an increased police presence in the area to assist with passengers accessing the South Terminal for onward travel,” the statement added.
Earlier on Friday, the incident caused severe disruption at the busy airport’s South Terminal, while the North Terminal of Gatwick Airport remained unaffected.
“Police were called to the South Terminal at Gatwick Airport at 8.20 am on Friday (November 22) following the discovery of a suspected prohibited item in luggage,” a Sussex Police statement said.
“To ensure the safety of the public, staff and other airport users, a security cordon has been put in place whilst the matter is dealt with. As a precaution, an EOD (Explosive Ordnance Disposal) team is being deployed to the airport. This is causing significant disruption and some roads around the South Terminal have been closed. We’d advise the public to avoid the area where possible,” it said.
Footage on social media taken outside the airport showed crowds of frustrated travellers being moved away from the terminal building.
Gatwick said it was working hard to resolve the issue.
“A large part of the South Terminal has been evacuated as a precaution while we continue to investigate a security incident," the airport said in a social media post.
“Passengers will not be able to enter the South Terminal while this is ongoing. The safety and security of our passengers and staff remain our top priority. We are working hard to resolve the issue as quickly as possible.”
Train and bus services that serve the airport were also impacted while the police carried out their inquiries.
In an unrelated incident in south London on Friday morning, the US Embassy area in Nine Elms by the River Thames was the scene of a controlled explosion by Scotland Yard dealing with what they believe may have been a “hoax device”.
“We can confirm the 'loud bang' reported in the area a short time ago was a controlled explosion carried out by officers,” the Metropolitan Police said in a post on X.
“Initial indications are that the item was a hoax device. An investigation will now follow. Some cordons will remain in place for the time being but the majority of the police response will now be stood down,” it added.
