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.
Let the Truth be known. If you read VB and like VB, please be a VB Supporter and Help us deliver the Truth to one and all.
Russian military hardware, spare parts for Indian military to be manufactured in India
New Delhi (PTI): Russia agreed to encourage joint manufacturing in India of military hardware and spare parts for maintenance of Russian-origin arms and defence equipment.
Ways to bolster overall bilateral defence cooperation figured prominently during summit talks between Prime Minister Narendra Modi and Russian President Vladimir Putin on Friday.
It has been a long-standing grievance of armed forces that the supply of critical spares and equipment from Russia takes a long time, affecting the maintenance of military systems procured from that country.
"Both sides agreed to encourage joint manufacturing in India of spare parts, components, aggregates and other products for maintenance of Russian origin arms and defence equipment under Make-in-India programme through transfer of technology," a joint statement said.
ALSO READ: India, Russia explore cooperation on small modular reactors, floating nuclear power plants
It said both sides also agreed to set up joint ventures for meeting the needs of the Indian armed forces as well as subsequent export to mutually friendly third countries.
The joint statement said the India-Russia defence partnership is being reoriented to take up joint co-development and co-production of advanced defence technology and systems.
In their meeting on Thursday, Defence Minister Rajnath Singh and his Russian counterpart Andrey Belousov resolved to expand bilateral defence cooperation.
In the meeting, the Indian side showed keen interest in procurement of additional batches of S-400 missile systems from Moscow to bolster its combat prowess.
In October 2018, India signed a USD 5 billion deal with Russia to buy five units of the S-400 air defence missile systems, notwithstanding a warning by the US that going ahead with the contract may invite US sanctions under the provisions of Countering America's Adversaries Through Sanctions Act (CAATSA).
Three squadrons have already been delivered.
The S-400 systems played a crucial role during Operation Sindoor. India may also look at procuring the S-500 missile systems from Russia.
In the Modi-Putin talks, the two sides also agreed to continue jointly developing systems of bilateral trade settlements through the use of national currencies.
Additionally, the two sides agreed to continue their consultations on enabling the interoperability of the national payment systems, financial messaging systems, as well as central bank digital currency platforms.
Modi and Putin appreciated the ongoing intensification of the joint work on a free trade agreement on goods between India and the Eurasian Economic Union, covering sectors of mutual interest, the joint statement said.
They also directed both sides to intensify efforts in negotiations on a mutually beneficial agreement on the promotion and protection of investment, it said.
India and Russia also welcomed steps to ensure long-term supply of fertilisers to India and discussed the potential establishment of joint ventures in this area.
