News
Trees ‘remember’ wetter times − never having known abundant rain could buffer today’s young forests against climate change
In a changing climate, trees exhibit “legacy effects” from past droughts or wet periods. Young trees, adapted to arid conditions, offer hope for future forest resilience amidst escalating climate challenges globally.
Alana Chin, Cal Poly Humboldt ; Janneke Hille Ris Lambers, Swiss Federal Institute of Technology Zurich, and Marcus Schaub, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
What does the future hold for forests in a warmer, drier world? Over the past 25 years, trees have been dying due to effects of climate change around the world. In Africa, Asia, North America, South America and Europe, drought stress amplified by heat is killing trees that have survived for centuries.
Old trees may have grown through entire millennia that were wetter than the past 20 years. We are scientists who study forest dynamics, plant ecology and plant physiology. In a recent study, we found that trees can remember times when water was plentiful and that this memory continues to shape their growth for many years after wet phases end.
This research makes us optimistic that young trees of today, which have never known 20th-century rainfall, have not shaped their structure around water abundance and thus may be better equipped to survive in a chronically dry world.
What if we water the forest?
This study built on nearly 20 years of forest research in response to early warning signs of forest loss in the 1990s in the dry Rhône River Valley of the Swiss Alps. At that time, scientists observed that Scots pine trees that had stood for around 100 years were declining and dying. They wondered whether drought or other climate factors were driving this loss.
To tackle this question, researchers at the Swiss Federal Institute for Forest, Snow and Landscape Research designed an ecological experiment. To understand the impacts of drought, they would irrigate a mature forest, doubling natural summertime rainfall, and then compare how these water-rich trees fared in comparison with those receiving only natural precipitation.
The Pfynwald experiment, launched in 2003, has shown that trees survived at higher rates in irrigated plots. After 17 years of irrigation, the team found that irrigation didn’t just help trees survive dry phases – it also increased their growth rates. https://www.youtube.com/embed/OA7A-xWhDeo?wmode=transparent&start=0 Tree physiologist Leonie Schönbeck conducts research at Pfynwald, a natural reserve in southern Switzerland, to learn how trees take up and store energy and use their reserves to recover from drought.
Legacy effects are forests’ memories
Trees experiencing drought alter their leaves, wood and roots in ways that prime them for continued dry conditions. Wood under drought might have smaller cells that are less vulnerable to future damage, and roots might increase relative to leaf area. These structural changes persist after the drought has passed and continue to influence the tree’s growth and ability to tolerate stress for many years.
Known as “legacy effects,” these lingering post-drought impacts represent an ecological memory of past climatic conditions at the tree and forest level. Knowing that trees hold a persistent memory of past dry phases, researchers wondered whether they might also show structural changes in response to past wet periods.
Eleven years after summertime irrigation started in Pfynwald, scientists stopped irrigating half of each plot in 2013 to address this question. The formerly irrigated trees, which at this point were about 120 years old, had experienced a lasting period of irrigation – but now those times of plenty were over.
Would the trees remember? A decade later, we found out.
Trees, trains and particle accelerators
On an early March morning in 2023, two of us (Alana Chin and Marcus Schaub) met at Pfynwald to collect very fresh leaf and twig samples so that we and colleagues could look inside to search for signs of lasting effects of past water richness.
At the site, we climbed canopy access towers to collect newly grown treetop leaves and twigs from control trees that had never been irrigated; trees that had been irrigated every summer since 2003; and formerly irrigated trees that had not received irrigation water since 2013.
We took our samples to the Swiss Light Source, an intensely powerful synchrotron – a type of particle accelerator that produces the world’s most intense beams of light. This facility is the home of the TOMCAT, an extremely high-resolution X-ray that allowed us to look inside our leaves and twigs without disturbing their structure.
Scanning our samples took all night, but when we stumbled out of the building, we had images capturing every cell in exquisite detail.
The memory of water
We found that the new leaves of once-irrigated trees were different from both continually watered trees and never-watered control trees. Leaves carry out photosynthesis that fuels a tree’s survival and growth. Inside them, we could see the legacy of past water abundance, written in the size, shape and arrangement of cells.
Reading this cellular signature, we observed that, at the expense of structures promoting productivity, formerly irrigated trees showed every sign of chronic water stress – even more so than never-irrigated trees. In their anatomy, we saw why these trees that had it easy for 11 wet years were now growing slowly.
Every cell in a leaf comes with a trade-off. Trees must balance investments in rapid photosynthesis with others that promote leaf survival. Rather than building the cells used to harvest sunlight and ship sugar to the rest of the tree, leaves on the trees that had been irrigated showed every indication of drought stress we could think to measure.
After receiving extra water for an 11-year stretch and then losing it, the trees were producing new, tiny leaves that invested mostly in their own survival. The leaves were structured to protect themselves from insects and drought and to store water reserves. Compared with leaves on trees that had never known irrigation, these looked as though they were in the middle of the drought of the century.
While this memory of water might seem negative, it likely once helped trees “learn” from past conditions to survive in variable environments. The formerly irrigated trees did not know that humans had played a trick on them. Like trees experiencing climate change, they had no way of knowing that the water was not coming back.
When trees experience a drought event, recovery can mean reaching a “new normal” state, in which they are prepared to survive the next drought, with smaller, less vulnerable cells and increased energy reserves to ‘save up’ for future dry periods. They may have deeper roots or a smaller pool of leaves to support, helping them prepare for an unstable environment.
We wanted to know whether the same was true of trees that had experienced water abundance. Were they waiting in distress for the water to return?
Hard times may make tough trees
In some temperate forests, like the ones we studied in Switzerland, old trees once knew levels of water abundance that now are gone, thanks to climate change. That past abundance may have locked into place structural and epigenetic changes in the trees that are mismatched to today’s drier world. If this is true, then some of today’s devastating global tree mortality events may be, in part, due to the legacy effects of past water abundance.
In most of the world’s temperate forests, however, the current cohort of young forest trees – those sprouting in the past 15 to 20 years – has managed to establish itself under conditions that once would have been considered chronic drought. Those young trees, which have survived an endless dry period, will form the forests of the future.
In all, our observations in Pfynwald have provided us some room for hope that young trees currently taking their place in many forests worldwide may be better prepared to cope with the world as humans have shaped it. Climate shifts in recent decades have primed them for hard times, without the lingering memory of water.
Alana Chin, Assistant Professor of Plant Physiology, Cal Poly Humboldt ; Janneke Hille Ris Lambers, Professor of Environmental Systems Science, Swiss Federal Institute of Technology Zurich, and Marcus Schaub, Group Leader, Forest Dynamics and Ecophysiology, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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News
How healthy is Sodastream?
The SodaStream Sparkling Water Maker is a device that forces carbon dioxide (CO2) gas (stored under pressure in a cylinder) into water, making it sparkling (fizzy)
Sodastream machines have been gaining popularity in recent years as an alternative to store-bought soft drinks. Not only are they more environmentally friendly, but they also offer several health benefits compared to traditional sodas.
Reduced Sugar Intake
One of the most significant health benefits of using a Sodastream machine is reducing sugar intake. Traditional sodas are loaded with sugar, and excessive sugar intake can lead to weight gain, obesity, and other health problems such as Type 2 diabetes. With a Sodastream machine, you can control the amount of sugar you add to your drink, allowing you to enjoy a refreshing beverage without the harmful effects of excessive sugar consumption.
No Artificial Sweeteners
Many store-bought soft drinks contain artificial sweeteners, which can have negative health effects such as headaches and digestive problems. Sodastream machines, on the other hand, allow you to use natural sweeteners such as fruit extracts, honey or agave nectar, giving you a healthier and more natural alternative.
No Preservatives
Another advantage of using a Sodastream machine is that you can avoid preservatives commonly found in store-bought soft drinks. Preservatives such as sodium benzoate and potassium sorbate have been linked to health problems such as cancer and allergies. By making your own drinks, you can avoid these harmful additives and enjoy a healthier, preservative-free beverage.
Eco-Friendly
In addition to the health benefits, using a Sodastream machine is also environmentally friendly. Traditional soft drinks are packaged in plastic bottles or cans, which contribute to environmental pollution. With a Sodastream machine, you can reuse the same bottle multiple times, reducing waste and helping to reduce your carbon footprint.
Variety
Finally, Sodastream machines offer a wide variety of flavors and options, allowing you to customize your drink to your liking. You can mix and match different flavors or create your own unique blends, giving you a healthier and more enjoyable alternative to traditional sodas.
In conclusion, Sodastream machines offer several health benefits compared to traditional store-bought soft drinks. By reducing sugar intake, avoiding artificial sweeteners and preservatives, and being eco-friendly, they offer a healthier and more sustainable alternative to traditional soft drinks. Moreover, with a wide variety of flavors and options, you can customize your drink to your liking, making it a fun and enjoyable way to stay healthy.
Consumer Corner
Behind the Product: What Sustainability Looks Like in Beauty Development
Beauty Development: Shoppers want to know what ingredients are used, how items are packaged and whether the production process includes thoughtful choices. Beauty brands are taking note, and sustainability is increasingly shaping decisions across sourcing, packaging, production, shipping, storage and replenishment.
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(Feature Impact) Shoppers are paying closer attention to the products they bring into their homes. They want to know what ingredients are used, how items are packaged and whether the production process includes thoughtful choices. Beauty brands are taking note, and sustainability is increasingly shaping decisions across sourcing, packaging, production, shipping, storage and replenishment.
Responsible product lines rarely come from sweeping change. They are built through smaller, connected choices made throughout development. Packaging, ingredient sourcing and production planning influence how a product performs, how much waste it creates and how sustainably products can be produced.
Consider this beauty sustainability information from Laura Badcock, Chief Operating Officer of NourishUs Naturals.
Why packaging matters beyond appearance
“Packaging is often the first thing shoppers notice,” Badcock said. “It can shape how someone feels about a product before they ever try what’s inside.”
A package should look appealing, though appearance is only part of the equation. It also needs to protect the product, travel safely, store well and hold up through regular use. Once the product is finished, the packaging should allow easy recycling, refilling or responsible disposal.
There is no single packaging option that works best for every beauty product. A lightweight container may reduce shipping weight. A refillable option may stay in use longer. A recyclable material may work well in one area but create challenges in another if local recycling systems cannot process it. Even packaging that appears sustainable can create problems in practice if it leaks, breaks or requires excess shipping materials.
Why ingredient sourcing matters
“Ingredient lists have become an important part of how people evaluate beauty products,” Badcock said. “Shoppers often look for familiar oils, butters, botanical extracts and information about how ingredients were sourced, which plays a major role in the environmental impact.”
A product’s environmental footprint is influenced by many factors, including shipping distance, processing methods, storage conditions and supplier practices.
These factors can also affect product consistency and ingredient availability over time. Beauty brands working with wholesale skin care suppliers or private label manufacturers often need to balance ingredient goals with sourcing reliability and production needs.
How better planning can lead to less waste
“Packaging and ingredients are usually the first things people associate with sustainability, but how much product gets made, stored and discarded matters, too,” Badcock said.
Overproduction is one of the biggest hidden sources of waste in beauty and personal care. Products that sit too long in storage may eventually expire or remain unsold. Excess inventory can also create additional packaging waste, warehousing needs and disposal costs.
Smaller batch sizes give producers more room to adjust as trends or demand shift, and producing closer to expected sales windows helps reduce long storage periods and unnecessary waste. Testing new products in smaller volumes and restocking based on actual demand makes overproduction less likely.
How sustainable beauty choices are connected
Packaging, ingredient sourcing and production planning are closely connected throughout development.
“A packaging choice can affect shipping weight, storage needs and whether a package can be refilled,” Badcock said. “Ingredient choices can influence sourcing timelines and how products need to be stored. Production planning affects how much material gets used and how much product could eventually go unsold.”
Beauty shoppers want more transparency around sustainability claims
Sustainability claims carry less weight when those claims aren’t explained in practice.
This shift is pushing many beauty brands to focus more heavily on traceability, supplier relationships and clearer product information. Transparency is becoming part of the customer experience itself.
More responsible product lines are built over time
Responsible beauty products come together through ongoing choices around packaging, sourcing, production and inventory planning. For shoppers, those choices influence the products they bring into their homes.
“The brands that build sustainability into early decisions tend to have the easiest time maintaining it later,” Badcock said. “Once supplier relationships, packaging formats and production routines are in place, small adjustments are far easier than major changes. Treating sustainability as part of product development from the beginning, rather than something to fix later, is what makes it work in practice.”
To find more information on the intersection of beauty and sustainability, visitNourishUsNaturals.com.
Photo courtesy of Shutterstock
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Automotive
EPA removal of vehicle emissions limits won’t stop the shift to electric vehicles, but will make it harder, slower and more expensive
The EPA’s move to rescind the 2009 “endangerment finding” and roll back vehicle emissions limits won’t stop the shift to electric vehicles—but it will slow adoption, raise costs, and increase climate and public health harms.
Alan Jenn, University of California, Davis
The U.S. government is in full retreat from its efforts to make vehicles more fuel-efficient, which it had been prioritizing, along with state governments, since the 1970s.
The latest move came on Feb. 12, 2026, when President Donald Trump and the Environmental Protection Agency issued a new rule rescinding the landmark “endangerment finding,” and reversing various emissions limits on cars and trucks. The 2009 finding stated that greenhouse gases pose a threat to public health and welfare. If the new rule stands up in court and is not overruled by Congress, it would undo a key part of the long-standing effort to limit greenhouse gas emissions from vehicles.
As a scholar of how vehicle emissions contribute to climate change, I know that the science behind the endangerment finding hasn’t changed. If anything, the evidence has grown that greenhouse gas emissions are warming the planet and threatening people’s health and safety. Heat waves, flooding, sea-level rise and wildfires have only worsened in the decade and a half since the EPA’s ruling.
Regulations over the years have cut emissions from power generation, leaving transportation as the largest source of greenhouse gas emissions in the U.S.
The scientific community agrees that vehicle emissions are harmful and should be regulated. The public also agrees, and has indicated strong preferences for cars that pollute less, including both more efficient gas-burning vehicles and electric-powered ones. Consumers have also been drawn to electric vehicles thanks to other benefits such as performance, operation cost and innovative technologies.
That is why I believe the EPA’s move will not stop the public and commercial transition to electric vehicles, but it will make that shift harder, slower and more expensive for everyone.
Putting carmakers in a bind
The most recent EPA rule about vehicle emissions was finalized in 2024. It set emissions limits that can realistically only be met by a large-scale shift to electric vehicles.
Over the past decade and a half, automakers have been building up their capability to produce electric vehicles to meet these fleet requirements, and a combination of regulations such as California’s zero-emission-vehicle requirements have worked together to ensure customers can get their hands on EVs. The zero-emission-vehicle rules require automakers to produce EVs for the California market, which in turn make it easier for the companies to meet their efficiency and emissions targets from the federal government. These collectively pressure automakers to provide a steady supply of electric vehicles to consumers.
The new EPA move would undo the 2024 EPA vehicle-emissions rule and other federal regulations that also limit emissions from vehicles, such as the heavy-duty vehicle emissions rule.
The possibility of a regulatory reversal puts automakers into a state of uncertainty. Legal challenges to the EPA’s shift are all but guaranteed, and the court process could take years.
For companies making decade-long investment decisions, regulatory stability matters more than short-term politics. Disrupting that stability undermines business planning, erodes investor confidence and sends conflicting signals to consumers and suppliers alike.
A slower roll
The Trump administration has taken other steps to make electric vehicles less attractive to carmakers and consumers.
The White House has already suspended key provisions of the Inflation Reduction Act that provided tax credits for purchasing EVs and halted a US$5 billion investment in a nationwide network of charging stations. And Congress has retracted the federal waiver that allowed California to set its own, stricter emissions limits. In combination, these policies make it hard to buy and drive electric vehicles: Fewer, or no, financial incentives for consumers make the purchases more expensive, and fewer charging stations make travel planning more challenging.
Overturning the EPA’s 2009 endangerment finding would remove the legal basis for regulating climate pollution from vehicles altogether.
But U.S. consumer interest in electric vehicles has been growing, and automakers have already made massive investments to produce electric vehicles and their associated components in the U.S. – such as Hyundai’s EV factory in Georgia and Volkswagen’s Battery Engineering Lab in Tennessee.
Global markets, especially in Europe and China, are also moving decisively toward electrifying large proportions of the vehicles on the road. This move is helped in no small part due to aggressive regulation by their respective governments. The results speak for themselves: Sales of EVs in both the European Union and China have been growing rapidly.
But the pace of change matters. A slower rollout of clean vehicles means more cumulative emissions, more climate damage and more harm to public health.
The EPA’s move seeks to slow the shift to electric vehicles, removing incentives and raising costs – even though the market has shown that cleaner vehicles are viable, the public has shown interest, and the science has never been clearer. But even such a major policy change can’t stop the momentum of those trends.
This is an updated version of an article originally published Aug. 5, 2025.
Alan Jenn, Associate Professor of Civil and Environmental Engineering, University of California, Davis
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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