The Earth
No, autumn leaves are not changing color later because of climate change
“Have scientists observed any changes in the timing or intensity of leaf color changes?”
Fall foliage on the Danforth Campus of Washington University in St. Louis.
It’s that time of year again. The days are getting shorter, and the nights are cooling down. But when will the natural fireworks display of autumn leaves actually begin this year?
Many people believe that climate change is pushing back the start of fall leaf color to later in the year. The general thinking is that the warmer conditions anticipated under climate change will mean that trees can “hang on” to their green, energy-producing leaves longer. But scientists do not actually see this happening across North American forests, according to an expert at Washington University in St. Louis.
“Warmer temperatures in September and October reduce anthocyanin production in leaves, which could mean that fall colors would become less brilliantly red or purple,” said Susanne S. Renner, honorary professor of biology in Arts & Sciences. “This effect is well documented in certain species, such as sugar maple, where experimental cooling of branches increases anthocyanin concentration and color brilliance. If the first frost comes later than it used to, the brilliant foliage will appear later than it used to.
“However, other factors counteract this. Most important is that trees drop their leaves earlier if they have had a very productive spring and summer. This overrides any delaying effects of a warm fall.
“The end result is that leaves still start to die after about the same amount of time on the tree as they have in years and even decades past,” she said.
In fact, under some scenarios we might even see leaves turning red and yellow earlier. Renner co-authored a 2020 study in the journal Science that showed that increased growing-season productivity drives earlier autumn leaf senescence — the process through which plants break down and reabsorb key nutrients that had been deployed in leaves — in temperate trees.
“If climate warming continues unabated, the situation is likely to change after about 2040, with senescence then starting earlier than it does now,” Renner said.
Here, Renner answers a few additional questions related to autumn leaf color change.
How do temperature and moisture conditions affect leaf color?
Yellow color in fall leaves is due to the retention of carotenoid pigments (xanthophylls) in senescing chloroplasts. Red and purplish color is due to the accumulation of anthocyanins in vacuoles, starting around September.
Rain does not affect these basic processes. Cold temperatures, however, enhance anthocyanin production, as shown experimentally in sugar maple. One can observe this in the sugar maple trees along St. Louis streets, which start turning colors at the very top, where the microclimate is coldest.
How might climate change alter color dynamics?
Because climate warming has resulted in warmer falls, in Canada and North America we are seeing less brilliant fall colors. Color brilliance is hard to quantify, but the effect has been experimentally demonstrated in sugar maple trees.
An interesting confounding factor is cleaner air. Thus, in Europe, atmospheric brightening due to cleaner air since 1983 has led to higher plant photosynthesis in the spring and summer — and earlier leaf senescence (compared with 1950-1982). These data, however, concern the breakdown of chlorophyll, not the production of red or yellow colors.
Will all kinds of trees respond in the same ways?
Absolutely not. Experimental work is revealing great species-specific differences. For example, trees that have nitrogen-fixing symbionts never turn red or yellow. Both pigments help protect leaves against damage from sunlight that is no longer usable for photosynthesis because of the massive degradation of chloroplast proteins in aging leaves. Trees with steady access to nitrogen may not bother with costly anthocyanin, but instead simply drop their leaves while still relatively green.
Are scientists already seeing changes to the timing or intensity of leaf color changes?
Warmer falls reduce the brilliance of red and yellow leaf colors, but brilliance is hard to quantify in long time series for many species. Also, many species simply do not turn red or yellow.
We have a paper under review that analyzes satellite data on “greenness” in Northern Hemisphere forests. We found that across a large majority of forest areas, higher spring and summer temperatures have led to an earlier (!!!) senescence by, on average, about 1.5 days per degree Celsius. Senescence here refers to degradation of chlorophyll or greenness.
Where in the world are autumn leaves most likely to be affected by climate change?
Species that change leaf color to red or yellow are much more frequent in North America than in Europe. With continued climate warming and lack of frost nights in October, colors will be less brilliant, but the onset or dates of color change will not change much because of the counteracting factors that I mentioned earlier. In the more distant future (after about 2040), and with unmitigated climate change, leaf senescence in Northern Hemisphere trees and shrubs will occur ever earlier.
Source: Washington University in St. Louis
- Mysterious Lights Over Oregon: Pilots Report Unusual Aerial Phenomena
This past weekend, the skies of Oregon became the backdrop for an extraordinary event that has both puzzled and dazzled observers. At least four commercial pilots reported encountering unexplained bright lights displaying incredible speeds and erratic movements, renewing interest and debate about aerial phenomena. The Encounter Details The first report came from a pilot operating… Read more: Mysterious Lights Over Oregon: Pilots Report Unusual Aerial Phenomena - NEOWISE, the NASA mission that cataloged objects around Earth for over a decade, has come to an end
Toshi Hirabayashi, Georgia Institute of Technology and Yaeji Kim, University of Maryland The NASA project NEOWISE, which has given astronomers a detailed view of near-Earth objects – some of which could strike the Earth – ended its mission and burned on reentering the atmosphere after over a decade. On a clear night, the sky is… Read more: NEOWISE, the NASA mission that cataloged objects around Earth for over a decade, has come to an end - Mysterious Drones Over New Jersey: A Deep Dive into the Sky’s Intrigue
In recent weeks, New Jersey has found itself at the center of a perplexing enigma—mysterious drones hovering in the night sky over various towns, stirring intrigue and concern among locals and officials alike. Reports of these unidentified flying objects (UFOs) have raised questions regarding their origins, purposes, and safety implications, prompting both state and federal… Read more: Mysterious Drones Over New Jersey: A Deep Dive into the Sky’s Intrigue - UFOs: how astronomers are searching the sky for alien probes near Earth
Beatriz Villarroel, Stockholm University There has been increased interest in unidentified flying objects (UFOs) ever since the Pentagon’s 2021 report revealed what appears to be anomalous objects in US airspace, dubbed unidentified aerial phenomena (UAP). Fast forward to 2023, and Nasa has already formed a panel to investigate the reports and appointed a director for… Read more: UFOs: how astronomers are searching the sky for alien probes near Earth - A Milestone in Space: Artemis Accords Welcome Panama and Austria as 50th Signatories
On December 11, 2024, Austria and Panama became the 49th and 50th nations to sign the Artemis Accords, emphasizing peaceful, cooperative space exploration.
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The Bridge
3 innovative ways to help countries hit by climate disasters, beyond a loss and damage fund
Erin Coughlan de Perez, Tufts University
These days, it’s hard to escape news stories discussing how climate change is contributing to extreme weather disasters, including the recent U.S. hurricanes. Aid agencies are increasingly worried about the widespread damage.
A growing question as these disasters worsen in a warming world is how to pay for recoveries, particularly in poorer countries that have contributed the least to climate change.
I am a climate scientist who researches disasters, and I work with disaster managers on solutions to deal with the increasing risk of extreme events. The usual sources of disaster aid funding haven’t come close to meeting the need in hard-hit countries in recent years. So, groups are developing new ways to meet the need more effectively. In some cases, they are getting aid to countries before the damage occurs.
Disaster aid funds aren’t meeting growing need
Countries have a few ways that they typically send money and aid to other countries that need help when disasters hit. They can send direct government-to-government aid, contribute to aid coordinated by the United Nations, or support disaster response efforts by groups like the International Red Cross and Red Crescent Movement.
However, the support from these systems is almost never enough.
In 2023, the amount of humanitarian funding through the U.N. was about US$22 billion. The U.N. Office for the Coordination of Humanitarian Affairs estimated that countries hit hard by disasters actually needed about $57 billion in U.N. humanitarian aid. This does not even include the costs borne directly by disaster-affected people and their governments.
https://datawrapper.dwcdn.net/LO7Uw/1
To help address damages specifically from climate change, the global community agreed at the U.N. climate conference in 2022 to create a new method – a Loss and Damage Fund. Loss and damage is generally defined as consequences of climate change that go beyond what people are able to adapt to.
The goal of the fund is for countries that historically have done the most to cause climate change to provide funding to other countries that did little to cause it yet are experiencing increasing climate-related disasters.
https://datawrapper.dwcdn.net/S1jUD/1
So far, however, the Loss and Damage Fund is tiny compared to the cost of climate-related disasters. As of late September 2024, total pledges to the Loss and Damage Fund were about US$700 million. According to one estimate, the costs directly attributable to climate change, including loss of life, are over $100 billion per year.
One goal of the 2024 U.N. climate conference, underway Nov. 11-22 in Azerbaijan, is to increase those contributions.
Sending aid before the disasters hit
In response to these growing needs, the disaster management community is getting creative about how it helps countries finance disaster risk reduction and response.
Traditionally, humanitarian funding arrives after a disaster happens, when photos and videos of the horrible event encourage governments to contribute financial support and a needs assessment has been completed.
However, with today’s technology, it’s possible to forecast many climate-related disasters before they happen, and there is no reason for the humanitarian system to wait to respond until after the disaster happens.
A global network of aid groups and researchers I work with has been developing anticipatory action systems designed to make funding available to countries when an extreme event is forecast but before the disaster hits.
This can allow countries to provide cash for people to use for evacuation when a flood is forecast, open extra medical services when a heat wave is expected, or distribute drought-tolerant seeds when a drought is forecast, for example.
Insurance that pays out early to avoid harm
Groups are also developing novel forms of insurance that can provide predictable finance for these changing catastrophes.
Traditional insurance can be expensive and slow to assess individual claims. One solution is “index insurance” that pays out based on drought information without needing to wait to assess the actual losses.
African nations created an anticipatory drought insurance product that can pay out when the drought starts happening, without waiting for the end of the season to come and the crops to fail. This could, in theory, allow farmers to replant with a drought-resilient crop in time to avoid a failed harvest.
Without insurance, disaster-affected people usually bear the costs of disaster. Therefore, experts recommend insurance as a critical part of an overall strategy for climate change adaptation.
Boosting social protection systems
Another promising area of innovation is the design of social services that can scale up when needed for extreme weather events.
These are called climate-smart social protection systems. For example, existing programs that provide food for low-income families can be scaled up during and after a drought to ensure that people have sufficient and nutritious food during the climate shock.
This requires government coordination among the variety of social services offered, and it offers promise to support vulnerable communities in the face of the rising number of extreme weather events.
Future of the Loss and Damage Fund
To complement these innovative disaster risk finance mechanisms, aid from other countries is crucial, and the Loss and Damage Fund is a key part of that.
There are still many areas of debate around the U.N.’s Loss and Damage Fund and what counts as true financial support. There have been discussions over whether investing in a country’s resilience to future disasters counts, whether existing financial systems should be used to channel finance to countries in need, and what damages are truly beyond the limits to adaptation and qualify.
The new Loss and Damage Fund is only of a part of a mosaic of initiatives that is seeking to address climate disasters.
These novel mechanisms to finance disaster risk are exciting, but they ultimately need to be created in conjunction with investments in adaptation and resilience so that extreme weather events cause less damage when they happen. Communities will need to plant different crops, build flood drainage systems and live in adaptive buildings. Managing climate risk requires a variety of innovative solutions before, during and after disaster events.
Erin Coughlan de Perez, Professor of Climate Risk Management, Tufts University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Science
How Buildings Contribute to Urban Heating during Heat Waves
Urban Heating: Researchers developed a model to analyze building heat emissions during heat waves, demonstrating a 20% increase in waste heat discharge significantly affecting urban microclimates, particularly in Los Angeles.
A bottom-up approach quantifies the contributions of human-caused heating from building energy use during extreme heat events.
The Science
Previous research has found that heat waves and urban heat island effects reinforce each other’s effects. These heat islands are concentrations of buildings, paved areas, and other surfaces that absorb and retain heat. Emissions of heat from buildings are an important part of this heat island effect. Researchers therefore need to understand the interplay of urban microclimates and these building heat emissions. New research developed a method for modeling urban building energy and associated human-caused heat during city-wide heat waves. The researchers used the method to examine the variation over time and space in emissions of waste heat from buildings in Los Angeles. The study incorporated building type, urban microclimate, and large-scale climate conditions.
The Impact
The method provides a high-resolution representation of how buildings contribute to heat islands during heat waves. It details both the magnitude and distribution of these heating effects. The simulation indicates that heat dispersing from buildings to the urban environment increases by as much as 20 percent during a heat wave. Most of this heat is waste heat from air conditioning. The study’s results will serve as a fundamental step in continued investigations of the feedback between changes in building waste heat and urban microclimates during extreme heat events.
Summary
The world is experiencing more frequent and longer-duration heat waves. These heat waves are a serious threat to human health and the stability of electrical grids. Previous studies have identified positive feedbacks between heat waves and urban heat island effects. Heat discharges from buildings and associated energy use have significant effect on the urban environment, and researchers therefore need to understand the interactive effects of urban microclimate and building heat emissions on the urban energy balance. In this study, scientists developed a coupled-simulation approach to quantify these effects, mapping urban environmental data generated by the mesoscale Weather Research and Forecasting (WRF) model, coupled to the Urban Canopy Model (UCM), to simulate urban building energy flows. The scientists conducted a case study in Los Angeles, California, during a five-day heat wave event in September 2009.
Urban Heating
The researchers analyzed the surge in city-scale building heat emission and energy use during the extreme heat event. They first simulated the urban microclimate at high resolution (500 by 500 meters) using WRF-UCM. Next, they generated grid-level building heat emission profiles and aggregated them using prototype building energy models informed by spatially disaggregated urban land use and urban building density data. They analyzed the spatial patterns of anthropogenic heat discharge from the building sector. They also assessed the quantitative relationship with weather conditions and urban land-use dynamics at the grid level. The simulation results indicate that during a heat wave, a rise in building energy use follows, and the associated discharge of anthropogenic waste heat from the buildings to the environment increases by as much as 20 percent on average, varying significantly, both in time and space. Notably, air-conditioning use within buildings intensifies, and resulting waste heat discharges outside of the buildings contribute most (86.5 percent) of the total waste heat transferred to the surrounding urban environment. The study also found that the waste heat discharge in inland, dense urban districts is more sensitive to extreme events than it is in coastal or suburban areas. The generated anthropogenic heat profiles can be used in urban microclimate models to provide a more accurate estimation of urban air temperature rises during heat waves.
Funding
This research was supported by the Department of Energy Office of Science as part of research in the MultiSector Dynamics, Earth, and Environmental System Modeling Program.
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How to make every day recycling day
(Family Features) With so many mixed messages, recycling can feel confusing, but the truth is simpler than you might think. Recycling isn’t just for today – it’s a year-round commitment to a healthier planet.
In honor of National Recycling Day, consider these facts about recycling from the experts and tips to make a difference.
Recycling Is Real
Americans recycle more than 6 billion pounds of plastic every year. Among the plastics recycled, polyethylene terephthalate (PET) remains a responsible material choice. PET is the world’s most recycled plastic, with more than 1.8 billion pounds of PET bottles and containers recovered in the U.S. annually. Since PET bottles can be made from 100% post-consumer recycled content, each recycled bottle contributes to a circular economy where materials are continuously reused instead of wasted.
Recycling PET Plastic is Better for the Environment
Countless others from academics, researchers and industry experts show plastics, such as PET specifically, often have a lower environmental impact. In fact, glass bottles produce three times the greenhouse gas emissions compared to PET bottles, and making an aluminum can produces twice the emissions, according to Life Cycle Assessment studies. Producing PET also uses less energy and water and lowers acid rain and smog potential. Using and recycling PET is a more responsible, more eco-friendly choice than banning plastic outright.
Recycling Saves Energy
Recycling PET bottles requires less energy than producing new glass bottles or aluminum cans. Every PET bottle you recycle helps conserve resources and supports a more responsible production cycle.
Not All Plastics are Created Equal
PET is a superstar among plastics because it can be recycled repeatedly without losing strength or quality. It’s also an inexpensive, lightweight and shatter-resistant package that preserves and protects the food and medicine people place in their bodies.
Recycling Can be Easy
Recycling services can be accessible, with many communities across the U.S. offering easy ways to recycle. Today more than 73% of all U.S. households have access to recycling, according to The Recycling Partnership.
By staying informed, choosing packaging that’s easily recyclable and recycling consistently, you can help build a more sustainable future every day. Visit recyclecheck.org to find out where you can recycle in your community.
5 Recycling Tips
- Know your plastics. Look for the No. 1 recycling symbol – inside three arrows forming a triangular shape – to identify polyethylene terephthalate (PET), helping ensure your recycling efforts are impactful.
- Recycle PET plastic packaging over bans. Choose products packaged in PET bottles where possible, as recycling PET reduces reliance on resource-heavy materials and greenhouse gas emissions.
- See recycling as energy conservation. PET bottle recycling uses significantly less energy compared to producing new glass bottles or aluminum cans.
- Think of recycling as an investment. Every PET container you recycle contributes to a circular economy and more sustainable world.
- Get involved within your community. Connect with local recycling programs and stay updated on your area’s recycling guidelines by visiting recyclecheck.org.
Photo courtesy of Shutterstock
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Amcor Rigid Packaging
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