More than one-third of all animals on Earth, from beetles to cows to elephants, depend on plant-based diets. Plants are a low-calorie food source, so it can be challenging for animals to consume enough energy to meet their needs. Now climate change is reducing the nutritional value of some foods that plant eaters rely on. Some studies suggest that this 'greening of the Earth' could partially offset rising greenhouse gas emissions by storing more carbon in plants. However, there's a trade-off: These fast-tracked plants can contain fewer nutrients per bite. I'm an ecologist and work with colleagues to examine how nutrient dilution could affect species across the food web. Our focus is on responses in plant-feeding populations, from tiny grasshoppers to giant pandas. We believe long-term changes in the nutritional value of plants may be an underappreciated cause of shrinking animal populations. These changes in plants aren't visually evident, like rising seas. Nor are they sudden and imminent, like hurricanes or heat waves. But they can have important impacts over time....
Companies behind these 'mass timber' projects say that wood is a lower-carbon alternative to steel or concrete and brings other benefits, such as faster construction time and lower cost than concrete and steel. Advocates say the wood materials, made of compressed layers of wood with glue, offer good fire safety as well. As an economist who studies forestry and natural resources, I took an interest in this building trend when I heard that a local bar on campus was going to be replaced by a 13-story building made out of wood. I see any increase in the use of wood in buildings as positive for reducing the substantial carbon footprint of buildings. But it is critical to consider where wood is sourced and whether forests are managed sustainably. One life-cycle analysis found that using mass timber in a 12-story building in Oregon had an 18% lower global warming impact compared with constructing the building with steel-reinforced concrete. The carbon emissions benefits are even greater when comparing timber with steel for low- and mid-rise buildings. In these studies, the global warming benefits mostly result from lower emissions in sourcing, transporting and manufacturing the material for these large wood buildings, compared with steel or concrete components, rather than efficiencies in heating or cooling or disposal of the materials at the end of the building's lifespan....
Cordelia Bahr is part of Nature's 10, a list of people who shaped science in 2024....
every year, at the beginning of November, one of the most impressive natural spectacles in the world takes place in Michoacan, Mexico. Hundreds of millions of migrating monarch butterflies settle in the forested massifs of the country's Monarch Butterfly Biosphere Reserve, roughly 100 kilometers west of Mexico City. Having flown south for eight months, beginning their journey in the northern United States or southern Canada, they hibernate here for the winter before mating in the spring. After flying for more than 4,000 kilometers, the butterflies land in the oyamel fir trees of the Ejido el Rosario region, where for weeks they congregate, protecting themselves from the wind and the cold nights. Without these trees, the butterflies would not be able to survive their exhausting journey. The oyamel fir grows in a very small climatic space, one that is humid yet cold. 'Its distribution is very limited to the highest mountains in central Mexico,' says Cuauhtemoc Saenz Romero, a professor at the Universidad Michoacana de San Nicolas de Hidalgo. Saenz Romero is the lead author of a recent study that anticipates that this forest will gradually deteriorate to the point of disappearance as a result of climate change, endangering the butterflies....