TheConversation

Many sharks and rays are known to breach, leaping fully or partly out of the water. In a recent study, colleagues and I reviewed research on breaching and ranked the most commonly hypothesized functions for it. We found that removal of external parasites was the most frequently proposed explanation, followed by predators chasing their prey; predators concentrating or stunning their prey; males chasing females during courtship; and animals fleeing predators, such as a ray escaping from a hammerhead shark in shallow water. We found that the highest percentage of breaches, measured by the number of studies that described it, occurred in manta rays and devil rays, followed by basking sharks and then by eagle rays and cownose rays. However, many other species of sharks, as well as sawfishes and stingrays, also perform this behavior. A breaching white shark surprises researchers off Cape Cod, Massachusetts. Why it matters It takes a lot of ene...

Plastic is a fast-growing segment of U.S. municipal solid waste, and most of it ends up in the environment. Just 9% of plastic collected in municipal solid waste was recycled as of 2018, the most recent year for which national data is available. The rest was burned in waste-to-energy plants or buried in landfills. Manufacturers assert that better recycling is the optimal way to reduce plastic pollution. But critics argue that the industry often exaggerates how readily items can actually be recycled. In September 2024, beverage company Keurig Dr Pepper was fined US$1.5 million for inaccurately claiming that its K-Cup coffee pods were recyclable after two large recycling companies said they could not process the cups. California is suing ExxonMobil, accusing the company of falsely promoting plastic products as recyclable. Environmental law scholar Patrick Parenteau explains why claims about recyclability have confused consumers, and how forthcoming guidelines from the U.S. Federa...

As a child growing up in the early 1990s, I remember learning in school about the greenhouse effect. Carbon dioxide released by burning fossil fuels traps heat near the Earth’s surface, like the glass of a greenhouse. I imagined myself on the playground, roasting inside a humid hothouse. Fast forward 30 years, and the terms have changed. For a while, “global warming” was the go-to expression for talking about rising global temperatures and the role of human activities, particularly the use of fossil fuels. It had a spike in internet searches in 2007, probably due to former Vice President Al Gore’s documentary “An Inconvenient Truth: A Global Warning,” which hit theaters in 2006. Near the end of the Obama administration, “climate change” became the most common term. It’s now trending in Google searches more than global warming. Both terms make the same point: Rising global temperatures have major consequences on local weather...

Kids born in 2020 worldwide will experience twice the number of wildfires during their lifetimes compared with those born in 1960. In California and other western states, frequent wildfires have become as much a part of summer and fall as popsicles and Halloween candy. Wildfires produce fine particulate matter, or PM₂.₅, that chokes the air and penetrates deep into lungs. Researchers know that short-term exposure to wildfire PM₂.₅ increases acute care visits for cardiorespiratory problems such as asthma. However, the long-term effects of repeated exposure to wildfire PM₂.₅ on chronic health conditions are unclear. One reason is that scientists have not decided how best to measure this type of intermittent yet ongoing exposure. Environmental epidemiologists and health scientists like us usually summarize long-term exposure to total PM₂.₅ – which comes from power plants, industry and transportation – as average exposure...

Hunting large carnivores is a contentious issue in wildlife management and conservation. It’s on the ballot in fall 2024 in Colorado, where voters will consider Proposition 127, a proposed ban on hunting and trapping of mountain lions, bobcats and lynx in the state. Wildlife agencies often use regulated hunting as a tool for controlling carnivore populations, reducing their impacts on vulnerable wildlife or minimizing the risk of conflict between carnivores and people, pets and livestock. But scientific studies have questioned how effectively recreational hunting achieves these goals. And public attitudes are shifting as participation in hunting declines. We direct Colorado State University’s Center for Human-Carnivore Coexistence and Animal-Human Policy Center. Together with our colleague Benjamin Ghasemi, we recently surveyed Colorado residents about their perceptions of hunting mountain lions and black bears in the state. We found that support for hunting depen...