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Rivers are critical corridors that connect cities and ecosystems alike. When drought develops, water levels fall, making river navigation harder and more expensive. In 2022, water levels in some of the world’s largest rivers, including the Rhine in Europe and the Yangtze in China, fell to historically low levels. The Mississippi River fell so low in Memphis, Tennessee, in mid-October that barges were unable to float, requiring dredging and special water releases from upstream reservoirs to keep channels navigable. Conditions on the lower Mississippi may be easing somewhat, thanks to early winter rains. But as Earth scientists at the University of Memphis, we see this year’s dramatic plunge in water levels as a preview of a climate-altered future. River barges are an efficient way to transport bulk commodities, such as grain shipments, and heavy equipment over long distances. But that’s true only for normal water conditions. Increased swings between extreme low...

Many of the ocean’s most charismatic animals spend their lives swimming, flying or gliding thousands of miles, from the coasts to the high seas. Arctic terns, humpback whales and sea turtles are examples. Scientists have spent many years documenting and studying these magnificent journeys. Chronicling where these species go is just the beginning. The next steps are understanding when and how far each animal travels and what triggers it to roam. We are a marine biologist and an evolutionary ecologist and have worked together to study the nesting and migration habits of endangered olive ridley sea turtles (Lepidochelys olivacea). This information is vital for managing the turtles’ recovery – but our research shows that two identical-looking olive ridleys may follow very different paths. Approximate range of olive ridley sea turtles. NOAA Protecting animals that move Mapping the s...

As part of its effort to reduce air pollution and cut greenhouse gas emissions that contribute to climate change, California is pursuing aggressive policies to promote clean trucks. The state already requires that by 2035, all new cars and other light-duty vehicles sold in the state must be zero emission. Its powerful Air Resources Board has adopted rules requiring that most trucks be zero emission by 2035, and is now proposing that all trucks sold by 2040 must be zero emission. The Conversation asked a panel of transportation experts from the University of California, Davis what’s involved in such a rapid transition. 1. Why is California targeting medium- and heavy-duty trucks? Although diesel engines are valuable for moving heavy loads, they also are major polluters. Diesel trucks account for one-fourth of greenhouse gas emissions and about half of conventional air pollution from transportation in U.S. cities. Pollutants in diesel exhaust include nitrogen oxides, fine...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. How many Amazon packages get delivered each year? – Aya K., age 9, Illinois It’s incredibly convenient to buy something online, right from your computer or phone. Whether it’s a high-end telescope or a resupply of toothpaste, the goods appear right at your doorstep. This kind of shopping is called “e-commerce” and it’s becoming more popular each year. In the U.S., it has grown from a mere 7% of retail purchases in 2012 to 19.6% of retail and US$791.7 billion in sales in 2020. Amazon’s growing reach For Amazon, the biggest player in e-commerce, this means delivering lots of packages. In 2021 the company shipped an estimated 7.7 billion packages globally, based on its nearly $470 billion in sal...

Russia’s effort to conscript 300,000 reservists to counter Ukraine’s military advances in Kharkiv has drawn a lot of attention from military and political analysts. But there’s also a potential energy angle. Energy conflicts between Russia and Europe are escalating and likely could worsen as winter approaches. One might assume that energy workers, who provide fuel and export revenue that Russia desperately needs, are too valuable to the war effort to be conscripted. So far, banking and information technology workers have received an official nod to stay in their jobs. The situation for oil and gas workers is murkier, including swirling bits of Russian media disinformation about whether the sector will or won’t be targeted for mobilization. Either way, I expect Russia’s oil and gas operations to be destabilized by the next phase of the war. The explosions in September 2022 that damaged the Nord Stream 1 and 2 gas pipelines from Russia to Europe, an...