TheConversation

Milton Orr looked across the rolling hills in northeast Tennessee. “I remember when we had over 1,000 dairy farms in this county. Now we have less than 40,” Orr, an agriculture adviser for Greene County, Tennessee, told me with a tinge of sadness. That was six years ago. Today, only 14 dairy farms remain in Greene County, and there are only 125 dairy farms in all of Tennessee. Across the country, the dairy industry is seeing the same trend: In 1970, over 648,000 U.S. dairy farms milked cattle. By 2022, only 24,470 dairy farms were in operation. While the number of dairy farms has fallen, the average herd size – the number of cows per farm – has been rising. Today, more than 60% of all milk production occurs on farms with more than 2,500 cows. Dairy farm numbers have fallen over the past few decades, but larger farms have kept the overall number of cows fairly steady. USDA Thi...

Summer 2024 was officially the Northern Hemisphere’s hottest on record. In the United States, fierce heat waves seemed to hit somewhere almost every day. Phoenix reached 100 degrees for more than 100 days straight. The 2024 Olympic Games started in the midst of a long-running heat wave in Europe that included the three hottest days on record globally, July 21-23. August was Earth’s hottest month in the National Oceanic and Atmospheric Administration’s 175-year record. Overall, the global average temperature was 2.74 degrees Fahrenheit (1.52 degrees Celsius) above the 20th-century average. That might seem small, but temperature increases associated with human-induced climate change do not manifest as small, even increases everywhere on the planet. Rather, they result in more frequent and severe episodes of heat waves, as the world saw in 2024. The most severe and persistent heat waves are often associated with an atmospheric pattern called a heat dome. As a...

Climate change can seem like an insurmountable challenge. However, if you look closely at its causes, you’ll realize that history is filled with similar health and environmental threats that humanity has overcome. The main cause of climate change – carbon dioxide from the burning of fossil fuels – is really just another pollutant. And countries know how to reduce harmful pollutants. They did it with the pesticide DDT, lead paint and the power plant emissions that were causing acid rain, among many others. In each of those cases, growing public outcry eventually led to policy changes, despite pushback from industry. Once pressured by laws and regulations, industries ramped up production of safer solutions. I am an earth and environmental scientist, and my latest book, “Reclaiming Our Planet,” explores history’s lessons in overcoming seemingly insurmountable hazards. Here are a few examples: Banning DDT despite industry pushback DDT was the f...

Citrus trees showing natural tolerance to citrus greening disease host bacteria that produce novel antimicrobials that can be used to fight off the disease, our recent study shows. We found the trees at an organic farm in Clermont, Florida. Citrus greening disease – known more formally as Huanglongbing, or HLB, is caused by the bacterium Candidatus Liberibacter asiaticus. It is spread by an insect called the Asian citrus psyllid. There is no known cure for the disease. We are Florida-based researchers who study sustainable farming practices, a discipline also known as agroecology. Our team has isolated these antimicrobial compounds in the lab and is now working to test them with the goal of producing an effective treatment for HLB. Why it matters HLB has dealt a massive blow to Florida’s iconic citrus industry. Since citrus greening disease was first detected in the state in 2005, Florida citrus production is down by more than 92%. The disease is just one factor....

A container ship rammed into the Francis Scott Key Bridge in Baltimore around 1:30 a.m. on March 26, 2024, causing a portion of the bridge to collapse into Baltimore Harbor. Officials called the event a mass casualty and were searching for people in the waters of the busy port. This event occurred less than a year after a portion of Interstate 95 collapsed in north Philadelphia during a truck fire. That disaster was initially expected to snarl traffic for months, but a temporary six-lane roadway was constructed in 12 days to serve motorists while a permanent overpass was rebuilt. U.S. cities often face similar challenges when routine wear and tear, natural disasters or major accidents damage roads and bridges. Transportation engineer Lee D. Han explains how planners, transit agencies and city governments anticipate and manage these disruptions. How do agencies plan for disruptions like this? Planning is a central mission for state and metropolitan transportation agencies. T...