The study, published in Nature Cities, reveals that all 28 most populous U.S. cities are experiencing some degree of land movement, with the majority sinking at varying rates due to a combination of factors including groundwater extraction, climate change, and human activities such as construction and urbanization.

Lead author Leonard Ohenhen, a postdoctoral researcher at Columbia Climate School’s Lamont-Doherty Earth Observatory, notes that as cities continue to grow, subsidence can become more pronounced, producing stresses on infrastructure that may exceed safety limits. “We will see more cities expand into subsiding regions,” he says.

The study uses satellite data to map land movements in the 28 cities, including Houston, which is experiencing some of the most rapid sinking, with over 40% of its area subsiding more than 5 millimeters per year. Other Texas cities, Fort Worth and Dallas, are also among the fastest-sinking, while areas around New York’s LaGuardia Airport and parts of Las Vegas, Washington, D.C., and San Francisco are experiencing localized fast-sinking zones.

Researchers found that groundwater removal for human use was responsible for 80% of overall sinkage, with compaction below ground level causing subsidence at the surface. Climate-induced droughts in some areas will likely worsen subsidence in the future, says Ohenhen.

The study also reveals that natural forces are at work in some areas, such as the weight of ancient ice sheets that once covered much of interior North America. Even today, some cities like New York, Indianapolis, Nashville, Philadelphia, Denver, Chicago, and Portland are still subsiding due to these bulges, with rates ranging from 1 to 3 millimeters per year.

The researchers emphasize that continued population growth and water usage will likely exacerbate subsidence in the future. They recommend that cities focus on solutions such as land raising, enhanced drainage systems, and green infrastructure to mitigate flooding, and retrofitting existing structures to address tilting hazards.

Ohenhen concludes, “We have to move to solutions.” The study was coauthored by researchers from various institutions and provides a valuable resource for policymakers and urban planners to address the challenges posed by subsidence in major American cities.

In a groundbreaking study, researchers from the University of Exeter and Fishtek Marine have discovered that fitting fishing pots with LED lights can significantly increase catches of northern shrimp and other species. The findings hold promise for developing more sustainable and low-impact fishing practices.

The trial, conducted off Scotland’s west coast, showed that illuminated pots caught up to 19 times more northern shrimp than unlit ones. Moreover, the pots also attracted fish, which could lead to the development of new trap fisheries for larger species like cod.

According to Dr. Robert Enever from Fishtek Marine, “the light attracts zooplankton – like moths around a flame – which in turn attracts shrimp (which eat zooplankton), and that entices larger fish predators into the pots to gobble up the shrimp.” This “attraction cascade” creates a self-baiting pot, making it an attractive option for sustainable fishing.

While the trial’s catch rates were not commercially viable for northern shrimp, the authors suggest that this could change in areas with higher shrimp populations. Additionally, the high catch rates of fish, including juvenile poor cod, indicate that light-based traps could be used to develop low-impact fisheries for these species.

Dr. Tom Horton from the Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall emphasizes the importance of finding lower-impact alternatives, such as static gear like pots, to reduce bycatch and habitat disturbance associated with trawling. “Shrimp and cod are often fished by trawling, which can result in high bycatch (accidental catching of other species), and habitat disturbance,” he notes.

The study was funded by the UK Seafood Innovation Fund and Schmidt Marine Technology Partners. The research paper, published in Ocean and Coastal Management, provides valuable insights into the potential for light-based traps to enhance sustainable fishing practices.

The study, led by George Washington University in collaboration with scientists from Washington University in St. Louis and the University of North Carolina at Chapel Hill, has mapped air pollution levels and carbon dioxide emissions across 13,189 urban areas worldwide. This comprehensive global analysis provides a powerful snapshot of how urban environments are evolving across the globe.

The research team used data from satellite observations, ground-based measurements, and computer models to measure city-level air pollution and the average amount of carbon dioxide released into the atmosphere between 2005-2019. According to Susan Anenberg, professor of environmental and occupational health at the GW Milken Institute School of Public Health, “This study shows that progress is possible but uneven, with some cities seeing worsening pollution while others are experiencing cleaner air over time.”

Key findings from the study include:

* More than 50% of cities showed links between all pollutants, suggesting they likely come from the same sources and could be reduced together.
* Urban areas in high-income regions with aggressive environmental policies saw simultaneous declines in all pollutants.
* Cities in regions undergoing rapid population and economic growth, including South Asia and parts of Africa, experienced rising pollution and emissions levels.
* Satellite remote sensing provides an unprecedented opportunity to track pollution levels in all cities worldwide.

The study’s integrated approach offers policymakers, researchers, and climate advocates a valuable new tool for assessing the effectiveness of strategies to reduce pollution. By tracking historical pollutant trends and analyzing correlations across air pollution, nitrogen dioxide, and carbon dioxide emissions, the study offers insights into how urban areas can make progress on both climate and public health goals.

Researchers have also created an interactive map and dashboard to track air pollution in cities worldwide, providing a valuable resource for policymakers, researchers, and climate advocates.