New Arizona State University-led research findings from studying over two decades of satellite observations reveal that the Earth’s continents have experienced unprecedented freshwater loss since 2002, driven by climate change, unsustainable groundwater use and extreme droughts. The study highlights the emergence of four continental-scale “mega-drying” regions, all located in the northern hemisphere, and warns of severe consequences for water security, agriculture, sea level rise, and global stability. The research team reports that drying areas on land are expanding at a rate roughly twice the size of California every year. And, the rate at which dry areas are getting drier now outpaces the rate at which wet areas are getting wetter, reversing long-standing hydrological patterns. The negative implications of this for available freshwater are staggering. 75% of the world’s population lives in 101 countries that have been losing freshwater for the past 22 years.

Metal sulfides with seven to eight d electrons show optimal performance as catalysts for water electrolysis, as reported by researchers from Institute of Science Tokyo. In a comprehensive analysis of various metal sulfides, they identified a volcano-shaped relationship between catalytic activity and the number of d electrons in metal atoms. This newly uncovered principle will form the basis of catalyst design guidelines, accelerating the development of efficient water-splitting catalysts for green hydrogen production.

The global marine heatwaves (MHWs) of 2023 were unprecedented in their intensity, persistence, and scale, according to a new study. The findings provide insights into the region-specific drivers of these events, linking them to broader changes in the planet’s climate system. They may also portend an emerging climate tipping point. Marine heatwaves (MHWs) are intense and prolonged episodes of unusually warm ocean temperatures. These events pose severe threats to marine ecosystems, often resulting in widespread coral bleaching and mass mortality events. They also carry serious economic consequences by disrupting fisheries and aquaculture. It’s widely understood that human-driven climate change is driving a rapid increase in the frequency and intensity of MHWs. In 2023, regions across the globe, including the North Atlantic, Tropical Pacific, South Pacific, and North Pacific, experienced extreme MHWs. However, the causes underlying the onset, persistence, and intensification of widespread MHWs remain poorly understood.

To better understand the MHWs of 2023, Tianyun Dong and colleagues conducted a global analysis using combined satellite observations and ocean reanalysis data, including those from the ECCO2 (Estimating the Circulation and Climate of the Ocean-Phase II) high-resolution project. According to the findings, MHWs of 2023 set new records for intensity, duration, and geographic extent, lasting four times the historical average and covering 96% of the global ocean surface. Regionally, the most intense warming occurred in the North Atlantic, Tropical Eastern Pacific, North Pacific, and Southwest Pacific, collectively accounting for 90% of the oceanic heating anomalies. Dong et al. show that the North Atlantic MHW, which began as early as mid-2022, persisted for 525 days, while the Southwest Pacific event broke prior records with its vast spatial extent and prolonged duration. What’s more, in the Tropical Eastern Pacific, temperature anomalies peaked at 1.63 degrees Celsius during the onset of El Niño. Using a mixed-layer heat budget analysis, the authors discovered diverse regional drivers contributing to the formation and persistence of these events, including increased solar radiation due to reduced cloud cover, weakened winds, and ocean current anomalies. According to the authors, the 2023 MHWs may mark a fundamental shift in ocean–atmosphere dynamics, potentially serving as an early warning of an approaching tipping point in Earth’s climate system.

A first-of-its-kind experiment tracing evolution across 25 generations shows that tiny crustaceans at the heart of the ocean food web rely on a largely unknown biological toolkit to survive the stresses of climate change. The study reveals that it’s not only genetic changes that help these animals adapt to warming and acidifying ocean conditions. In addition, little-known epigenetic changes play a crucial role too. Remarkably, the researchers led by Melissa Pespeni at the University of Vermont discovered that the two mechanisms operate independently offering a two-pronged strategy for resilience. Until now, few studies have tracked genetic and epigenetic changes in tandem over many generations. This experiment is one of the first to do so in a long-term, replicated evolution study—offering some of the strongest evidence yet that epigenetic change can help populations survive and perhaps allow future genetic adaptation. Which means that copepods may be tougher under the stresses of a warming ocean than scientists previously would have predicted. And that could be good news for the fish species who eat copepods as primary prey—and many other creatures.