An alarming reduction in Earth’s freshwater supply has been identified through data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites. This trend, which began in May 2014, highlights a significant shift in global water availability, according to findings published in Surveys in Geophysics. The research, conducted by an international team of scientists, points to a persistent drier phase for the planet, with freshwater reserves remaining below average levels.

Key Findings from GRACE Satellite Data

The GRACE mission, operated jointly by NASA and German research centres, revealed that global freshwater reserves between 2015 and 2023 measured approximately 1,200 cubic kilometres—equivalent to two-and-a-half times the volume of Lake Erie. These measurements encompass surface water, underground aquifers, and other freshwater sources.

Matt Rodell, a hydrologist at NASA’s Goddard Space Flight Centre, stated in a press release that this reduction reflects a departure from pre-2014 averages.

Droughts and Global Warming Linked to Freshwater Loss

Research highlighted the occurrence of 13 major droughts globally since 2015, affecting regions such as Central Brazil, Australasia, and parts of Africa and Europe. These droughts have coincided with record high global temperatures, raising concerns about climate change’s role in exacerbating water shortages.

Michael Bosilovich, a meteorologist at NASA Goddard, indicated that rising temperatures have intensified droughts by altering precipitation patterns, leading to runoff rather than groundwater replenishment.

Uncertainty Surrounding Long-Term Impact

While these findings underline the urgent need for sustainable water management, some researchers remain cautious about drawing definitive links between global warming and the observed trends. Susanna Werth, a hydrologist from Virginia Tech, pointed out the inherent uncertainties in climate models, emphasising the need for continued monitoring.

Whether Earth’s freshwater supplies will recover remains uncertain, but the observed decline could foreshadow prolonged dry conditions, scientists warn.

A 16th-century mask, believed to symbolise the Aztec fire god Xiuhtecuhtli, has been displayed at the British Museum in London. Crafted from Spanish cedar and adorned with turquoise mosaic, mother-of-pearl eyes, gold rims, and conch shell teeth, the artefact is considered a remarkable example of Aztec artistry. Measuring 16.8 centimetres tall, its intricate details include small temple holes suggesting it may have been worn or mounted. Inside, cinnabar, a mercury-rich mineral, lines the mask.

Historical Origins and Significance

The mask is thought to have originated in Mesoamerica between 1400 and 1521, during the height of the Aztec Empire. Scholars associate it with treasures seized by Spanish conquistador Hernán Cortés during his conquest. Xiuhtecuhtli, known as the “turquoise lord” in the Nahuatl language, was central to Aztec mythology as the god of fire and renewal.

Central to Aztec rituals was the “new fire ceremony,” held every 52 years. As narrated by the British Museum, during this ritual, the holy fire was extinguished across the land and reignited by priests. A sacrificial victim played a pivotal role in this renewal rite, with flames being kindled on their chest before their heart was offered to the fire. Masks like this one are believed to have been integral to such ceremonies.

Interpreting the Mask’s Iconography

The mask’s design incorporates darker turquoise pieces forming a butterfly motif, another symbol of renewal in Aztec culture. While it is widely attributed to Xiuhtecuhtli, experts suggest it might instead depict Nanahuatzin, the wart-faced deity who mythologically became the sun after self-sacrifice. The ambiguity surrounding its representation reflects the complex symbolism within Aztec art.

The turquoise mask stands as a vivid link to Aztec civilisation’s spiritual practices, offering insights into their cultural emphasis on fire, renewal, and transformation.

Scientists are developing an alternative navigation system that utilises mobile signals to assist pilots if GPS fails, according to a study conducted by Sandia National Laboratories and Ohio State University. The system relies on signals from cell towers and communication satellites, offering a safety net for airborne navigation systems. The initiative aims to mitigate risks associated with GPS failures, which can occur due to technical malfunctions, malicious interference, or in areas of conflict.

Testing and Early Results

The global positioning system, consisting of 31 satellites, is certified by the US Federal Aviation Administration (FAA) to provide precise navigation data. However, it remains vulnerable to jamming and hacking, raising concerns about its reliability in critical situations.

The research team, led by Jennifer Sanderson, an electrical engineer at Sandia National Laboratories, said in a statement that to counter these challenges through a technology that employs “signals of opportunity”—unintentional signals like those from mobile networks and satellites.

As reported by Sandia National Laboratories, experimental trials have utilised weather balloons to carry antenna payloads into the stratosphere, achieving altitudes up to 82,000 feet (25,000 metres). These payloads capture signals from communication satellites and cell towers, potentially providing pilots with navigational data during GPS disruptions.

Initial findings suggest that cell tower signal beacons can be detected at such altitudes, though the process currently requires manual analysis to identify individual signals. Researchers plan to enhance the system using algorithms capable of real-time signal identification and positional calculations.

Challenges and Future Developments

While the system shows promise, obstacles remain. Communication satellites focus their signals towards Earth’s surface, making it challenging to detect them effectively at high altitudes. The researchers are working on improving detection capabilities and reducing errors to ensure the technology’s practicality for aviation.

If successfully implemented, this navigation system could significantly bolster aviation safety by providing a reliable backup for GPS, reducing risks associated with its failure during flights.