geophysics

The geomagnetic field protects Earth from harmful cosmic radiation. Over the past two centuries, this field has weakened, coinciding with the growth of the South Atlantic Anomaly—a region of reduced magnetic intensity spanning South America and the South Atlantic Ocean—which poses risks to satellites and space missions. Research led by a Spanish team shows that this anomaly is a recurring event on timescales ranging from centuries to millennia, according to a reconstruction of the geomagnetic field over the past 2,000 years. The study, published in PNAS, shows that the current anomaly emerged after the year 1100 in the Indian Ocean and crossed Africa before reaching South America.

A study in 2024 described how the Earth's core had slowed down its rotation speed in recent decades. Now, the same international team of scientists adds that its shape has also changed over the last two decades. Until now, it was thought that both processes could not occur simultaneously. According to the researchers, who publish the results in the journal Nature Geoscience, the finding could improve our knowledge of the core's properties and structure.

Climate change is influencing the length of the day, according to an analysis published in PNAS. As melting ice accelerates due to rising temperatures, sea levels rise and large masses move from the polar to the equatorial regions. This redistribution affects the Earth's rotation and results in longer days. During the 20th century, sea level variations were associated with changes in day length between 0.3 and 1 millisecond per century, but since 2000 this variation has increased to 1.33 (±0.03) milliseconds per century and the authors estimate that it will accelerate further in the coming decades.

A publication in the journal AIP Advances reports the detection over the tropics of a large ozone hole, defined as an area where more than 25% of the usual ozone has been lost. The hole would be comparable in depth to the well-known hole over Antarctica, but would cover an area seven times larger.

Volcanic monitoring in the Canary Islands must be constant. Not only because the archipelago is "one of the most interesting active volcanic regions on the planet", according to the IGN, but above all because "volcanism in the Canary Islands poses a potential risk to some two million people" who live on the islands or visit them as tourists.