Sargassum biomass in the north Sargasso Sea declined drastically since 2015, co-occurring with related reductions in the northwest Gulf of Mexico and an expansion of the Great Atlantic Sargassum Belt, according to in situ and satellite observations.

Storms cool the Southern Ocean surface in summer mainly by deepening the mixed layer, but increased air–sea turbulent fluxes reduce ocean heat loss and partly offset the cooling, according to glider observations, reanalyses and satellite data.

Samples returned from asteroid Bennu contain bio-essential sugars such as ribose and glucose that may have formed in the parent asteroid from brines containing formaldehyde, according to a geochemical study.

Antarctic Bottom Water progressively filled more of the deep Southern Ocean through the last deglaciation, potentially contributing to the increase in atmospheric CO₂, according to neodymium isotope records from the Weddell–Enderby Basin.

Drainage of two surface lakes on Greenland’s fastest ice stream caused a pulse of faster flow to propagate downstream and triggered a long calving episode, suggesting the entire stream is strongly coupled, according to geophysical field observations.

Mass-wasting deposits that accumulated against mid-ocean ridge faults have high porosity in which calcium carbonate precipitated, storing seawater carbon dioxide, as revealed by cores of a 61-million-year-old seafloor talus deposit.

Flash floods must be placed at the heart of Earth system science and global climate adaptation efforts, as they increasingly define hydroclimate risk in a warming world.

The eruption of Nevado del Ruiz volcano in Colombia in November 1985 killed an estimated 25,000 people in the town of Armero. Forty years on, Colombia has transformed its geological risk management in the wake of this disaster, recognizing the importance of institutions, knowledge sharing and engagement with local communities.

The aftermath of volcanic eruptions often reveals critical gaps in hazard and risk management. Effective global implementation of the lessons learned from disasters triggered by natural hazards is long overdue.

Volcanic disaster risk reduction has greater impact when rooted in community experience. We must recognize the importance of Indigenous knowledge to shape more culturally situated, equitable, respectful, and effective mitigation strategies.

Since the 1985 Nevado del Ruiz eruption that killed over 23,000 people in Armero, Colombia, risk communication has become central to volcanic crisis management. Despite the development of effective tools and programmes for volcanic risk communication, considerable challenges remain.