Science Talk: Invisible Water in a Changing Climate: Groundwater, Drought, and Water Security - UNU | United Nations University

IntroductionOffshore freshened groundwater (OFG) is subsurface porewater with salinity below that of ambient seawater, occurring in sediments and rocks beneath or seaward of the shoreline. The definition refers to a salinity state rather than to a process and this distinction led to a recent proposal to rename the phenomenon Offshore Relatively Fresh Groundwater (ORFG), since "freshened" can be read as implying ongoing change1. OFG has emerged as a significant yet poorly constrained part of the global hydrological cycle, with reservoirs identified along continental margins worldwide2,3. Global water stress is growing, particularly in densely populated coastal regions. OFG is also of broader scientific importance for understanding geohazards, biogeochemical cycling, subseafloor microbiology, and the preservation of archaeological records. There is therefore an urgent need to better constrain the emplacement, stability, and distribution of OFG2,3,4,5,6,7,8,9,10.

Lawrence Livermore National Laboratory researcher Isaiah Santistevan led the development of three-dimensional simulations exploring how a nuclear device could deflect or disrupt an asteroid threatening Earth. Credit: Blaise Douros/LLNL Lawrence Livermore National Laboratory (LLNL) researchers are developing three-dimensional simulations to examine how a nuclear device could be used to deflect or potentially disrupt an asteroid threatening Earth.

Milky Way’s first microblazar candidate sits 12,000 light-years away, offering a rare ground-level lab for studying relativistic jetsA black hole 12,000 light-years away is firing a jet of plasma almost directly toward Earth. At that distance, no known or expected danger to Earth has been identified by the researchers or the institutions involved. What astronomers have actually found is rarer and more interesting than a threat. Researchers have identified IRAS 18293-0941 as a compelling candidate for the Milky Way’s first microblazar, a class of object that gives astrophysicists a close-up laboratory for studying some of the most violent physics in the galaxy. What Astronomers FoundThe discovery centers on a binary system whose black hole expels plasma jets at close to three-quarters the speed of light, pointed almost directly toward Earth. The system pairs a hot, massive star with a black hole that completes a full orbit roughly every 11.38 days. Material drawn from the companion star feeds the black hole, and some of that matter gets expelled outward as opposing jets traveling at approximately three-quarters the speed of light. Terminology matters here.

Forests that stood on Mozambique's coast thousands of years ago now lie beneath shallow seas, and they have become fish-filled "peat reefs" with marine life comparable to coral reefs, researchers report in Scientific Reports. A team from the Bazaruto Center for Scientific Studies (BCSS) Ocean Observatory, led by Mario Lebrato, documented the submerged peat in the Bazaruto Archipelago in the Western Indian Ocean. BCSS, founded in 2017, describes itself as Africa's first permanent ocean observatory. Working with universities and institutions in the U. K., U. S. and Canada, the team believes it has carried out the first ecological study of peat reefs anywhere in the tropics. Old forests, new seafloorRadiocarbon dating shows the peat formed between about 300 and 5,000 years ago, and chemical analysis indicates it came mostly from coastal land plants and trees. Some samples contain up to 40% organic carbon by dry weight. Lebrato said the coastline has very little natural hard seabed, mostly shifting sand. As rising seas expose the old peat layers, they create rare solid habitat where marine life can settle, hide and feed.