Spanish Institute of Oceanography

Targeted marine cloud bleaching is a proposed geoengineering method to increase the amount of light reflected by clouds and reduce the heat reaching Earth. A US team has taken advantage of a natural experiment that generated this effect—through aerosols produced by the massive Australian bushfires of 2019 and 2020—to study the possibilities and risks of using it to modify an extreme weather event like El Niño. According to the models used in the study, its early application could weaken El Niño, but it could also have unintended consequences, such as altering the timing and increasing the magnitude of the subsequent La Niña event. The work is published in Science Advances.

Two Copernicus services have independently confirmed that global sea surface temperatures have broken records for this time of year. Daily data from the Copernicus Climate Change Service exceeded the 2024 levels on 21 June, reaching 20.86 °C, higher than the 20.83 °C recorded in 2023 and 2024. Data from the Copernicus Marine Watch Service show temperatures of 21.0 °C on 21 June, beating the 2023 and 2024 records by 0.1 °C. This unprecedented warming is linked to the onset of El Niño (announced by the WMO and declared by NOAA on 11 June) and to record-breaking sea surface temperatures in the North Pacific; consequences are anticipated for weather patterns, the global climate and marine ecosystems.

New research analysing more than 33,000 fish populations in the northern hemisphere between 1993 and 2021 reveals that chronic ocean warming is driving a long-term decline in biomass of up to 19.8% per year for species in the Mediterranean, North Atlantic and North-East Pacific. At the same time, in the short term, more fish are thriving in cold areas due to the heat, but these increases are temporary and the authors warn that relying on them would lead to unsustainable exploitation. The study, by the National Museum of Natural Sciences (MNCN-CSIC) and the National University of Colombia, is published in Nature Ecology & Evolution.

Since 2013, undeclared and uncertified exports of fins from five overexploited shark species have been illegal. Now, an international team has determined that illegal fins from four of those species remained prevalent in the market between 2015 and 2021. Among the countries cited as potential violators are Spain, China, and Taiwan. The study is published in the journal Science Advances.

Since the implementation of protective closures in 2022, bottom fishing in European waters has declined by 81% in 87 vulnerable marine ecosystems located at depths of 400-800 metres, a study published in Science Advances reveals. However, according to the authors, these deep-water regions continued to receive many incursions by Spanish and French vessels.

An assessment of the extinction risk of freshwater fauna, covering more than 23,000 species, reveals that around 24% of the species studied are at risk of extinction. The analysis, published in Nature, identifies the main threats from pollution, dams, agriculture and invasive species. Decapods - such as freshwater crabs and shrimps - have the highest percentage of threatened species (30 %), followed by freshwater fish (26 %) and odonates - such as dragonflies (16 %).

A review published in the journal Science Advances examines how the expansion of marine aquaculture - the farming of aquatic organisms in the ocean - can lead to risks, such as degradation of the marine environment. The study is part of a special issue of the journal dedicated to this growing industry.

Mercury concentrations in tuna have remained stable between 1971 and 2022, even though emissions of this metal from human activities have decreased over the same period, a study says. 'Aggressive' emission reduction targets are needed to achieve measurable declines in concentrations of this pollutant, which is toxic for human health, the authors write in the journal Environmental Science & Technology Letters. The Minimata Convention on Mercury, a global treaty that entered into force in 2017, bans new mercury mines and includes provision to reduce mercury use, but mercury has already accumulated in the ocean 'for centuries', the article says.

According to a new report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), human activities have introduced over 37,000 exotic species to regions around the world. The document highlights that more than 3,500 of these are harmful invasive exotic species that are often overlooked until it's too late.

The deadline passed and after two marathon nights of meetings, the delegations of the UN member states have managed to reach an agreement to make the so-called Oceans Treaty - or BBNJ Treaty, Biodiversity Beyond National Jurisdiction - a reality. New York City has seen the fifth session of this conference bear fruit with an agreement on the wording of the text, seventeen years after the talks began and with negotiations stalled last August due to a lack of agreement. The Treaty aims to protect and regulate the use of areas beyond national jurisdiction, which account for more than 60% of the oceans, or almost half of the planet. Marine genetic resources and how to share these benefits has been one of the main stumbling blocks.