oceanography

Researchers have reviewed nearly 400 scientific articles related to sea level rise and associated risks and concluded that most studies may have underestimated global sea level rise by an average of 0.3 meters. In some areas of the Global South, these levels could be up to 1 meter higher than previously thought. According to the authors, a reassessment of the methodology used to characterize the impact of sea level rise is necessary, as this could have implications for policy, climate finance, and coastal adaptation plans. The study is published in Nature.

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.

According to a study compiling data from 10,000 marine animal necropsies, 35% of birds, 12% of mammals, and 47% of turtles examined had ingested macroplastics, causing death in 1.6%, 0.7%, and 4.4% of these animals, respectively. The types of plastic that pose the greatest risk are rubber for birds, soft plastics and fishing debris for mammals, and hard and soft plastics for sea turtles, concludes this study published in PNAS.

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.

The cyanobacterium Prochlorococcus, the smallest and most abundant photosynthetic organism on Earth, is an important producer of oxygen and is crucial to marine ecosystems. A team from the United States has collected data from ships sailing the Pacific Ocean over a ten-year period and concluded that these cyanobacteria could experience population declines of between 17% and 51% in tropical oceans by the year 2100, depending on the warming scenario. The results, which are the product of modeling work, are published in the journal Nature Microbiology and indicate that this microorganism is more vulnerable to climate change than previously thought.

Most research on the presence of plastics in the seas has focused on macro- and microplastics. Now, an international team has analyzed the presence of nanoplastics - smaller in size - in different locations and depths of the North Atlantic Ocean, including areas near the European coasts. The results suggest that these may account for the majority fraction of the total mass of plastic in the oceans and that the total mass of marine plastic may be greater than previously thought. The work is published in the journal Nature. 

The Atlantic Ocean's main current system - the AMOC - could weaken without collapsing this century, according to modeling published in Nature. This finding contradicts earlier studies that predicted the collapse of the AMOC around 2050. The research uses models that include extreme changes in greenhouse gas concentrations and freshwater levels in the North Atlantic. This system of ocean currents is involved in regulating global temperatures.

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.

The fifth session of the United Nations Intergovernmental Negotiating Committee to develop an international legally binding instrument on plastic pollution (INC-5) ended without a treaty in Busan, South Korea, in the early hours of the morning. The more than 100 countries participating in what was to be the final round of negotiations have agreed to continue negotiating, reports Reuters.

A study published today in Science reveals a new plastic as durable as conventional plastics that decomposes in seawater. According to the authors, this new material could help reduce microplastic pollution accumulating in the oceans and eventually entering the food chain.