New report shows key indicators of Earth’s health are ‘outside the safe operating space’ as climate disaster looms

The Southern Ocean (SO) plays a pivotal role in the global carbon cycle by absorbing anthropogenic carbon dioxide (CO2). Yet, it remains uncertain whether this role will persist under future mitigatio...

Autotrophic carbon fixation, the conversion of inorganic carbon into biomass, underpins life on Earth. Prokaryotes can carry out this process via at least seven biochemically distinct pathways, yet the phylogenetic and environmental distribution of most remains poorly resolved. Screening approximately 40 billion genes from reference genomes, metagenome-assembled genomes (MAGs) and unbinned metagenomic contigs, we provide a global assessment of the phylogeny and ecophysiology of prokaryotic autotrophs. Most pathway marker genes occurred in unbinned contigs and low-quality MAGs, representing phylogenetically distinct lineages absent from isolate genomes and quality filtered MAGs. Established autotrophs accounted for the large majority of pathway detections in quality filtered MAGs, largely recapitulating known biology from cultivated model organisms. Against this backdrop, the reductive TriCarboxylic Acid (rTCA) cycle, long considered restricted to anoxic environments, was detected in three phylogenetically distinct Campylobacterota lineages from oxygenated surface seawater, suggesting a previously unrecognized and unexpected niche for this pathway. We show that all three MAGs share an enzyme variant, previously described in other oxygen-tolerant lineages, that likely underlies their presence in the oxygenated surface ocean. Read mapping across global ocean metagenomes indicates that the organisms carrying it could be far more widespread than the scarcity of recovered MAGs alone would suggest. Together, these findings illustrate that the current view of global autotrophic carbon fixation is largely shaped by what genome-resolved methods can readily recover, while the true phylogenetic and ecological distribution of autotrophic carbon fixation appears to be much broader. ### Competing Interest Statement The authors have declared no competing interest. Horizon Europe Programm, 101082304

Nature Reviews Earth & Environment, Published online: 03 September 2026; doi:10.1038/s43017-026-00825-8Fishing has long been a concern to ocean ecosystems, but it can also impact the carbon cycle by disturbing the biological carbon pump (BCP). This Comment discusses whether a ‘BCP fisheries code of practice’ could and should be developed to incentivize natural resource management mechanisms that protect the BCP.

Phytoplankton play a central role in marine ecosystems and the global carbon cycle.

Hidden inside tree trunks, between grains of soil, deep within our bodies, and below our feet, fungi seem to wind their way into everything. But did you know fungi actually live in the ocean, too? New research published in PLOS Biology reveals the overlooked role of marine fungi in the carbon cycle by zooming in on the seawater and sediments that line an Arctic fjord in Norway. We're only just starting to understand how widespread fungi are on this planet, and how much they contribute to the global carbon cycle. Marine fungi are easily overlooked because they're microscopic, but that doesn't mean their impact is small. For the first time, scientists quantified how much fungi in marine sediments are incorporating dissolved, free-floating amino acids into their bodies, trapping carbon and nitrogen. "Our study shows that fungi in the Arctic Ocean can contribute significantly to carbon storage in sediments via their highly efficient metabolism," explains geomicrobiologist William Orsi of Ludwig Maximilian University of Munich (LMU Munich) in Germany. "This is important because it is a previously unknown mechanism of microbial carbon storage in Arctic fjords, key geological settings that store more than 10 percent of all the carbon buried below the...

Ocean warming can influence both the quantity and composition of dissolved organic carbon released from large coastal macrophytes such as seagrasses and eelgrasses, according to analyses of cross-ecos...

High sea surface temperatures are expected to weaken ocean carbon sinks and damage coral reefs.

Southern Ocean Air Sea Fluxes of Heat and Carbon: coordination, opportunities, and technologies Air-sea fluxes of heat and carbon in the Southern Ocean are central to the ocean’s role in climate, yet ...

Carbon dioxide released into the atmosphere and absorbed by water lowers its pH level, making the ocean more acidic and less able to sustain life. In 2009 a group of scientists included this ocean aci...

The EU project SYNCHRONY will launch on August 1st, 2026. It aims to contribute to a better understanding of the rapid changes taking place in the complex system comprising the ocean, ice and atmosphe...

Studies regarding the role of bubbles on air-sea gas exchange over the past decades are reviewed Bubble-mediated gas transfer is strongly nonlinear, solubility-dependent, and asymmetric; its role...

Over 20 communities across Alaska are taking weekly water samples to develop baseline data on ocean acidification.

The global ocean apparently consumes more organic carbon than it produces. The excess heterotrophy probably occurs in the nearshore zone. This nearshore heterotrophy has significant implications with...

While most newly formed organic carbon in the dark ocean is derived from chemolithoautotrophic microorganisms, 17% also comes from an alternative pathway called anaplerosis that is related to the tric...

Locally, mangroves can sometimes adapt to rising seas, but global trends look troubling.

BIOPOLE is an interdisciplinary NERC programme examining biogeochemical processes and ecosystem function in polar ecosystems. BIOPOLE will address a fundamental aspect of the Earth System – how…

Post-2009, reduced sea ice in the Arctic led to a sharp decline in fixed-nitrogen concentrations, which may have been due to increased benthic denitrification on the Arctic shelves, according to obser...

Abstract. As the largest active carbon reservoir on Earth, the ocean is a cornerstone of the global carbon cycle, playing a pivotal role in modulating ocean health and the Earth's climate system. Unde...

The science made possible by satellites.

Here is a great resource for anyone working on ocean carbon: Jiang et al. (2026) compiled a comprehensive synthesis of data products for ocean carbonate chemistry — all in one place for you! The paper...

New data from remote floats around the world indicate the eddy subduction pump is of only secondary importance.

ESA science illuminates the ocean's role in the global carbon cycle and Earth system stability.

Chlorophyll-a (chl-a), as the dominant photosynthetic pigment within phytoplankton, provides an indication of the phytoplankton biomass and are essential for understanding global and regional changes ...

Gas transfer velocities (k) in the coastal Baltic Sea are lower than in other ocean regions at the same wind speeds The lower k is attributed to wind fetch limitation, wind-wave interactions, and...

A study in Nature Geoscience reveals that changes in the West Antarctic Ice Sheet (WAIS) closely tracked marine algae growth in the Southern Ocean over previous glacial cycles, but not in the way scientists expected.

As seawater becomes steadily more acidic, complex branching corals die off and are replaced with hard boulder corals and algae.