Satellites reveal how oceans absorb carbon in unprecedented detail

The world’s seas have long acted as a planetary safety net, soaking up excess heat and roughly a quarter of all human-generated carbon dioxide.

Yet this crucial buffer is anything but uniform. Some waters capture carbon, others release it, and the balance can swing in a matter of days.

Until now, most global maps blurred those variations into month-long snapshots at coarse, 100-kilometer grids.

A new satellite-driven product called OceanSODA-ETHZ changes that picture, offering eight-day updates at 25-kilometer resolution and revealing the ocean carbon sink in unprecedented detail.

Satellites fill ocean carbon gaps

Direct readings of surface-water CO2 come from ships and buoys, leaving vast gaps in space and time.

“Increasing the resolution of these global datasets is challenging because the number of direct measurements of carbon dioxide at the ocean’s surface is rather sparse across all regions and times,” explained project co-leader Nicolas Gruber of ETH Zurich.

To fill those gaps, Gruber’s team paired the in situ data with a suite of Earth-observation satellites that sense sea-surface temperature, color, wind, and more – variables tightly linked to how much CO2 water can hold.

Feeding that information into a cascade of machine-learning algorithms produced a fine-grained, eight-day global mosaic.

“This new version maps the parameters of the ocean carbon system every eight days at a resolution of about 25 by 25 kilometers, more than 30 times finer than previous products,” Gruber said.

“A critical part of the approach is the use of satellite data, which provides detailed information to interpolate the measurements in time and space.”

Satellites track ocean carbon changes

Presented this week at ESA’s Living Planet Symposium, the dataset already highlights dramatic short-term swings.

An animation released by the team tracks the 2017 Atlantic hurricane season, when storms such as Maria and Irma churned deep, carbon-rich waters to the surface.

In the visualization, red plumes – areas where the sea outgasses CO2 – flare beneath the swirling wind arrows, then fade as cooler, oxygen-laden surface layers return.

Jamie Shutler from the University of Exeter, while not involved in developing the product, is already using it for storm studies.

“Thanks to its fine detail, the dataset can help us separate and understand the influence of events like hurricanes – where deep water, often high in carbon, can be forced to rise to the surface – which can cause sudden spikes or changes in surface ocean carbon dioxide levels,” said Shutler.

A new view of ocean acidification

Every molecule of CO2 that the ocean absorbs reacts with seawater, lowering pH and shifting carbonate chemistry in ways that erode coral skeletons, thin oyster shells, and alter plankton communities.

Until now, researchers tracking this “other CO2 problem” relied on sparse records or coarse climatologies.

OceanSODA-ETHZ delivers near-real-time fields of surface pH and carbonate ions, letting scientists watch acidification pulses unfold as upwelling, rainfall, or melting sea ice change local chemistry.

Because the product also extends back to 1985, analysts can mine four decades of fine-scale variability to see where buffers are weakening and hotspots are emerging.

Those insights can feed into fisheries management, coastal planning, and global carbon-budget assessments.

ESA powers new ocean maps

The dataset is the latest deliverable from ESA’s FutureEO “Science for Society” program, which funds innovative uses of satellite records.

“The fact that we can use this method to gain new insights into the exchange of carbon dioxide between the ocean and atmosphere – and on the ocean acidification altogether – is a great step forward in ocean science,” said Roberto Sabia, an ocean scientist at ESA Earth-Observation.

Gruber and colleagues emphasize that OceanSODA-ETHZ is not a static atlas but a living product that can assimilate new ship measurements and leverage upcoming satellite missions.

Higher-resolution sensors such as NASA’s PACE and ESA’s Copernicus Expansion promise even clearer views of plankton blooms, sea-surface roughness, and dissolved organic matter – all factors that modulate carbon exchange.

Forecasts of regional carbon uptake

Ultimately, the goal is to couple these detailed maps with ocean-atmosphere models, yielding short-term forecasts of regional carbon uptake akin to daily weather predictions.

Such tools could alert coastal managers when acidification thresholds are likely to be breached or help negotiators refine national emissions budgets by tracking natural carbon sinks more precisely.

For now, the new product already reshapes our understanding of the ocean’s role in moderating climate.

Where earlier charts smoothed over crucial dynamics, OceanSODA-ETHZ reveals a living, breathing carbon landscape – one where swirling eddies, roaring storms, and shifting currents all leave their stamp on the planet’s most important carbon reservoir.

Image Credit: ESA

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–