Mers et océans

Global sea level rose faster than expected in 2024, mostly because of ocean water expanding as it warms, or thermal expansion. According to a NASA-led analysis, last year’s rate of rise was 0.23 inches (0.59 centimeters) per year, compared to the expected rate of 0.17 inches (0.43 centimeters) per year.

The Atlantic Meridional Overturning Circulation (AMOC), vital for northwards heat transport in the Atlantic Ocean, is projected to weaken owing to global warming1, with significant global climate impacts2. However, the extent of AMOC weakening is uncertain with wide variation a …

... An “acid” test of our interpretation will be provided by the 2025 global temperature: unlike the 1997-98 and 2015-16 El Ninos, which were followed by global cooling of more than 0.3°C and 0.2°C, respectively, we expect global temperature in 2025 to remain near or above the 1.5°C level. Indeed, the 2025 might even set a new record despite the present weak La Nina. There are two independent reasons. First, the “new” climate forcing due to reduction of sulfate aerosols over the ocean remains in place, and, second, high climate sensitivity (~4.5°C for doubled CO2) implies that the warming from recently added forcings is still growing significantly.

Human-driven ocean warming is increasingly overwhelming El Niño, La Niña, and other natural climate patterns.

Some scientists fear the risk of a collapse to warm Atlantic currents has not been taken seriously.

To date, the ocean has largely been treated as an afterthought in global climate strategies, sidelined in favor of more visible priorities like renewable energy and reducing carbon emissions. But ocean-based solutions are indispensable to the green transition and must be funded accordingly.

Visualize and download global and local sea level projections from the Intergovernmental Panel on Climate Change Sixth Assessment Report.

The Atlantic Meridional Overturning Circulation is the main driver of northward heat transport in the Atlantic Ocean today, setting global climate patterns. Whether global warming has affected the strength of this overturning circulation over the past century is still debated: observational studies suggest that there has been persistent weakening since the mid-twentieth century, whereas climate models systematically simulate a stable circulation. Here, using Earth system and eddy-permitting coupled ocean–sea-ice models, we show that a freshening of the subarctic Atlantic Ocean and weakening of the overturning circulation increase the temperature and salinity of the South Atlantic on a decadal timescale through the propagation of Kelvin and Rossby waves. We also show that accounting for upper-end meltwater input in historical simulations significantly improves the data–model agreement on past changes in the Atlantic Meridional Overturning Circulation, yielding a slowdown of 0.46 sverdrups per decade since 1950

The idea that the AMOC is headed to collapse is very controversial, but it is clearly weakening. If the circulation did collapse, the consequences on both sides of the Atlantic Ocean would be immense—including large changes in temperature and a spike in weather-related disasters.

The Atlantic Ocean's most vital ocean current is showing troubling signs of reaching a disastrous tipping point. Oceanographer Stefan Rahmstorf tells Live Science what the impacts could be.

The network of Atlantic ocean currents keeping the Earth's climate stable are far closer to collapse than first estimated, scientists warn.

AMOC collapse would bring severe global climate repercussions, with Europe bearing the brunt of the consequences.

Oceanographer Stefan Rahmstorf explains why Amoc breakdown could be catastrophic for both humans and marine life

International lawyer challenging dangerous deep water petroleum production offshore Guyana

The sudden collapse of carbon sinks was not factored into climate models – and could rapidly accelerate global heating

In an interview from jail in Greenland with the AFP news agency, the anti-whaling activist said Tokyo has a vendetta against him.

The story of Greenland keeps getting greener—and scarier. A new study provides the first direct evidence that the center—not just the edges—of Greenland's ice sheet melted away in the recent geological past and the now-ice-covered island was then home to a green, tundra landscape.

There is increasing concern that the Atlantic Meridional Overturning Circulation (AMOC) may collapse this century with a disrupting societal impact on large parts of the world. Preliminary estimates of the probability of such an AMOC collapse have so far been based on conceptual models and statistical analyses of proxy data. Here, we provide observationally based estimates of such probabilities from reanalysis data. We first identify optimal observation regions of an AMOC collapse from a recent global climate model simulation. Salinity data near the southern boundary of the Atlantic turn out to be optimal to provide estimates of the time of the AMOC collapse in this model. Based on the reanalysis products, we next determine probability density functions of the AMOC collapse time. The collapse time is estimated between 2037-2064 (10-90% CI) with a mean of 2050 and the probability of an AMOC collapse before the year 2050 is estimated to be 59±17%.

A new study suggests that the Gulf Stream was stronger during the last ice age due to more powerful winds, indicating that future changes in wind patterns could weaken the Gulf Stream, affecting European climate and North American sea levels. This research enhances our understanding of the Atlantic Meridional Overturning Circulation (AMOC) and its vulnerability to climate change.

Warning after intensification of storm aided by unusually hot ocean waters in much of Beryl’s path. Hurricane Beryl, which slammed into Texas on Monday after wreaking havoc in the Caribbean, was supercharged by “absolutely crazy” ocean temperatures that are likely to fuel further violent storms in the coming months, scientists have warned.