The eastern tropical Pacific Ocean is known for its large low-oxygen zones that are increasing in size, putting marine life at risk. New research shows that 15 million years ago, the opposite was true. A Michigan State University study found that oxygen-deficient waters were distributed very differently during the mid-Miocene Epoch than they are today. The Pacific Ocean’s oxygen-deficient zones were much smaller, while the Atlantic’s were much larger. Scientists had never documented this reversal before. A computer model helped explain why. By recreating ancient ocean conditions, Associate Professor Dalton Hardisty’steam learned that a channel between North and South America allowed water to move freely between the Pacific and Atlantic oceans, reshaping ocean circulation and changing where low-oxygen waters formed.

Mindelo (São Vicente). For five years now, a distinctive green laser beam has been shining at night up to 30 km above the harbour of the island’s capital. It forms part of a high-energy lidar with which the Leibniz Institute for Atmospheric Research (TROPOS) operates continuous aerosol and cloud measurements at the Ocean Science Centre Mindelo (OSCM).

The lidar is part of PollyNET, a global network of fixed and mobile lidar systems coordinated by TROPOS. This network enables the detection of airborne particles (aerosols) – such as desert dust, forest fire smoke, industrial pollution or even sea salt – as well as their trajectories across our planet. The remote sensing station in Mindelo complements the dust samples that have been collected of the island of São Vicente for almost 30 years in Calhau on the north-east coast.

In recent years, marine heatwaves have been taking an ever-greater toll on the world’s oceans and their ecosystems. Amplified by increasing global warming, these events are occurring more frequently and lasting longer. The Arctic is not spared from this trend either, as it is warming faster than any other region on our planet. However, due to local processes and conditions, marine heatwaves in the Arctic differ fundamentally from those in non-polar oceans. A recent study, led by the Alfred Wegener Institute, in the journal Communications Earth & Environment, summarizes how these events have developed over recent decades, what science knows about the driving forces behind them, and where there are still knowledge gaps to be filled. 

In a new study scientists reveal up to 38-fold higher DMSP concentrations in Southern Ocean sea-ice versus the surrounding seawaters during the Southern Ocean austral winter. DMSP is known for protecting organisms against environmental stressors. Its degradation yields dimethylsulfide (DMS) and methanethiol (MeSH) which are important climate-cooling gases. The study underscores the role of this seemingly uninhabitable environment as a dynamic reservoir and transformation hub influencing climate-cooling cycles in the polar region.