Coccolithophores are tiny oceanic algae that produce calcium carbonate, which can help organic matter sink and affect the oxygen levels below. As ocean conditions change, we studied how these algae contribute to carbon transport in a low-oxygen, low-pH region of the Southeast Pacific. Our results show they survive in these challenging conditions, but their impact is lower than in most regions, suggesting that other phytoplankton may play a bigger role in moving organic carbon here.

Nitrate pollution from farming is a global problem. A natural process called denitrification helps remove nitrate but also releases CO₂, which contributes to climate change. Our study shows that CO₂ from this process in Danish groundwater may be a major overlooked source – similar to other known agricultural CO₂ emissions. This highlights the need to update greenhouse gas reporting to better reflect farming’s full climate impact.