Ocean Acidification

Ocean chemistry

The chemistry of the oceans is changing due to climate change, with approximately a quarter of the carbon dioxide released into the atmosphere being absorbed by the oceans. This CO2 dissolves in water, forming carbonic acid. Over the past 200 years, ocean acidity has increased by 30%, a phenomenon known as ocean acidification. The combined effects of rising sea temperatures and increased carbon dioxide levels pose a significant threat to marine biodiversity.

Coral reefs, especially branching corals, are highly sensitive to changes in ocean acidity, which weakens their structures and makes them more vulnerable to damage. Historically, monitoring acidity in oceans were challenging as boat measurements only provides localised data. However, advances in satellite and imaging technology has allowed global monetisation of ocean acidity. By combining data on salinity, chlorophyll levels, and sea surface temperature with machine learning, scientists can create global maps of ocean chemistry. Understanding these changes are essential for developing strategies to protect and restore coral reefs.

Global ocean acidification increase article

Global ocean acidification increase Credit ESA

The new ‘ocean pH stripes’ from a current ESA project visualise the change in ocean acidification as constructed from observations over the past 40 years. And this visualisation was used at the recent COP28 climate conference to highlight the plight of the ocean and the decline in ocean pH driven by greenhouse-gases emissions and climate change.”

Sentinel 2 captures coral bleaching — Images from the Copernicus Sentinel-2A satellite captured on 8 June 2016 and 23 February 2017 show coral turning bright white for Adelaide Reef, Central Great Barrier Reef. Credit ESA

Detecting coral bleaching — Sentinel-2A image of Grub and Corbett Reef, Great Barrier Reef, Australia. The change in seafloor reflectance is shown colour coded according to the legend. An increase in seafloor reflectance is caused by the seafloor exhibiting brighter albedo (reflectivity), which is what would be expected from coral bleaching. Credit ESA

Links to further information:

ESA – Satellites increasingly critical to monitor ocean health

SMOS/Space_is_key_to_monitoring_ocean_acidification