How is climate change affecting the oceans?

coral reef
Image: Colourbox/FAU

IPCC info bites

Emissions of greenhouse gases like carbon dioxide from human activity cause ocean warming, acidification, oxygen loss, and other physical and chemical changes that are affecting marine ecosystems around the world. At the same time, natural climate variability and direct human impacts, such as overfishing and pollution, also affect marine ecosystems locally, regionally and globally. These climatic and non-climatic factors mutually reinforce each other.

Tipping points – a threshold beyond which an abrupt or rapid change in a system occurs – that have already been reached in ocean systems include the melting of sea ice in the Arctic, thermal bleaching of tropical coral reefs and the loss of kelp forests.

To prove that the oceans are changing because of human-induced climate change, scientists use various methods. With the help of paleo records, they reconstruct connections between climate, evolutionary and ecological changes in the geological past; with experiments, they investigate current climatic and ecological reactions, for example to higher CO2 levels in the water, or test in models what relative influence certain factors have.

Why are biodiversity hotspots important?

Bild: Colourbox/FAU

Biodiversity hotspots are ecologically unique regions that are exceptionally rich in species, and are thus priority targets for nature conservation. There are many definitions of biodiversity. All of them include the variation within and between species and of ecosystems and identify a set of priority areas that cover a small portion of the Earth, but house an exceptionally high proportion of its biodiversity.

IPCC Report info bites


The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change. In their latest report, published in late February, scientists outline the state of scientific, technical and socio-economic knowledge on climate change, its impacts and future risks, and options for reducing the rate at which climate change is taking place. One of the report’s main authors is Prof. Dr. Wolfgang Kiessling, head of the Chair of Palaeontology at FAU.

Wolfgang Kießling on the World Climate Report