The over-riding threat to our marine environment is the risk posed by climate change. The Intergovernmental Panel on Climate Change (IPCC) reports that global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. The UK Met Office's State of UK Climate Report series sets out the latest evidence and climate change trends that are being seen around the UK. The 2020 report noted that it was the third warmest year for the UK in a series since 1884 and the fifth wettest year in a series that has been running since 1862.
Marine environmental conditions
As 90% of the world’s global warming has been absorbed by the oceans, it is unsurprising that we are also seeing effects on the environmental conditions of our marine environment. The 2020 State of UK Climate Report highlights that it was the eighth warmest year on record in the UK, in a series that runs from 1870, for near coastal-sea-surface-temperatures and that sea leve rise is now at 3mm per year. Since the start of the 20th Century sea level rise is reported to have risen by 16.5cm. The overall effects on our marine environment include:
- A rise in mean sea temperatures
- A rise in sea levels
- An increase in sea water acidity (acidification)
- A decrease in the amount of oxygen available (deoxygenation)
- A pattern of increased frequency and intensity of weather extremes
- Loss of ‘climate space’ where conditions are suitable for species
- Increase in the conditions suitable for invasive non-native species
Consequences for marine wildlife
There are a wide range of effects on our marine habitats, wildlife and seabirds from these climatic changes. For example, acidification affects the ability of mollusc species, such as mussels and oysters, to develop their protective shells by reducing the process of calcification.
A pattern of increases in sea temperatures and intensity of storms have both indirect effects on our internationally important breeding seabirds through reductions in food availability and direct effects such as increases in the mortality of birds during extreme weather. For example, black-legged kittiwake, have declined by 70% since the mid-1980s, with the downward trend largely linked to a reduction in their main food supply, sandeels, as result of climate change.