Impact of climate change on the marine environment

The Marine Climate Impacts Partnership has published its latest annual report card. The report card aims to address/summarise the following:

• What is the current state of scientific understanding of marine climate change in our oceans and seas?
• What changes have been observed and what could happen in the future?
• How much of this is hard fact and how much is interpretation?

A few key observations are as follows:

• 2006 was the second warmest year for UK coastal waters since records began in 1870; with seven of the 10 warmest years in the last decade.
• Warmer winters have been strongly linked to reduced breeding success and survival in some seabird populations.
  Models predict fewer storms in future but there will be increased numbers of severe storms.
• Coastal erosion and flooding is expected to increase.
• The impacts of climate change on the commercial services provided by our seas will be significant. Sea-level rise, coastal flooding, storms and bigger waves will affect ports, shipping and built structures. Fishing and fish farming will be affected by temperature change and plankton (prey) availability.

Specifically on fish:The impact of climate change on commercial and other fish stocks is not yet clear but may be influenced by temperature rises, increased ocean acidity (due to more CO₂ dissolved in water). Observations of trends to date state with medium confidence that excessive fishing pressure over many decades may have resulted in fish populations less able to ‘buffer’ against occasional poor year classes and the impacts of natural climate variability. Distribution shifts and modifications of fish behaviour as a result of temperature changes, may be affecting the vulnerability of certain fish stocks to fishing fleets.

As for the future it is possible to state this (with medium confidence): In the short term, climate change will have little influence on fish stock recovery, which depends instead upon reducing fishing effort to allow existing year classes to survive to maturity. Long-term climate change may affect the overall productivity of fish stocks in a given area. Some species may be adversely affected leading to reductions in sustainable yield whilst others, for example seabass, red mullet and John Dory, may be positively affected leading to enhanced fishing opportunities.