What is already happening?
  • UK seas show an overall warming trend. Over the past 30 years, warming has been most pronounced to the north of Scotland and in the North Sea, with sea-surface temperature increasing by up to 0.24°C per decade. 
  • Superimposed on this long-term warming trend are short-term variations. For example, UK shelf seas were warmer in 2000–2008 than 2009–2013, but recent years have seen warmer conditions return. 
  • UK sea-surface temperature in 2014 was the warmest on record (records go back to 1870), and eight of the ten warmest years have occurred since 2000. 

High evidence, high agreement

Sea-surface temperatures are one of the most-measured parameters in the ocean, as a result there are high levels of evidence. Although some of the observational records are shorter than others and have difference in sampling, they all offer a coherent picture of long-term and shorter-term variability, giving rise to a higher level of confidence in the results.

What could happen in the future?
  • Warming of UK shelf seas is projected to continue over the coming century. Most models suggest an increase of between 0.25°C and 0.4°C per decade. 
  • There may be some regional differences. For example, warming is expected to be greatest in the English Channel and North Sea, with smaller increases in the outer UK shelf regions.

Medium evidence, high agreement

There is high confidence in a continued rise in global SST, but our understanding of likely rates of warming at regional scales is lower.

Key Challenges and Emerging Issues
  • Improving understanding of the ocean scale influence on shelf-sea temperatures, including the causes and effects of change in the North Atlantic subpolar gyre. 
  • Producing more accurate SST predictions (monthly-seasonal; sub-decadal) and near future decadal and multi-decadal projections.
  • Conducting further research on the near-shore experience of marine heat wave conditions, and how these events could affect ecosystems, industry, and society.