A new report on Biological Responses to Ocean Warming concludes with “high confidence that warming has strongly affected marine biodiversity and commercial fisheries over the last 50 years”. The report published in August 2017 was commissioned by the UK Government Office for Science. It is based on an extensive review of evidence from global scientific studies on how warming seas have already influenced marine organisms. The evidence of the impact of changing sea temperatures on marine life is summarised with a focus on the UK fisheries and aquaculture industries, and environmental conservation in UK territory and the UK’s overseas marine protected areas which include South Georgia and the Falkland Islands in the South Atlantic Ocean, the Chagos Archipelago in the Indian Ocean and the Pitcairn Islands in the Pacific Ocean.
Based on UK government data (UK Met Service and the Hadley Centre Global Sea Ice and Sea Surface Temperature dataset) sea surface temperature records have risen by 0.7°C from pre-industrial times (1870–1899) to the recent past (2005–2014). The report states that “importantly, sea temperature change has not been spatially consistent over a global scale”. Evidence of this across the UK’s overseas territories show that while there have been relatively low rises of sea surface temperatures of 0.2°C and 0.4°C in South Georgia and the Falkland Islands respectively, in the waters around the UK itself mean annual sea temperatures have risen by 0.8°C since 1870.
Other factors affecting marine life covered in the report include dissolved oxygen and sea-ice extent. Warmer waters carry less dissolved oxygen which can affect the growth and survivorship of fish due to low oxygen availability. Sea-ice extent changed significantly between 1979 and 2013 with mean annual Arctic sea-ice extent declined by 1.5 million km2 in contrast to the Antarctic sea-ice which increased by 0.8 million km2. The report notes that Antarctic sea-ice expansion is a result of increasing freshwater input from melting continental ice shelves.
Biological Responses to Ocean Warming Genner et al. August 2017 UK Government Office for Science