Winter sea temperatures around Iceland have reached the highest levels ever recorded during long-term monitoring, according to new measurements from a research cruise that ended on 17 February. Scientists found unusually warm water in the upper ocean during the annual winter survey.
The survey was carried out by the Icelandic research vessel Þórunn Þórðardóttir during a 15-day expedition. The mission monitored ocean conditions around Iceland as part of a long-running programme that has taken place three to four times each year since 1970.
Extensive measurements across Icelandic waters
Researchers measured temperature and salinity along 10 survey lines extending from the coast. In total, they collected data at about 100 stations.
At each station, scientists measured conditions throughout the water column. Samples were also taken at different depths to analyse nutrients, oxygen and other key indicators of ocean health.
New instruments also recorded current speed and direction down to 1,000 metres along the ship’s route.
Record temperatures in Atlantic waters
Water in the upper 200 metres was generally warmer than the long-term average. At many stations, the temperature was the highest recorded during winter surveys since the programme began in 1970.
In Atlantic waters south and west of Iceland, a record temperature of 8.55°C was measured at station Selvogsbanki 5. Near-record values were also recorded at Stokksnes 4, with a temperature of 8.8°C and salinity of 35.28.
North of Iceland, the temperature at the station Siglunes 4 reached 5.0°C, another record for the winter survey. Warm Atlantic water also extended eastward beneath the surface to Langanes.
Long-term warming trend observed
Scientists say ocean temperatures have generally risen since 1970, despite large year-to-year variations.
The warm conditions south of Iceland suggest Atlantic water has strengthened again after a period of cooler conditions that reached a low point in 2017.
Researchers say more study is needed to understand how such warm periods may affect deep ocean circulation and climate patterns in the North Atlantic.