Study shows changes in climate regime & redistribution of biodiversity in Bay of Biscay


A report drawn up by AZTI and Naturklima shows that the effects of climate change on coastal areas, including the global warming of the oceans, extreme wave events and increases in the rate of sea-level rise are being felt on the Basque coast, and alerts to changes in the climate regime and a redistribution of biodiversity in the Bay of Biscay.

The study has been conducted with the support of the LIFE Integrated Urban Klima 2050 project and published in the specialist journal Science of the Total Environment. Its goal was to analyse time series of climate change indicators in the Bay of Biscay, including the Basque coast. An integrated, flexible method based on generalised additive mixed models was used to detect trends in 19 indicators (including marine physics, chemistry, the atmosphere, hydrology, geo-morphology, biodiversity and commercial species). Over half a million observations were taken from 87 time series analysed over the past 40 years. The results show four climate change regime groups:

  1. A gradual change associated with climate change since the 80s can be seen, with increases in sea temperature on the surface and to depths of 100m in the bay (0.10 - 0.25ºC every ten years) and increases in air temperature and sunlight. This warming may have had a knock-on effect in redistributing benthic communities on the Basque coast, favouring warm-water species over cold-water species. The weight-at-age of anchovies and sardines has also decreased in the past 20 years.
  2. The mixed winter layer in the south-eastern part of the bay is now deeper, which has probably led to an increase in nutrients, in surface oxygen and in chlorophyll concentrations.
  3. There is a rise in sea levels (1.5 - 3.5 cm every 10 years since the 90s) associated with climate change.
  4. There has been a 16.8 cm increase per 10 years in the height of extreme wave events, probably related to the storms of the past ten years, which is impacting erosion on beaches.

Studies such as this one help to draw up an accurate estimate of the rates of increase in sea temperature, sea levels and extreme phenomena, and to forecast future paths for marine productivity. These are fundamental indicators in determining the best ways to adapt and minimise the negative impacts of climate change in the region.