Researchers from the Spanish Institute of Oceanography (IEO) in the Balearics are to lead a project to analyse deep water in the western Mediterranean and specifically an anomaly in the temperature and salinity that arose in the harsh winter of 2005 and which still influences the sea's circulation and climate.

The IEO says that during that winter there were five episodes when Arctic and Siberian winds brought about significant snowfalls in the whole of the western Mediterranean. Its scientists have detected the persistence of the anomaly and its impact on the western basin.

In 2009 at a international meeting for the scientific study of the Mediterranean in Malta, it was proposed calling this phenomenon the "Western Mediterranean Transition", following on from an anomaly that had previously been observed in the eastern Mediterranean.

According to scientists, the Mediterranean acts in providing a continuous source of intermediate and warm saline water - the Mediterranean Outflow Water - that plays an important role in the process of deep water formation in the northern Atlantic and, therefore, circulation of global ocean. It has also been shown that hydrographic phenomena that generate deep water masses affect biological processes and so marine life.

The IEO says that there is no agreement as to the relative importance of the different mechanisms of deep water formation that have contributed to this phenomenon. It does seem to be the case that anomalies observed in both the eastern and western basin are the result of factors such as the increased level of salinity in the Mediterranean, probably brought about by climatic oscillation and, indirectly, by climate change.

The headquarters of the Balearic Oceanography Centre at the IEO hosted the first meeting at the end of January to co-ordinate the project of studying the anomaly. This was attended by researchers from various centres, such as in Malaga and Barcelona, as well as from the Aemet meteorology agency. The study is to be funded under the state plan for scientific and technical research and development and it will run from this year until 2018.