The Baltic dead zone

Concern at the turn of the century over the growing lack of oxygen in the Baltic Sea and parts of the North Sea led to a conference of concerned nations. In 2007, they agreed on measures to reduce factors such as effluent which deplete marine oxygen. However, it seems that global warming is counteracting these measures, as the Leibniz Institute for Baltic Sea Research reports:

The Baltic Sea is a marginal sea in northern Europe with the world’s largest area of oxygen-depleted, thus, dead sea bottoms. The size of this area now roughly covers the area of the Republic of Ireland. This situation is caused by the consumption of oxygen during the decomposition of dead organic material from plankton blooms. During the past decades such blooms were fueled in excess by nutrient (nitrogen and phosphorus) loads from the land. With growing population and the subsequent intensification of the agriculture, especially since the Second World War, there has been a rapid increase in nutrient supply into the Baltic Sea. Although this trend has reversed since the 1980s, for example through the expansion of sewage treatment plants and reduced fertilizer consumption, the extent of the dead sea bottoms is still very large.

In order to improve the environmental status of the Baltic Sea, its riparian countries signed in 2007 under the auspices of the Helsinki Commission (HELCOM) the so called Baltic Sea Action Plan (BSAP). They jointly agreed upon measures to reduce nutrient loads. However, results are not yet visible and due to the slow response time of the Baltic Sea, it will still take some time. To make matters worse, the global climate warming may partly counteract the measures. This effect was not considered in the original version of the BSAP completely ignoring the growing scientific evidence of climate change. 

Predictive models are being updated. The results from running these will be published and hopefully will inform stakeholders of how earlier preventative measures are working and suggest what more, if anything, needs to be done.