Significant increase in dead zones in the world’s oceans

Humans discharge tons of nitrogen and phosphorus into the oceans – this can have serious consequences for the underwater world. UN chief Guterres is sounding the alarm.

According to a United Nations (UN) report, the number of so-called death zones in the world’s oceans has increased significantly. These are areas of very low oxygen moreIn which life is hardly possible. According to the United Nations’ second “World Ocean Assessment” on the state of the sea, the number of these areas increased from 400 to nearly 700 between 2008 and 2019, which was presented in New York on Wednesday. In addition, they are particularly affected Gulf of Mexico And the South China Sea also the Baltic and the North Seas.

The phenomenon occurs naturally in some marine areas. There is a reason algul blooms. After dying, the algae slowly sink to the bottom and are broken down by bacteria that consume oxygen. In this way, vast areas can form at depths, with many times containing hardly any oxygen in the water. The entry of nutrients like nitrogen and phosphorus into the oceans makes such algal blooms.

Increasing water temperature has a negative effect

a The report noted the situation and worsening trend: “It is estimated that man-made nitrogen input on the coasts will double in the first half of the 21st century.” In addition, through Climate change Also growing water temperature A negative effect.

United Nations Secretary-General Antonio Guterres The report called the findings “dangerous”: “The stresses caused by many human activities continue to stress them Of the oceanDestroying critical habitats – such as mangrove forests and coral reefs – and hamper their ability to cope with the effects of climate change, “he said. Guterres emphasized the role of CO2 emissions that cause oceans and rising water levels Destroy biodiversity in coastal parts. Will be threatened.

Meanwhile, the United Nations sees a positive development in the number of incidents involving ships. Accidents on the world’s oceans have decreased significantly in recent years. From 2014 to 2018, an average of 88 ships were “lost” each year, compared to an average of 120 in the last five years. There has also been progress in reducing air pollution from ship emissions. In addition, incidents with oil spills are still rare.