The seas have less oxygen now

The seas have less oxygen now

Part of: GS Prelims and GS Mains III–Environment Conservation

In News

• According to the study released by IUCN at Madrid Climate conference, the levels of oxygen in oceans fell by around 2 per cent from 1960 to 2010. Also, the water in some parts of the tropics had experienced a 40 per cent to 50 per cent reduction in oxygen.
• The deoxygenation of the oceans occurred due to climate change and other human activities (such as the nutrient runoff from farm fertilizers into waterways)
• The loss of oxygen in the oceans can affect the planetary cycling of elements such as nitrogen and phosphorous which are essential for life on Earth
• As oceans lose oxygen, they become more acidic, a phenomenon that has resulted in some places in shellfish having their shells degraded or dissolved — the so called “osteoporosis of the sea”.
• In many parts of the world,fish have been dying en masse — a clear illustration of the ways in which deoxygenation is choking the oceans.
• Apart from their declining oxygen content, oceans have, since the middle of the 20th century, absorbed 93 per cent of the heat associated with human-caused greenhouse gas emissions, leading to mass bleaching of coral reefs.