Global Warming
A fisherman holds a fish caught in his net in the waters of Guanabara Bay in Rio de Janeiro Brazil, January 8, 2016. Reuters/Ricardo Moraes

Climate change is affecting the planet in numerous ways. While Australia’s Great Barrier Reef and few other reefs in the world are experiencing massive coral bleaching due to rising ocean temperatures, scientists have found that oxygen levels in oceans are also decreasing steadily. This could well be one of the most serious side effects of global warming.

A study published in the American Geophysical Union's journal Global Biogeochemical Cycles discusses the effects of depleting oxygen levels in world oceans. Marine life is under serious threat, as lower oxygen levels could cause other devastating trends for wildlife such as oceans turning acidic.

“We're driving pretty massive changes in the environment - and we're not just changing one variable. We're changing a suite of variables to which marine organisms are sensitive, and basically putting significant demands on their adaptive capacities,” Matthew Long, lead author of the study and scientist at US's National Centre for Atmospheric Research, told Fairfax Media.

Earth’s oceans have become 30 percent more acidic as a result of absorption of billions of tonnes of carbon dioxide released from burning fossil fuels and forests every year. Now that oxygen levels in the seas are falling at an alarming rate, widespread evidence of the trend will be evident 2030 onward.

“Oxygen is a necessary ingredient for marine life, for all sorts of marine organisms. The extent we care about marine ecosystems for their intrinsic value, we should care. We're also reliant on these systems for food - fisheries will be vulnerable,” Long added.

The study says south-east Asia, eastern Africa and eastern Australia may be spared till the next century, but the process is already underway in eastern tropical Atlantic and Pacific oceans and southern Indian Ocean.

Warming seas absorb less oxygen at the surface. Moreover, due to climate change, oceans turn over less. Hence, oxygen does not move deeper. Long has thus questioned Australia's CSIRO’s decision to cut climate modelling and monitoring programs. According to him, it is important for governments to invest in consistent and long-term research to predict and manage the impacts of deoxygenation.