Climate change impact on oceans 

Scientists say the seas have absorbed 90% of all the warming that has taken place in the past 50 years.

The ocean is inextricably linked to our climate. Rising air temperatures due to global warming are melting the polar ice caps and dissolving glaciers, leading to rising sea levels.

But the ocean is also playing a crucial role in protecting us from the worst effects of climate change. Scientists say the seas have absorbed 90% of all the warming that has taken place in the past 50 years.

Sea levels on the rise

The Intergovernmental Panel on Climate Change (IPCC) says that by 2100, sea levels will be between 0.26 metre and 0.77 metres higher than today. It’s estimated that by 2100, rising sea levels will threaten 200 million people who live in low-lying coastal areas.

Researchers say that almost half of the world’s sandy beaches could disappear as sea levels rise. It’s estimated that by 2050, more than 570 cities will be affected by a sea level rise of 0.5 metres.

Warming seas

The IPCC also estimates that even if the rise in global air temperatures can be held to 1.5°C, sea temperatures will rise by at least 2 °C by the end of the century.

Rising sea temperatures are to blame for “coral bleaching”. When the water is too warm the corals expel the algae living in their tissues and turn white. Scientists say that coral can recover from bleaching events but it is permanently weakened.

Our changing waters

Meanwhile, melting freshwater from the world’s polar ice sheets changes the chemical composition of the sea making it hard for some species to survive. A study of the Baltic Sea warned that reducing salinity could threaten zooplankton, the tiny creatures who represent the foundation of the marine food chain.

Freshwater also changes ocean currents and if these fail or change course it can lead to oxygen-depleted “dead zones” where marine animals and plants cannot survive.

The oceans are our biggest carbon sink, absorbing around one-third of the CO2 emitted by human activity since the start of the Industrial Revolution.

Coral research is making waves

Conservationists and community groups are taking action to restore their coral reefs. In Jamaica, which lost 85% of its coral to hurricanes and pollution, “coral gardeners” are nurturing young corals.

• The ocean is a massive carbon sink, protecting us from the worst of climate change.
• But rising air temperatures are melting glaciers, while warming seas are bleaching coral.
• Action like coral reef restoration is already underway – and research has found some corals to be more resistant to higher temperatures.
• And there are now calls to designate Marine Protected Areas for 30% of the ocean by 2030.
  

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