Cape Town – A combination of ocean warming and overfishing continues to reduce fish numbers, while marine creatures are shifting their ranges at a rate of over 5km a year.
This was revealed in the Intergovernmental Panel on Climate Change (IPCC), the world’s most authoritative climate science body, which released its latest special report yesterday, examining how climate change is affecting the ocean and cryosphere - the frozen parts of the planet such as ice caps, glaciers, permafrost, shelf ice and snow.
The IPCC report points to some potentially irreversible changes and growing threats to the Earth’s oceans and shrinking cryosphere.
This comes as Arctic sea ice levels reached their second lowest level on satellite record - some 2.1 million Km2 below the average long-term minimum area.
The report, which assessed nearly 7 000 scientific papers, with input from 104 authors and editors from 36 countries and which was approved by 195 governments, found that the Earth’s ocean, ice and snow are changing at an accelerating rate due to greenhouse gas emissions.
Key findings include that sea-level rise is accelerating and without emission cuts the ocean will rise more than 10 times faster by 2100 than it did during the 20th century, and that glaciers will lose more than a third of their mass on average with high emissions, cutting water supplies to people who depend on them; some mountain ranges could lose more than 80% of their glaciers by 2100 and many glaciers will disappear entirely.
The Greenland and Antarctic Ice Sheets are melting, releasing more than 400 billion tonnes of water a year while the area of the Arctic covered by snow each summer is shrinking more than 13% a decade.
The overwhelming majority of marine heatwaves, 84%-90%, has also been attributed to human-caused climate change.
The total mass of animals in the world’s ocean could decrease by 15% and the maximum catch potential of fisheries could fall by up to 24% by the end of the century.
Coral is at particular risk as marine heatwaves are already causing more large-scale coral bleaching, and almost all warm-water coral will suffer significant losses and local extinctions, even with rapid emission cuts that limit warming to 1.5°C.
Other calcifying animals like barnacles and mussels are also threatened, the report found.
Greenpeace Africa, climate and energy campaigner Bukelwa Nzimande said: “There is no debate and the science is crystal clear: our reliance on coal means that our air is toxic, greenhouse gases are out of control, and we are killing our oceans.
"We need acts of unprecedented political courage from our leaders to prevent the most severe consequences for our planet by staying below 1.5ºC.”