Ocean acidification effects on marine life. (Photo: UK Ocean Acidification Research Programme Knowledge Exchange)
IUCN report reveals impacts of ocean acidification on fish
Wednesday, September 07, 2016, 00:40 (GMT + 9)
The International Union for Conservation of Nature (IUCN) presented a comprehensive review on the impacts of ocean warming on fish stocks and crop yields, more extreme weather events and increased risk from water-borne diseases.
The report, Explaining ocean warming: Causes, scale, effects and consequences, reviews the effects of ocean warming on species, ecosystems and on the benefits oceans provide to humans.
Compiled by 80 scientists from 12 countries, the document highlights detectable scientific evidence of impacts on marine life, from microorganisms to mammals, which are likely to increase significantly even under a low emissions scenario.
"Ocean warming is one of this generation's greatest hidden challenges - and one for which we are completely unprepared," pointed out IUCN Director General Inger Andersen.
"The only way to preserve the rich diversity of marine life, and to safeguard the protection and resources the ocean provides us with, is to cut greenhouse gas emissions rapidly and substantially," Andersen stated.
Ocean warming is already affecting ecosystems from polar to tropical regions, driving entire groups of species such as plankton, jellyfish, turtles and seabirds up to 10 degrees of latitude towards the poles, causing the loss of breeding grounds for turtles and seabirds, and affecting the breeding success of marine mammals, according to the report.
By damaging fish habitats and causing fish species to move to cooler waters, warming oceans are affecting fish stocks in some areas and are expected to lead to reduced catches in tropical regions, the report states.
In East Africa and the Western Indian Ocean, for example, ocean warming has reduced the abundance of some fish species by killing parts of the coral reefs they depend on, adding to losses caused by overfishing and destructive fishing techniques.
In South-East Asia, harvests from marine fisheries are expected to fall by between 10 per cent and 30 per cent by 2050 relative to 1970-2000, as the distributions of fish species shift, under a high 'business as usual' greenhouse gas emission scenario, the report states.
The report also highlights evidence that ocean warming is causing increased disease in plant and animal populations, and impacting human health as pathogens spread more easily in warmer waters, including cholera-bearing bacteria and harmful algal blooms that cause neurological diseases like ciguatera.
Warming oceans are also affecting the weather, with a range of knock-on effects on humans. The number of severe hurricanes has increased at a rate of around 25-30 per cent per degree of global warming, the report states.
Ocean warming has led to increased rainfall in mid-latitudes and monsoon areas, and less rain in various sub-tropical regions. These changes will have impacts on crop yields in important food-producing regions such as North America and India, according to the report.
The protection against climate change offered to us by oceans and their ecosystems - such as absorbing large amounts of CO2 and sheltering us from storms and erosion - is also likely to reduce as the ocean warms, according to the report.
The report's recommendations include recognising the severity of ocean warming impacts on ocean ecosystems and the benefits they provide to humans, expanding marine protected areas, introducing legal protection for the high seas, better evaluating the social and economic risks associated with warming oceans and continuing to fill gaps in scientific knowledge, as well as cutting greenhouse gas emissions rapidly and substantially.
The report was launched at the IUCN World Conservation Congress in Hawai'i.