Flickr.com/Matt Kieffer CC-BY-SA
The soaring temperature of the oceans is the “greatest hidden challenge of our generation”and global coral bleaching continues for a third year due to global warming.
The US National Oceanic and Atmospheric Administrations (NOAA) and its project Coral Reef Watch reports that the world is in a third year of coral bleaching across the globe. “This is the most widespread, longest coral bleaching event ever to occur globally,” Mark Eakin, the director of NOAA Coral Reef Watch, said.
The soaring temperature of the oceans is the “greatest hidden challenge of our generation” that is altering the make-up of marine species, shrinking fishing areas and starting to spread disease to humans, according to a new International Union for Conservation of Nature (IUCN) report on ocean warming.
Warming is already causing fish, seabirds, sea turtles, jellyfish and other species to change their behaviour and habitat, it says. Species are fleeing to the cooler poles, away from the equator, at a rate that is up to five times faster than the shifts seen in species on land. Even in the north Atlantic, fish will move northwards, with shifts already documented for pilchard, anchovy, mackerel and herring. The warming is having its greatest impact upon the building blocks of life in the seas, such as phytoplankton, zooplankton and krill. The movement of fish will create winners and losers among the 4.3 billion people in the world who rely heavily upon fish for sustenance. In Southeast Asia, harvests from fisheries could drop by nearly a third by 2050 if emissions are not severely curtailed. Humans are also set to suffer from the spread of disease as the ocean continues to heat up. The IUCN report found there is growing evidence of vibrio bacterial disease, which can cause cholera, and harmful algal bloom species that can cause food poisoning. People are also being affected by more severe, if not more numerous, hurricanes due to the extra energy in the ocean and atmosphere.
Ocean acidification, where rising carbon dioxide absorption increases the acidity of the water, is making it harder for animals such as crabs, shrimps and clams to form their calcium carbonate shells.
Coral reefs, which support around a quarter of all marine species, are suffering from episodes of bleaching that have increased three-fold in the past 30 years. This bleaching occurs when prolonged high temperatures cause coral to expel its symbiotic algae, causing it to whiten and ultimately die.
NOAA says that over the past two years, reefs have been essentially boiled to death in parts of every ocean basin on earth. Abnormally hot waters have turned vibrant coral communities into pale white ghost communities as heat has sapped coral of the algae they need to survive. There are only two other global coral bleaching events to precede this one: in 1998 and 2010. Both came during El Niño years. This event is different, it started in 2014, when El Niño was just beginning, and it’s still going strong in the middle of 2016 despite El Niño’s passing.
Reefs in many countries have been hit (see map from NOAA), 40 per cent of reefs have been affected globally, and 70 per cent of US reefs, including the Florida Keys. Other locations affected include the US Virgin Islands, Puerto Rico, and reefs near Hawaii, Guam and the Commonwealth of the Northern Mariana Islands. The Great Barrier Reef has also been hit hard with up to 93 per cent of the reef showing signs of bleaching. Other parts of the ocean have been equally devastated, including some of the most pristine reefs on the planet that lie in the middle of the Pacific.
Compiled by Reinhold Pape
Sources:
Link to NOAA Coral Reef Watch report: http://coralreefwatch.noaa.gov/satellite/analyses_guidance/global_coral_bleaching_2014-17_status.php
Link to IUCN report: http://www.iucnworldconservationcongress.org/news/20160905/article/global-warning-ocean-warming
Coral bleaching forecast, 60% probability for coral bleaching thermal stress for June to September 2016. Source: NOAA Coral Reef Watch
