Underwater heat waves are caused by global warming. The current heat wave has lasted since 2014, and it is expected that by the end of 2015 38% of coral reefs will be affected and 5% will have been completely killed off. The prediction at present is that this heat wave will last until at least mid-2016.
The heat wave consists of a huge volume of warm water, also referred to as The Blob, which has already caused an incredible amount of damage. At present some 12,000 square kilometres of coral reefs are under threat. Like in 1998 and 2010, experts are issuing an alert, because this time, just as in the previous occasions, the heat wave coincides with El Niño, which occurs every four to ten years.
The coral reefs are very important to underwater ecosystems, being crucial to approximately one-quarter to one-third of all sea life. This means that when coral reefs die the entire ecosystem is slowly disrupted, with almost unimaginable consequences.
Aside from the direct effect on the corals, warmer water also influences other factors. For example, many fish species require more energy to propel themselves in warming seawater, while there will also be less food available for them.