The world’s coral reefs are definitely in trouble. But as we and our colleagues argue in a study published in the journal Nature, we must not lose hope for coral reefs, despite hunting and omnipresent shade.
Instead, we have to accept that coral reefs around the world quickly become a new ecosystem emerged, contrary to what humans have known before. Realistically, we can not wait to have, maintain, conserve or restore coral reefs as was the case.
It is a message that was faced. But it also emphasizes what we need to do to ensure a realistic future for reefs and to maintain food security and other benefits they bring to society.
The last three years have been the hottest recorded, and many coral reefs in the tropics have suffered one or more flushing bleaches during long heat waves underwater.
A bleached coral may not die. But by 2016, two-thirds of the coral reefs north of the Great Barrier Reef have died in just six months due to unprecedented heat stress. This year, bleaching occurred again, this time mainly in the central part of the reef.
In both years, the southern third reef escaped with little or no bleach, as it was cooler. Therefore, it is part of bleaching and varies depending on severity, depending in part on where the water is warmer each summer and regional differences in the rate of warming. Therefore, some areas, reefs, and even local sites on the reefs, can escape from damage even during a total heat loss.
Moderate whitening events are also very selective, affecting more or less coral species and individual colonies, creating winners and losers. Coral species also differ in their ability to reproduce, which are dispersed in the form of larvae and rebound thereafter.
This natural variability offers hope for the future and represents different sources of resistance. Surviving corals continue to produce one billion larvae each year, and their genetic makeup will change under intense natural selection.
In response to fisheries, coastal development, pollution and the four whitening events in 1998, 2002, 2016 and 2017, the Great Barrier Reef is already a very disturbed ecosystem, and will change even more in the coming decades. Although the reefs are different in the future, they could still be fully functional in the coming centuries – able to withstand ecological processes and regenerate. But this will only be possible if we act quickly to curb climate change.
The Paris Climate Agreement is the fundamental framework to avoid very dangerous levels of global warming. Price levels of 1.5 degrees Celsius and 2 degrees Celsius refer to increases in global mean temperature and sea, from pre-industrial times. For most of the shallow tropical oceans, where temperatures rise more slowly than the global average, this translates to 0.5 degrees Celsius later warming towards the end of this century – slightly less than the warming of coral reefs have Known since industrialization.
If we can improve the management of the reefs to help manage this climate glove, the reefs must survive. The future of reefs will have a different combination of species, but it must still maintain its aesthetic values and support tourism and fishing. However, this cautious optimism depends entirely on the reduction of global greenhouse gas emissions from its current trajectory, which could see the annual bleaching of coral occur in most tropical places by 2050. There is no time Which you lose before you close this narrowing window.