In the best climate future, more than 60% of corals will be threatened by 2100

Even in the best possible climate crisis scenario — which already seems far from reality — more than half of the world’s corals (64%) could be in at least an inadequate environmental condition by the end of this century. If previously long-term strategic actions were already seen as necessary to ensure the health of these beings, a new study shows that the time available to put them into practice may be shorter than imagined.

The research in question was published this Tuesday (11), in the scientific journal Plos Biology. Corals are an important and sensitive source of biodiversity on Earth, with several species dependent on these living structures, which act as shelter, breeding and feeding places.

Considering a “mid-way” climate scenario, that is, with implementation of measures to reduce greenhouse gas emissions, about 97% of the world’s corals would be under inadequate environmental conditions by 2100.

In the worst possible case, virtually all the world’s corals would be under at least pressure that would lead to an inadequate environmental situation by 2055.

According to scientists, these data suggest that the time available for corals to withstand human disturbances is half of what was thought.

“Clearly, the time for ecosystems to adapt to human disturbances is running out, while there are a reduced number of viable areas for expansion beyond the current distribution,” the researchers say.

The study sought to estimate the year after which changes in nature could definitively exceed the corals’ tolerance limits. Such limits can be defined as the thresholds recorded in scientific literature under which there were losses in coral populations, with changes in the community and in the functioning of the ecosystem.

To arrive at the key years, the researchers used projections of marine heat waves, ocean acidification, storm surges, land-based pollution, and local human changes.

That is, the scientists estimated from which date any of these variables — or several of them simultaneously — exceeded the coral threshold. It is worth mentioning that exceeding this limit will not necessarily always mean the death of these living beings, but may represent extinction events, disappearance in certain regions or adaptation.

As already pointed out, to arrive at the results, different scenarios of greenhouse gas emissions were considered according to the IPCC (UN Intergovernmental Panel on Climate Change) climate modeling. In the most optimistic, the world manages to control the temperature with an increase of about 1.8°C – we have already surpassed the 1.1°C house in relation to the pre-industrial period. In the most pessimistic, the planet can reach up to 5.7°C, in the period 2081–2100.

If the future situation seems complex, the past already pointed to problems. Scientists show that, in 2005, about 44% of the world’s corals were already facing inadequate environmental situations. The sheer number is frightening, but it is close to other estimates that the world has lost around half of its corals since 1950.

According to the study, recently, the main factor related to the unsustainability of corals are local pressures related to population density. Among the damaging points associated with such pressures are overfishing, eutrophication (in short, water pollution) and coastal development.

“The immense area of ​​corals at risk, the increasingly shorter periods of environmental sustainability, under multiple and simultaneous human interferences, combined with the limited number of areas that could serve as refuges, present a considerable challenge for the adaptation of reef ecosystems, at the same while demonstrating the urgency of implementing mitigation and conservation efforts”, say the researchers.