Coral reefs are threatened with “bleaching” and death due to rising temperatures – scientists

Coral reefs are threatened with “bleaching” and death due to rising temperatures – scientists


The world’s main heat stress warning system for the planet’s coral reefs has been forced to add three new warning categories to reflect the ever-increasing extreme temperatures.

The changes, introduced by the government’s Coral Reef Watch program, come after reefs across America suffered unprecedented levels of heat stress last year, leading to massive coral bleaching and death, The Guardian reports.

“We are entering a new world in terms of heat stress where the effects are becoming so widespread that we have had to rethink our work.” said Coral Reef Watch Program Director Dr. Derek Manzello.

Excessive heat can cause corals to separate from tiny algae, which affects their color and nutrient content. “Bleaching” can kill corals, and those that survive will become more vulnerable to disease and have difficulty reproducing.

Discolored coral. Photo: wildam/Depositphotos

The Coral Reef Watch program, organized by the National Oceanic and Atmospheric Administration (NOAA), previously issued warnings for coral reefs in four stages, with the highest, alert level 2, indicating “probable severe bleaching and significant mortality” of corals.

Now three more alert levels have been added to the program so that scientists and conservationists can better understand the state of coral reefs in different regions. It is based on a measure of the amount of accumulated heat stress that corals are experiencing at any given time, known as a degree-heat week.

For example, one degree heat week is accumulated if corals are exposed to temperatures one degree Celsius above the maximum for seven days.

The old system had a peak of eight degree heat weeks or higher. On the other hand, last year in the summer in the Northern Hemisphere, the reefs experienced heat stress that significantly exceeded this mark – 20 degree heat weeks.

“We know that coral mortality begins with eight degrees of warming. But now the situation is becoming catastrophic – more than 20 degrees in a week. This is similar to a category five cyclone with incredibly severe damage. This is the worst-case scenario.” – said Dr. Derek Manzello.

From now on, the new warning system looks like this:

  • the third level – from 12 to 16 degree heat weeks (HTT);
  • the fourth level – from 16 to 20 GTT;
  • the fifth level is above 20 HTV, there is a risk of “almost complete mortality” of all corals.

Professor Tracey Ainsworth, vice-president of the International Coral Reef Society, said heat stress was a rare occurrence as recently as a decade ago.

“But now we are talking not just about discoloration, but about mortality – and this is exactly the consequence of these changes”the professor explained.

We will remind, forecasters recorded a record high temperature in continental Europe.

Vira Shurmakevich, “UP. Life”

Read also: The temperature of the surface of the world ocean has reached a record value – scientists



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