Increased activity of the El Niño was the cause of the extinction of coral reefs in the Pacific Ocean about 4 — 1.5 thousand years ago — this scenario could be repeated in the near future due to climate change, reinforce this climatic phenomenon, say marine scientists in a paper published in the journal Science.
El Niño ("the boy" in Spanish) is characterized by an abnormal increase in the sea surface temperature in the central and eastern tropical Pacific Ocean. This process is the inverse of the La Niña ("girl"), which is associated, however, with a cold snap in the same area of the ocean. These states follow each other at regular intervals for a year.
And El Niño and La Niña affect circuit circulation of ocean and atmospheric currents, which in turn affects the weather and climate around the globe, causing drought in some regions, and heavy rains — in others.
Climate record of the ocean
A group of biologists and climatologists led by Richard Aronson (Richard Aronson) from Institute of Technology in Melbourne, Florida (USA) restored the history of coral reefs in the Pacific Ocean in the last six thousand years, studying the remains of coral in the waters off the islands of Contador and Iguana, to west of the Panama Canal.
As the scientists explain, coral colony is one of the most sensitive indicators of climate change in the ocean. The slightest change in the average temperature of the water, the movement of currents and acidity affect the ability of corals to build calcareous shells. In particular, warming waters and acidification prevent polyps capture calcium ions and carbon dioxide, which has a negative impact on the health of coral reefs.
Aronson and his colleagues have learned deposits of fossilized shells of corals in the last six thousand years, and calculated the rate of growth. It turned out that about four thousand years ago, the formation of new polyps virtually ceased. Scientists do not believe so unexpected results and check them out by studying sediments of coral reefs off the coast of Japan and Australia. The new data confirm the initial findings oceanographers.
"Boy," and the corals
"We were shocked by the fact that the deposits simply no traces of growth for 2,5 thousand years of history. This time gap is about 40% of the total duration of the studied period. Coral reefs are considered fairly resilient ecosystems, and as a strong, broad-based and long-lasting collapse likely to have been caused by climate change. This change was the strengthening El Niño "- explained one member of the group One Lauren (Lauren Toth) of the Florida Institute of Technology.
As the scientists explain, the collapse of coral reefs in the Pacific, coincides with increased El Niño at this time due to periodic climatic fluctuations. Increasing strength of El Niño led to a rising water temperature and other changes that adversely affected the lives of the colonies of polyps.
According to oceanographers, further changes in the work flow and increase average temperatures in the Pacific Ocean due to climate change may lead to similar consequences.
"Climate change could once again destroy the coral reef ecosystem, but in this case, the main reason is the" attack "of humanity on the environment and the effect of the death of corals will be longer. Local problems such as pollution and overfishing must be stopped but their strength pales to climate change, which is a major threat to reefs today, "- concludes One.