Scientists warn of dire effects as Mediterranean heats up

MADRID (AP) — Vacationers can enjoy the summer heat of the Mediterranean, the weather As it burns in a series of intense heat waves, scientists are warning of dire consequences for marine life.

From Barcelona to Tel Aviv, scientists say they are seeing an exceptional rise in temperatures for this time of year, ranging from 3 degrees Celsius (5.4 Fahrenheit) to 5 degrees Celsius (9 Fahrenheit). Water temperatures regularly exceed 30 °C (86 °F) on some days.

Extreme heat has grabbed headlines this summer in Europe and other countries around the Mediterranean, but rising sea temperatures are largely out of sight and out of mind.

Ocean heat waves are caused by ocean currents creating areas of warm water. Weather systems and atmospheric heat can also pile up degrees to water temperatures. And like their counterparts on land, human-induced climate change is making ocean heat waves longer, more frequent and more intense.

Joaquim Garabo, a researcher at the Institute of Marine Sciences in Barcelona, ​​says the situation is “very alarming.” “We are pushing the system too far. We have to act on climate issues as soon as possible.”

Garrabou is part of a team that published a report on Mediterranean heat waves between 2015 and 2019. The report says these incidents have caused “massive die-offs” of marine species.

According to a study published in the journal Global Change Biology, about 50 species, including corals, sponges and seaweeds, have been affected along thousands of kilometers of Mediterranean coastline.

The situation in the eastern Mediterranean basin is particularly dire.

The waters off Israel, Cyprus, Lebanon and Syria are “the warmest places in the Mediterranean, for sure,” said Gil Rilov, a marine biologist at Israel’s Oceanographic and Limnological Research Institute and a co-author of the paper. Average summer sea temperatures are now consistently above 31 C (88 F).

These warming seas are driving many native species to the brink, “because their optimum temperatures are being exceeded every summer,” he said.

What he and his colleagues are seeing in terms of biodiversity loss is projected to continue in the Mediterranean region in Greece, Italy and Spain in the next few years.

Garabu noted that oceans serve the planet by emitting 90% of Earth’s excess heat and 30% of carbon dioxide into the atmosphere through coal, oil and gas production. This carbon-sink effect protects the planet from more severe climate impacts.

This was possible because the oceans and seas were in a healthy state, Garabu said.

“But now we have driven the ocean to an unhealthy and dysfunctional state,” he said.

Halting ocean warming will require drastic reductions in Earth’s greenhouse gas emissions, while ocean scientists are looking for authorities to guarantee that 30% of the ocean’s surface is specifically protected from human activities such as fishing, giving species a chance. To recover and thrive.

About 8% of the Mediterranean Sea is currently protected.

Garabu and Rilov said policymakers do not know much about the warming of the Mediterranean Sea and its impact.

“It’s our job as scientists to bring this to their attention so they can think about it,” Rilove said.

Heat waves occur when particularly hot weather continues for a number of days, with no rain or little wind. Land heat waves help generate ocean heat waves, and the two feed off each other in a vicious, warming circle.

Land heat waves have become common in many countries around the Mediterranean Sea, with dramatic side effects such as wildfires, droughts, crop losses and alarmingly high temperatures.

But ocean heat waves could also have serious consequences for countries bordering the Mediterranean and the more than 500 million people who live there, if not addressed quickly, scientists say. Fish stocks will be depleted and tourism will be adversely affected, as destructive storms may become more common over land.

Despite representing less than 1% of the global ocean surface, the Mediterranean is one of the main reservoirs of biodiversity, containing between 4% and 18% of the world’s known marine species.

Some of the most affected species are important for maintaining the functioning and diversity of marine habitats. Species such as Posidonia oceanica seagrass meadows, which absorb large amounts of carbon dioxide and support marine life, or coral reefs, which are also home to wildlife, will be at risk.

Garabu says the mortality effects on the species were observed between the surface and 45 meters (about 150 feet) deep, where recorded ocean heat waves were exceptional. Heat waves affected more than 90% of the surface of the Mediterranean Sea.

According to the most recent scientific papers, sea surface temperatures in the Mediterranean have increased by 0.4 C (0.72 F) per decade between 1982 and 2018. On an annual basis, it has increased by about 0.05 C (0.09 F). Over the last decade with no sign of letting up.

Experts say even a few degrees could have a detrimental effect on ocean health.

Affected areas have also increased since the 1980s and now cover most of the Mediterranean, the study suggests.

“The question is not the survival of nature, because biodiversity will find a way to survive on the planet,” Garabu said. “The question is, if we keep going in this direction, our society, our people, may not have a place to live.”


Ilan Ben Zion reports from Jerusalem.


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