KAUST study reveals climate change impact on the Red Sea

The waters of the Red Sea have warmed sharply by 0.7°C since 1994, according to a recent study of satellite-derived sea surface temperatures (SST) and ground-based air temperatures by a team of researchers at King Abdullah University of Science and Technology (KAUST)¹.

The SST data were collected from monthly measurements taken by the AVHRR Pathfinder V5 dataset, one of the most accurate and reliable datasets available for the region, between 1985 and 2007. In contrast, global ocean temperatures have increased by an average 0.5°C since the mid-1970s, suggesting that the Red Sea is warming faster than the world average.

The researchers say that climate change could be behind the rise. "We cannot say with confidence which factor led to this abrupt warming," says Ibrahim Hoteit, a lead investigator on the study. "However, our analysis suggests that the pattern isn't caused by a regional phenomenon, but follows trends in the whole of the northern hemisphere."

The study contrasted the observed warming in the Red Sea with northern hemisphere temperatures acquired from the Climate Research Unit at the University of East Anglia and the UK Met Office Hadley Centre in Exeter, United Kingdom, to help determine whether the trend was only regional. The researchers found both data sets parallel one another significantly.

Air temperatures measured on the ground correlated with the SSTs, but with an average lag in sea warming of one month. "Both of these findings suggest that climate change is probably behind the Red Sea warming," says Hoteit.

The researchers note that the abrupt nature of the temperature rise in the Red Sea may make it difficult to predict future temperature changes there based on previously available models.

It is unclear how this warming pattern could affect the local ecosystem. Marine biologists, environmentalists and scuba divers have often lauded the resilience of Red Sea coral reefs and their relative insensitivity to changes in water temperature.

Mahmoud Hassan Hanafi, a marine biologist at Suez Canal University, Ismailia, Egypt, insists that as coral reefs continue to bleach and die around the world, the last survivors will likely be the corals of the Red Sea.

"Nobody knows why this is," says Hanafi, "but it is likely to do with the fact that these corals evolved in an already warm body of water." Hanafi says that the Red Sea is in a region with varied seasonal conditions, suggesting its corals have evolved to endure significant changes in temperature throughout the year.

A study published in Science in 2010, however, found that rising SSTs in the Red Sea have slowed the growth of healthy colonies of Diploastrea heliopora, a massive coral species, by 30% since 1998. The study authors warned that this particular species could stop growing by 2070².

One of the factors impeding researchers to interpret the ramifications of these findings is the relative paucity of information available on the ecological systems in the Red Sea.

"Nobody has a clear idea about what types of reef-building zooxanthellae exist in the Red Sea," says Hanafi. "Obtaining more data about their nature and qualities will be key to really understanding the implications of climate change on the Red Sea's ecosystem."

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