Ocean Warming Threatens Richest Marine Biodiversity

Creatures that make their homes in tropical waters have enjoyed mostly unchanged temperatures for the past twenty thousand years. Now, new research from the University of Adelaide suggests that these extremely biodiverse areas will be hit the hardest by climate change-induced oceanic warming – and the wildlife is not ready to adapt.

Oceanic warming is one of the most potentially devastating effects of climate change. As excess heat accumulates in our atmosphere the vast majority – approximately 90% – will be absorbed by our oceans. Increases in overall ocean temperature could cause flooding in coastal areas, drastic changes in ocean currents, and could ravage our marine life – causing serious problems for peoples’ livelihoods and our food supply.

Dr Stuart Brown from the University of Adelaide’s Environment Institute has developed a new analytical method that allows us to understand how past and future oceanic warming will affect the biodiversity of our oceans, and pinpoint which areas are at the greatest risk.

“We analysed data on the geographical distribution of over 14000 species, including algae, plants, fish, mammals, and reptiles. We also calculated two important dimensions of oceanic warming that affect marine biodiversity. Our measures of oceanic warming allowed us to quantify how vulnerable different areas and their biota would be to climate change,” Dr Brown explains.

“Our research showed that locations with exceptionally high marine biodiversity, mainly tropical and mid-latitude waters, will be the most exposed to future oceanic warming, making them particularly vulnerable to 21st century climatic change.”

Unfortunately, these extremely biodiverse environments have also previously enjoyed the most stable oceanic temperatures throughout history. That might sound like a good thing, but what it really means is that the inhabitants are ill-equipped to deal with drastic temperature change.

These vulnerable environments contain most of the world's reef-building coral species, which support the livelihoods of millions of people. Other vulnerable regions are home to iconic marine megafauna like manatees.

Importantly, now that we have pinpointed the most at-risk environments, we can develop targeted conservation strategies that will help mitigate the damage.

What’s next?

“By showing that areas of high marine biodiversity are disproportionately exposed to future warming, our results provide important new information for deriving and strengthening conservation actions to safeguard marine biodiversity under climate change,” said the University of Adelaide’s Associate Professor Damien Fordham, also from the Environment Institute.

“Actions that strengthen ecological and evolutionary resilience to climate change should be a priority. These could include improving fisheries management, assisting the movement of species, and the expansion of well-managed, climate-smart marine protected areas.”