Warming coral reefs in the past, present and future: an interview with PLOS Climate authors

Recent publications in PLOS Climate have highlighted how marine heatwaves are becoming the ‘new normal’, and the vulnerability of coral reef ecosystems to warming oceans. We spoke to the authors of a new study, which suggests that Caribbean reefs have been warming for more than a century and are on course for a further 1.5 °C of warming by 2100.

In conversation with Colleen Bove and colleagues, authors of “One Hundred and Fifty Years of Warming on Caribbean Coral Reefs”

What made you decide to investigate this issue?

Ocean warming is one of the most severe threats to marine ecosystems globally, and especially Caribbean coral reefs. We wanted to assess long-term temperature patterns (i.e. rates of warming and marine heatwaves) across the Caribbean and report these patterns in an easily interpretable way to make these data more broadly usable. Additionally, we wanted to have a temperature analysis specific to the Caribbean that was updated through 2020 to account for local recent changes in temperature patterns that may not be detected in larger scale syntheses. 

How did you go about your analysis?

To complete our study, we first identified several freely accessible sea surface temperature databases (from the MetOffice, NOAA, and NASA) that covered a variety of spatial resolutions, temporal scales, and included satellite and in situ data. We also compiled a database of known reef locations across the Caribbean from previously published research and other sources (e.g. Atlantic and Gulf Rapid Reef Assessment and Reef Check) to be able to assess temperature trends specific to coral reef locations. We were then able to assess temporal temperature trends across the entire Caribbean and on specific reef locations from as early as 1871. Finally, we also quantified marine heatwave events (unusually warm sea surface temperatures lasting for at least 5 days) since 1981 on coral reefs and the wider Caribbean.  

What were your key findings?

Overall, we found that Caribbean reefs have been warming for at least a century, although some regions within the Caribbean began warming in the late 19th century (e.g. southern and western ecoregions). Warming rates flattened in the mid-1900s, similar to other global warming patterns. Warming resumed in the late 20th century at rates of about 0.18 °C per decade. If this average rate of warming continues, Caribbean reefs may warm by an additional 1.5 °C by 2100, posing serious risk for reef inhabitants. On top of these chronic warming trends, we found that marine heatwaves are increasing in frequency and duration. Caribbean reefs are currently experiencing about five times as many marine heatwave events per year compared to the 1980s and these events are lasting on average two weeks.

What actions do you hope to see in response to your findings?

We hope that this work draws attention to the warming that Caribbean coral reefs have experienced since the early 20th century that will only continue to worsen unless climate action is taken globally. Significant global efforts need to be taken to reduce greenhouse gas emissions if we hope to maintain what remains of the world’s coral reefs and many other fragile, yet important, ecosystems.

Why did you choose PLOS Climate as a venue for your work?

We wanted to ensure that our work was open access to allow wide dissemination of our findings to anyone interested, especially researchers, policy makers, and individuals across the Caribbean. PLOS Climate presented a perfect solution for presenting our work to a wide audience in a topical journal covering all types of climate research.