A long-term (50 years) study of a Great Barrier Reef (GBR) ecoystem finds corals may quickly recover from El Niño disturbances.
According to scientists (Yan et al., 2019), coral reef ecosystems thrive in centennial-scale warming phases such as the Medieval Warm Period and Current Warm Period, whereas they experience population declines (“switch-off” episodes) during cold periods (the Little Ice Age).
Image Source: Yan et al., 2019
Indeed, corals prefer the warmest waters, which is why they predominantly live near the equator.
Image Source: NOAA
Popularized claims of a greater than 90% coral reef mortality after the 2015-’16 El Niño event are common in media circles (“93 Percent Of The Great Barrier Reef Is Practically Dead“).
Yet GBR expert Dr. Peter Ridd reports (at the 6:00 mark) that even the “extreme” estimate of reef deaths may not have exceeded 8%, and that corals “can actually recover from that within a year.”
Further, Ridd states that between 2011 and 2016, there was a 250% increase in coral cover in the southern GBR, and the abundance of corals in 2019 is no less than 1985.
In a new paper (Davis et al., 2019), scientists compare the growth (calcification) rates for corals observed in the 1970s at One Tree Island (Great Barrier Reef) to today.
Though it’s thought it may take about 9-12 years for corals to recover from El Niño disturbances (Guoezo et al., 2019), Davis and colleagues document a 400% increase in coral growth rates between 2014 and 2017, or before and after the “devastating” 2015-’16 El Niño event.
Furthermore, when comparing the 1970s to 2017, they find calcification rates were “comparable” for corals over the 50-year period.
Long-term observations would appear to offer necessary context to claims that climate change is igniting irreparable and unprecedented harm to coral ecosystems.