Yan et al., 2019
is a 50 year study
of a Great Barrier
The study found
that GBR corals
quickly recover
from El Niño
ocean disturbances.
Scientists say coral reefs
thrive in centennial-scale
warming phases, such as the
Medieval Warm Period, and
Current Warm Period, but
experience population declines
during cold periods, such as
the Little Ice Age.
Corals prefer the warmest waters,
so mainly live near the equator.
The single biggest threat
to the Great Barrier Reef
is sea level fall.
Sea levels fell 30 centimeters
during the recent super El Nino
event of 2015 / 2016.
This is not a large amount
considering that the tidal range
could be over one meter.
But 30 centimeters was enough
to result in bleaching of the top
30 centimeters of a coral
that may be subject to sunshine
on the exposed reef flat for
perhaps an hour.
There had been
false claims
of up to a 93%
coral reef mortality
after the late 2015
- early 2016 Pacific
Ocean "El Niño" event.
But GBR expert Dr. Peter Ridd
reports that even the “extreme”
estimate of reef deaths
may not have exceeded 8%,
and that corals “can actually
recover from that within a year.”
Ridd states that between
2011 and 2016, there was
a 250% increase in coral cover
in the southern GBR, and the
coral cover in 2019 is
similar to back in 1985.
Davis et al., 2019 compares
the growth (calcification) rates
for corals observed in the 1970s
at One Tree Island (GBR), to today.
Davis and colleagues document
a 400% increase in coral growth
rates between 2014 and 2017,
both before, and after,
the 2015-’16 El Nino.
When comparing
the 1970s to 2017,
they find calcification rates
were “comparable” for corals
over the 50-year period.
It may take about 9- to 12 years
for corals to recover from
El Niño disturbances
( Guoezo et al., 2019 )
Long-term observations
refute the common claim
that climate change is doing
unprecedented harm
to coral ecosystems.