<
https://www.theguardian.com/environment/2024/mar/09/we-cant-pretend-were-doing-enough-if-we-want-to-give-the-great-barrier-reef-a-chance-to-survive>
"What will it take for us to collectively pay attention? Not a new question,
but a reasonable one after the official declaration that the Great Barrier Reef
is suffering through another mass bleaching event driven by global heating –
the fifth since 2016.
There is no clearer visual demonstration of the climate crisis than what is
happening to the reef. It’s a globally unique landmark, made up of thousands of
individual reefs and islands and an extraordinary and eccentric array of
species. It has been growing into its modern form, spread across an area the
size of Italy, for about 8,000 years. People travel from across the planet to
witness it. And we can literally see the impact of climate change on it as it
changes colour and loses life in real time.
Widespread mass bleaching was not recorded on the reef before 1998, but has now
happened seven times. The last five were in 2016, 2017, 2020, 2022 and 2024.
Coral bleaching is a brutal process caused by inflated ocean temperatures. The
coral becomes stressed and ejects the tiny marine algae, known as
zooxanthellae, that live in its tissue and give most of its colour and energy.
With the zooxanthellae gone, the coral starves and its bone-white calcium
skeleton becomes visible.
If the elevated temperature doesn’t last long, the coral can recover.
Otherwise, it starts to die. In the most severe cases, the bleaching is
basically just skipped and the coral dies almost immediately. When it does, the
white, bleached appearance fades to dirty, scuzzy brown as it is swamped by
algae.
That’s what can happen in a one-off event. But we’re not in one-off event
territory any more and the impact of bleaching is also cumulative. The entire
length of the reef has been severely affected at some point since 2016.
Bleached coral that survives becomes more susceptible to disease and less
resilient the next time bleaching hits.
Increasingly, that’s looking like it could be every year. The most recent
bleaching event before the current one occurred during a La Niña, when ocean
temperatures are suppressed. It suggested bleaching is about to become the
status quo – if it isn’t already.
None of this is a surprise. A summary of the peer-reviewed science by the
Intergovernmental Panel on Climate Change in 2018 reporting that a majority of
tropical coral reefs would disappear even if global heating was limited to 1.5C
above pre-industrial levels. They found they would be “at very high risk” at a
rise of just 1.2C.
Average global temperatures are already nearly at this level. And ocean
temperatures, in particular, are soaring. They have been at the highest level
on record for about a year."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
