The phenomenon of coral bleaching is becoming increasingly common along the Great Barrier Reef in Australia. According to the Australian Institute of Marine Science (AIMS), it happened in 2020 and has now occurred again.
When the water is too warm, corals expel zooxanthellae, an algae living in their tissues -- reducing themselves to survive the heat better. The coral is not dead, just slimmer, under greater stress, and thus more vulnerable.
The
US lost half of its coral reefs in the Caribbean in 2005, when warm
waters, centered near the Virgin Islands and Puerto Rico, expanded
southward. Satellite data confirmed the thermal stress had been greater
than the total of the previous 20 years.
Algae
is the coral's primary food source and gives it color while the coral
provides a protected environment for the algae. Thus the two enjoy a
symbiotic relationship which under temperature stress can cause the
algae to leave. Having lost its principal food source, the coral turns
very pale and becomes susceptible to disease. It can take as long as a
decade to recover from such trauma.
Thus
back-to-back bleaching events as on Australia's Great Barrier Reef are cause
for concern. This is now its fourth mass bleaching event in six years.
The heat stress can slow coral growth and limits its spawning
abilities, extending the effects to new generations. Seeding the damaged areas with healthy coral often developed in nurseries to withstand such stresses is another technique.
Meanwhile,
the Australian government continues its support of fossil fuel
industries, particularly coal and natural gas, even though coal is
recognized as the worst fossil fuel polluter responsible for 0.3Â degreesC of the
1Â degreesC increase in global mean temperatures.
These
temperatures are expected to rise 3.2Â degreesC by the end of the century at the
present rate making the lives of our successor generations exceedingly
difficult as they cope with frequent adverse weather events like
wildfires, hurricanes or typhoons.
The UN Intergovernmental Panel on Climate Change (IPCC) has now presented its guidelines on what we must do to limit temperature rise to 1.5Â degreesC.
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