Coral Bleaching HotSpot Aug 16, 2020

Goreau-Hayes Coral Reef Bleaching HotSpot Map for August 16, 2020. NOAA Coral Reef Watch Daily 5km coral bleaching record. Ocean sites with SST anomalies range from 1°C (yellow), 3°C (red), and > 5°C (black). Purple anomalies are <1°C.


30 years ago we developed the HotSpot method of predicting coral bleaching caused by extreme heat waves, using satellite Sea Surface Temperature (SST) anomalies mapped with regard to the average temperature in the hottest month historically (Goreau & Hayes, 1994).

GCRA’s HotSpot method correctly predicts mass coral bleaching events. Early this year we predicted bleaching in the Great Barrier Reef, then Indonesia, India, the Philippines, China, Taiwan, and more. The 2020 Northern Hemisphere bleaching season is only starting.

Great Barrier Reef now at severe bleaching temperatures

Great Barrier Reef bleaching should decrease

When we developed the Coral Bleaching HotSpot method 30 years ago we pointed out that coral reefs had already passed the temperature tipping point for mass coral bleaching in the 1980s, and that while coral reefs would be the first ecosystem to go functionally extinct from global warming, others would follow. Governments ignored our warnings and let reefs die from heat stroke. Polar Ice is next!

Earth passed coral bleaching tipping point in 1980s

Although we developed the HotSpot method for coral bleaching heat stroke in tropical waters, it is the ideal measure of Arctic heat waves triggering massive polar ice cap melt. It takes a 1°C (yellow) anomaly for a month to cause coral reef bleaching, but black areas mark Arctic Ocean anomalies more than 5°C above the average historical temperature in the warmest month!

These extreme marine heat waves herald imminent loss of summer Arctic Ice and even more rapidly rising global temperatures in the near future. As white Polar ice melts and is replaced by dark blue water, the albedo positive feedback will really accelerate runaway global warming: loss of Arctic summer ice will increase sunlight absorbed at the surface from 40% to 90% (Peter Wadhams, 2017, A Farewell To Ice: A Report From The Arctic, Oxford). If not reversed, there will eventually be up to 70 meters of sea level rise when Antarctica melts.

There is little time left for either coral reefs or Arctic ice if we don’t reverse CO2 increase immediately!

Canada’s last intact ice shelf collapses due to warming:

Canada’s last intact ice shelf collapses

One of the world’s top glaciologists just drowned in the bottom of a Greenland crevasse at his research station that wasn’t there before:

Konrad Steffen dead

Carbon Dioxide Removal is far more urgent than any politician realizes!