Gif: Thermal stress around the Great Barrier reef from January-March 2017
by NOAA Climate.gov image by Dan Pisut, based on NOAA Coral Reef Watch maps.
At the beginning of 2017, no heat stress is apparent, but this situation soon changes. Degree heating weeks begin to accumulate soon after the start of the year. By the end of January, heat stress associated with likely bleaching is apparent. The situation only worsens in February, and by the end of that month, heat stress high enough to cause significant bleaching and coral death occurs over an expansive area. By the end of March, a substantial area off the coast of northeast Australia shows heat stress values of 8 or higher.