Marine Research & Ocean Climate Change [2024.H1]

GBR Mass coral bleaching event update (9 April 2024): Preliminary analysis by CoralWatch team’s @JezRoff
– Satellite data for degree heating weeks (DHW) clearly outline the record intensity and impact.
– 46% of reefs experienced record high DHW.
– New record of 17.7 DHW from southern GBR.
– 37% of GBR has been exposed to three or more >6DHW events in the past decade.
– Mass bleaching events are increasing in frequency and intensity since 1986.
– 31% of the southern “refugia” reefs have been exposed to >4DHW for the first time in over three decades.
– High (4-8 DHW) and severe (8-12 DHW) exposure categories are becoming commonplace.
– The intensification from the first event (1998) through to 2024 is striking.
– Sustained high DHW across much of the reef => predicted high mortality.
– Despite temperatures dropping, many reefs (eg: Heron Island) continue to experience sustained record DHW exposure.
– Awaiting results of in-water surveys
– AIMS PDF (15 Apr): Aerial surveys of the 2024 mass coral bleaching event on the Great Barrier Reef

PDF (15 April 2024) – AIMS Aerial surveys of the 2024 mass coral bleaching event on the Great Barrier Reef

• AIMS Reef Health Updates > 26 April 2024
• Ocean temperatures started building in late December through to late February throughout all three regions of the Great Barrier Reef, causing the highest levels of thermal stress on record.
• In March 2024, the fifth mass bleaching event on the Great Barrier Reef was confirmed.
• This year for the first time, extreme bleaching (90% bleached coral cover) was observed in all three regions of the GBR.
• 73% of GBR reefs have prevalent bleaching (>10% bleached coral cover).
• 60% of GBR reefs were exposed to dangerous levels of heat stress (bleaching and mortality risk).
• 46% of GBR reefs experienced record levels of heat stress.
• 39% of GBR reefs experienced ‘very high’ to ‘extreme’ (61-90%+ coral cover) levels of bleaching
• GBR’s southern inshore reefs experienced the most intense and prolonged heat stress ever recorded: SST at +2.5°C above average, and 15 degree heating weeks.
• By 26 April, the SSTs across the whole Marine Park had cooled to below the average summer maximum (and below the coral stress threshold) but remain above the long-term April average (by +1°C to +1.5°C).

Maldives (& Region)

Maldives (& Region): NOAA data tools (as at 25 May 2024)

The current data suggests that ocean temperatures have fallen in the Maldives (and the wider Indian Ocean region).

• SSTs for the Maldives have fallen below the bleaching threshold, and currently hover around the max monthly mean for May (~30°C).
• This year’s heat stress does not appear to be as severe as experienced in 2016 (early forecasts were inconclusive).
• We have observed widespread coral bleaching across the Maldives, but hopefully the levels of coral mortality will be lower than 2016.
• The accumulating global ocean heat content has not affected the Indian Ocean region as badly as other parts of the world.
• It’s possible that the effects of the Indian Ocean Diople (IOD) has dampened the warming El Nino patterns in the region, by bringing increased cloud cover and unusually heavy rainfall (as experienced in the Maldives during May).

Climate Animations (click to play)

NOAA CoralWatch: Maldives as at 01 June

2024 Ocean Temperatures Fall to 2023 Levels for First Time
A glimmer of good news this month, as global ocean temperatures finally stop breaking all-time records, and fall ever-so slightly below those recorded during 2023. (This could be due to ENSO moving away from El Niño and towards the La Niña phase.)
Despite this good news, it’s important to note that global land/ocean temperatures continue to be elevated, relative to previous decades.

Temperature & Rainfall Forecasts (June-September 2024) – SASCOF-28 and CSUF, Pune, India (April 2024).
Statement [PDF] on the Seasonal Climate Outlook over South Asia for the 2024 Southwest Monsoon Season (June – September)
Forecast for the 2024 SW monsoon season over most parts of the South Asia region:
– Above normal rainfall, along with above normal min-max temperatures