Fig 1.
Probability of DHW events > 4°C-weeks, seasonal SST variability and inter-annual SST variability in 12 coral reef regions during the period 1986–2019.
Outliers (>100 * interquartile range) are shown by the black dots. Thresholds for determining thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1) and exposed reefs (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1) are represented by the blue and red shaded areas, respectively. Thresholds for determining high SST variability (> 0.7°C) and low SST variability (< 0.3°C) are represented by the dark and light grey shaded areas, respectively.
Fig 2.
Global distribution of exposure category in the 1986–2019 climate and at 1.5 and 2.0°C of future global warming.
Exposure categories are thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1), intermediate (probability of DHW events > 4°C-weeks from 0.1–0.2 yr‒1) and exposed (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1). Percentages indicate the regional (on map) and global (right of map) proportion of thermal refugia (blue) and exposed reefs (red). The 12 coral reef regions are outlined in light blue. The base map is made with Natural Earth.
Fig 3.
Probability of DHW events > 4°C-weeks across 12 coral reef regions under 1.5, 2.0, 3.0 and 4.0°C of global warming relative to pre-industrial levels.
Thresholds for determining thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1) and exposed reefs (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1) are represented by the blue and red shaded areas, respectively.
Fig 4.
Global distribution of exposure category and SST variability level in the 1986–2019 climate and at 1.5 and 2.0°C of future global warming relative to pre-industrial levels.
Exposure categories are thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1), intermediate (probability of DHW events > 4°C-weeks from 0.1–0.2 yr‒1) and exposed (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1). Exposure categories are split by the level of SST variability (high = seasonal OR inter-annual variability > 0.7°C, low = seasonal AND inter-annual variability < 0.3°C, moderate = all others). The 12 coral reef regions are outlined in light blue. Bars indicate the percentage of 1 km reef pixels in each exposure category. The base map is made with Natural Earth.
Fig 5.
Probability of DHW events > 4°C-weeks (a), seasonal SST variability (b) and exposure category (c) in the Northern Caribbean and Sulawesi, Indonesia at 1.5°C of global warming.
Exposure categories are thermal refugia (probability of DHW events > 4°C-weeks less than 0.1 yr‒1), intermediate (probability of DHW events > 4°C-weeks from 0.1–0.2 yr‒1) and exposed (probability of DHW events > 4°C-weeks greater than 0.2 yr‒1). Exposure categories are split by the level of SST variability (high = seasonal OR inter-annual variability > 0.7°C, low = seasonal AND inter-annual variability < 0.3°C, moderate = all others). The base map is made with Natural Earth.
Fig 6.
Percentage of thermal refugia and exposed reef pixels in 12 coral reef regions and globally in the 1986–2019 climate and at 1.5, 2.0 and 3.0°C of global warming.
As with 3.0°C, there are 0% thermal refugia and 100% exposed reefs at 4.0°C of global warming. Error bars are the percentage of thermal refugia and exposed reefs identified using the maximum and minimum probability of DHW events > 4°C-weeks simulated by the 57 sets of CMIP6 climate projections (15 models and four SSP emissions scenarios: two climate models, GFDL-CM4 and NESM3, had only two and three SSP runs available, respectively).