Coping with commitment: projected thermal stress on coral reefs under different future scenarios

Area of Science:

• Marine Biology
• Climate Science
• Ecology

Background:

• Anomalously warm ocean temperatures cause mass coral bleaching.
• Anthropogenic climate change increases the frequency of thermal stress events, threatening coral reef ecosystems and dependent human populations.
• Greenhouse gas mitigation's near-term impact is limited by the time lag between emissions and climate response.

Purpose of the Study:

• Evaluate the "committed warming" for global coral reefs using observed sea surface temperatures and climate models.
• Assess the impact of different future emissions scenarios on coral reef thermal stress.
• Determine the potential of adaptation to mitigate the effects of warming.

Main Methods:

• Utilized observed sea surface temperatures.
• Employed global climate models forced with five distinct future emissions scenarios.
• Analyzed the projected frequency of harmful thermal stress events for coral reefs worldwide.

Main Results:

• Current greenhouse gas accumulation commits over 50% of coral reefs to frequent thermal stress by 2080.
• A "societal" warming commitment could lead to over 80% of reefs experiencing frequent stress by 2030.
• 1.5°C of thermal adaptation could delay these forecasts by 50-80 years.

Conclusions:

• Adaptation (biological, community, or management) may allow avoidance of frequent thermal stress for 97% of reefs this century.
• Without adaptation, atmospheric CO(2) must stabilize below current levels to prevent coral reef degradation.
• Urgent action on emissions and adaptation is critical for coral reef survival.