Solar Geoengineering Could Protect Most Oceans from Heat Waves

Solar geoengineering could shield up to 75% of the world's oceans from marine heat waves. This is according to a study by researchers at Michigan State University. The controversial strategy involves injecting aerosols into the stratosphere to reflect sunlight.

Marine heat waves are becoming longer and more frequent. They threaten global seafood supplies. The study, published in *Environmental Research: Climate*, used computer simulations. These simulations forecasted marine heat waves with and without solar geoengineering.

One scenario modeled enough sun-blocking particles to keep Earth's air temperature at 1.5 degrees Celsius above pre-industrial levels. This moderate approach protected 20% to 25% of the ocean from worsening heat waves. A more aggressive scenario aimed to reduce atmospheric warming to less than one degree Celsius. This approach increased protection to 75% of the oceans.

The tropical Atlantic, Indian Ocean, Arctic Ocean, and South Atlantic Ocean showed the most benefit. However, nearly 25% of the world's oceans would still experience longer, hotter heat waves. These areas include the North Atlantic and parts of the Pacific Ocean. Previous research shows that ocean temperatures are projected to rise by one degree Celsius by 2069 without intervention. This would cause marine heat waves to become hotter and longer across 97% of the world's oceans.

Stratospheric aerosol injection mimics the cooling effects of volcanic eruptions. Volcanoes release sulfur dioxide and other gases into the atmosphere. These form droplets that reflect sunlight, causing temporary global cooling. For example, the 1991 eruption of Mount Pinatubo lowered global temperatures by approximately 0.6 degrees Celsius for two years.

Scientists emphasize the need for more research into the potential consequences of solar geoengineering. Most studies have focused on atmospheric warming. The impacts on oceans remain less clear. This new research highlights the uneven protection solar geoengineering might offer.