Harmful algal blooms degrade inland aquatic ecosystems and pose a risk to water security. This Review explores the underlying drivers of hotspots and global trends in harmful algal blooms, and identifies potential solutions for bloom monitoring and mitigation.

Mine tailings are voluminous and often toxic wastes, whose management is a global safety and sustainability challenge. This Review summarizes the major tailings storage facility disasters and impacts, emphasizing the urgent need for risk reduction approaches for management and policy.

The Indian Ocean Dipole (IOD) exerts strong control on the Indo-Pacific climate. This Review outlines twenty-first-century changes in the IOD, noting robust increases in eastern pole sea surface temperature variability, more frequent strong and early positive IOD events, and less frequent moderate positive IOD events.

Engineered nanomaterials (ENMs) have numerous environmental applications, such as in water treatment and reuse. This Review explores the trade-offs between the risks and benefits of environmental ENMs, and highlights that the environmental and health risks of ENMs are relatively low when used responsibly.