Overview

• Sediment cores dating back to the mid-1800s indicate that algae levels across 80 Canadian lakes have surged seven-fold since the 1960s.
• Researchers attribute most of the increase to anthropogenic warming, with Canada’s temperature rise of 2.4 °C since the mid-20th century doubling the global average.
• Even lakes in remote, unspoiled catchments show significant algal growth tied to rising temperatures rather than local development.
• Runoff rich in nitrogen and phosphorus from agriculture and urban areas compounds warming effects by fueling algal blooms.
• Scientists call for cutting fertilizer use and securing global emissions reductions to protect freshwater ecosystems and public health.