Philippe Van Cappellen, Professor, Faculty of Science, Department of Earth and Environmental Sciences, Canada Excellence Research Chair Laureate in Ecohydrology
Within the next 15 years more than 90 per cent of the world’s rivers will become fragmented by at least one dam. It is known that human-constructed dams alter ecosystems on a local scale. However, it is less understood what impact they have on a global scale, particularly how they disrupt the movement of carbon between the land, water and atmosphere.
In a landmark study that appeared in Nature Communications, Philippe Van Cappellen and his graduate student Taylor Maavara found that reservoirs created by dams significantly impact the world’s carbon cycle, and consequently also the climate system, in ways that had not been previously accounted for. Using a novel modelling technique they discovered that nearly one-fifth of the organic carbon that moves from land to ocean is trapped by human-constructed dams. They also pinpointed Southeast Asia and South America, where many new dams are being built, as hotspots for the largest changes to be seen in the carbon export from continents to the ocean in the coming decades.
“Dams don’t just have local environmental impacts. It’s clear they play a key role in the global carbon cycle and therefore Earth’s climate,” he says. “For more accurate climate predictions, we need to better understand the impact of reservoirs.”