Human freshwater footprint larger than expected shows new study in Science
The study carried out by the researcher Fernando Jaramillo, which is now being published in Science, was part of his thesis at Stockholm University, although the thesis was completed in part during the time he held a post-doctoral position at the University of Gothenburg, where he now also works part-time.
“It is an established fact that dams and irrigation systems serve to regulate water, and the local impact they have on rivers and water ecosystems is well known. However, this study shows us that dams and irrigation systems are also major consumers of water when seen from a global perspective,” says Fernando Jaramillo, who is employed by both Stockholm University and the University of Gothenburg.
The new study shows that dams and irrigation systems consume significantly more fresh water than has previously been thought and, moreover, they have a global impact. An increase in both evaporation and the transpiration of water in plants is accelerating the rate of water loss in the atmosphere and means that there is less water available on land.
“The small things we do on the surface of the Earth can have a huge global impact. In the past of the impact of human activity has been underestimated. This impact has indeed been greater than that we have seen in the form of climate change,” says Fernando Jaramillo.
A hundred years of studying the use of water
The results have raised the previous estimate of the global human footprint in terms of fresh water consumption by nearly 20 percent. The total increase in the loss caused by humankind of fresh water in the atmosphere is calculated at 4,370 sq m3 per year.
“That is the equivalent of two thirds of the annual river flow of the entire Amazon River, which is in a league of its own as the world’s largest catchment basin,” says co-author Gia Destouni, who is based at Stockholm University.
Nevertheless, it has still not been established how much water this involves at global level.
“We need first to quantify and identify the most important incentives for water consumption and to understand the impact this has, in order that we can address the future challenges relating to climate change that result from greenhouse gas emissions and water availability”.
Article in Science: Jaramillo, F., Destouni, G., 2015. Local flow regulation and irrigation raise global human water consumption and footprint. Science 350, 1248–1251. doi:10.1126/science.aad1010
Text by Carina Eliasson, University of Gothenburg