Global extent of rivers and streams

The surfaces of rivers and streams are interfaces for a host of chemical exchanges with the atmosphere and biosphere. For instance, carbon dioxide outgassing from rivers is estimated to be equivalent to one-fifth of combined emissions from fossil fuel combustion and cement production. Allen and Pavelsky used satellite imagery to estimate the surface area of rivers and streams (see the Perspective by Palmer and Ruhi). The stunning map that they generated results in an upward revision, by about one-third, to the total surface area of rivers and streams on Earth.

By George H. Allen, et al.

Aug 10th, 2018

Measuring Earths rivers

For the past 7 years, water crises have ranked among the top five global risks according to the World Economic Forum (2). The reason for this concern is that water is linked to environmental, societal, and economic risks—from biodiversity loss and ecosystem collapse to food crises, and from failures of urban planning to energy price shocks. Mitigating water-related risks to humans and ecosystems requires reliable accounting of freshwater resources. An essential first step is knowing where to find Earth’s fresh water. On page 585 of this issue, Allen and Pavelsky (3) make an important step in this direction by improving estimates of the global surface area of rivers using satellite observations.

By Margaret Palmer, et al.

Aug 8th, 2018