Environmentally friendly hydrogen gas fueled vehicles can dramatically reduce greenhouse gas emissions and lessen the country’s dependence on sources of fossil fuel.

Nitrogen oxides, the noxious byproduct of burning fossil fuels that can return to Earth in rain and snow as harmful nitrate, could taint urban water supplies and roadside waterways more than scientists and regulators realize, according to research published Oct. 20 in the online edition of the journal Environmental Science and Technology.

The global carbon cycle plays a vital role in climate change and is of intense importance to policy makers, but significant knowledge gaps remain in our understanding of it. Several scientists at the Envisat Symposium this week have highlighted research projects using ESA satellites to understand better this complex process.