Climate activists demonstrating to coincide with the 2019 U.N. Climate Action Summit blocked intersections and snarled morning-commute traffic across Washington, D.C., Monday morning as they called on officials to take action on global warming. The group, called "Shut Down D.C.," has planned a week of activities to bring attention to climate change and convince national and international leaders to act. Monday's continuation of the "Global Climate Strike" follows worldwide climate protests on Friday, including a demonstration in New York City led by Swedish teenager Greta Thunberg.