Greenpeace USA climbers form a blockade on the Fred Hartman Bridge in Baytown, Texas shutting down the largest fossil fuel thoroughfare in the United States ahead of the third Democratic primary debate in nearby Houston. The climbers are preventing the transport of all oil and gas through the Houston Ship Channel, home to the largest petrochemical complex in the United States. Their action is a call to the country's present and future leaders to imagine a world beyond fossil fuels and embrace a just transition to renewable energy.