Over 20 Greenpeace protesters have blockaded a major bridge spanning the Houston Ship Channel ahead of Thursday night's Democratic debate in the city. Photos showed protesters dangling over the edge of Fred Hartman Bridge between Baytown and La Porte. Local network ABC13 reports that the protesters have said they will stay suspended from the bridge for 24 hours to prevent the transport of any oil and gas through the channel, adding that they want the protests to act as a call to the Democratic candidates to imagine a world without fossil fuels. The Coast Guard reportedly said part of the Houston Ship Channel has been closed due to the activists suspended from the bridge.