A group of environmental activists in northeast Texas say they have scaled 80-foot trees and are vowing to remain in an effort to block tree-clearing equipment that is making way for the controversial Keystone XL oil pipeline. On Monday, the eight protesters held a banner reading, “You Shall Not Pass,” and said they will remain in the way until the controversial pipeline is stopped for good. The action is the latest in a series of protests by pipeline opponents who say the project will poison local communities and damage the climate through increased greenhouse gases. The Keystone XL pipeline would carry oil from the Alberta tar sands to Gulf Coast refineries. President Obama has delayed a final decision on the pipeline until after the November election.