The climate became damaged beyond repair, and not everyone wanted to live in it. Like everything else, the altered meteorologic conditions, known as the Shift, created a society of protected enclaves, and sociopaths surviving out in the charred remains of western North America.
The temperate rainforests of the Pacific Northwest were dying, and scientists rushed to grow trees that could survive in this new semi-arid environment. They scavenged the western forests for the hardiest seeds and grew them in a massive nursery complex. During that time, something amazing happened, the trees began to send signals to humans, and scientists rushed to decipher them. Were they omens? A great evolutionary leap forward? No one was quite certain. Extinction loomed. Perhaps the arbors recognized that Homo sapiens were not only their nemesis, but their last hope. Millions of years of evolutionary history gave way and the trees revealed their secrets. The magnitude of this communication changed everything.
The anti-science armies would have none of it; they moved across the West like a locust swarm, convinced of their divine mission. They destroyed the last vestiges of learning including the research institutes and the universities. The Shift created societal upheaval, and inflicted deep scars on the landscape, but there was a flicker of hope...the trees.