Over the course of the first three decades of the 21st the global climate began to experience a more rapid shift than it had in previous centuries. Stimulated by greenhouse gas emissions from human civilization over the course of the Petroleum Age that accelerated the natural warming cycles of the Earth, by the 2020s the Arctic circle was Ice Free year round, and the Greenland Ice Sheet had become extremely unstable. From the mid 2020s to the 2070s global weather patterns entered into a period of extreme instability where seasonal temperature extremes reached at times deadly levels.
While millions were driven from their homes by Climate Change a number of civil engineering projects around the world did succeed in mitigating the damage over the long term. The most notable of these were the great sea walls constructed around major inlets and river mouths. The largest of these sea walls is Brazil's Amazon Gateway, a massive structure that limits the flow of water into the mouth of the Amazon River. This project is widely attributed to the survival of the Amazon rainforest, and to a greater extent the global ecology. Similar sea walls were built to guard the mouth of the Mississippi River, the Ganges, and the Yellow River. The Three Gorges Damn that was reconstructed in 2040 also acts as a sea wall for the greater Yangtze Basin.
The Climate Shift caused the largest mass extinction in human history, resulting in the die off of an estimated 300,000 unique species; most of which were insects, birds, and aquatic life. While the Genetic Vault managed to keep a file of the known species that died off during this period, many have argued that the damage done to the environment cannot be undone.