Astrobiology of Earth studies the fortuitous combination of numerous cosmic factors that together produced the special environment which enabled the emergence, persistence and evolution of life on our own planet, culminating in humanity. This environment has been subject to constant and chaotic change during life’s 3.6 billion year history. The geologically very recent appearance of humans and their effect on the biosphere is discussed in relation to its deterioration as well as climate change. The search for extraterrestrial life is considered with a view to the suggestion that humans may escape a depleted Earth by colonizing the universe.