There are more than seven billion people alive on the earth today. In my lifetime, which is not even a feather of recorded history, the population of humans on this planet has increased by threefold. The population has increased six fold since my grandfather was born and nearly fourfold since my father was born.
There are many parts of the world filled by humanity, and even more filled by the activities of humanity. For the time being, but only for the time being, earth is room enough, but a threefold increase in population on this planet over the next sixty or seventy years will leave us all with less room to live and fewer resources to share. There will be little living space. Then earth will not be room enough.
Of course, the population increases of the past are no measure for future population increases. It is perfectly possible that our planet will need to cleanse itself of much of the humanity that would otherwise infect it, and nature has powerful cleansing tools. Some, such as disease and plagues, have previously been used, but perhaps the most powerful cleansing tool is being built by humanity, slowly surely and carefully without realising that it is doing so. it is a tool that melts ice caps and warms the surface cleaning a significant amount of the dirt and debris, like a good disinfectant.