Most of the world still looks empty. A second glance and you realize why. Only about a quarter of the land is good for farming. Empty areas of the planet are empty for good reason. That can change, and is already changing.
Sunlight is available everywhere, regardless of how high or cold the land.
Plants are remarkably efficient factories for converting sunlight, water, and carbon dioxide into food. By genetic engineering, we are producing new crop varieties with shorter growing seasons and more tolerance of cold, drought and high salinity. In the future, it seems certain that areas of the globe now empty will be able to fill with high-yield food crops, and then with people. According to projections, they will have to. Population estimates for the year 2050 range from eight to twelve billion, for 2100 from ten to fifteen billion.