Population growth and agriculture
There is no population bomb as the number of new babies is stable around the world. There is rather an ageing population, leading to 11 billions by the end of the century, with the migration to mega-cities increasing.
The demand for food as well as energy will grow inevitably from such a population increase.
Fields for for crops will compete with fields for global warming mitigation, such as forest to suck CO2 from the atmosphere.
High-tech for more food (e.g., GMOs, vertical farming…) and for building high mega-cities to save fields from sprawling cities will be even more critical.