We're not overpopulated. 

We have over 50,000 acres of ag land NOT in the urban core on Oahu to farm for food.  We have the ocean to desalinate for water. And we have enormous renewable energy resources. 

The big threat is not over population but climate change. We may have to set up a huge sea wall from Hawaii Kai to Waianae before the end of the century. 

My guess is that China, being the largest economy in the next 10 years, will become impatient at American self denial and begin geo-engineering the world climate. Trump's "we'll-see decisions" will not satisfy the world and China.