What are the most important three or four density-dependent limiting factors that are likely to affect growth of the world human population?

Answer:Energy Supply

When the population becomes dense in one place the demand of energy resources increase which affect the population negatively.

For example, if a few number of monkeys were to inhabit an area, chances are that food demand wouldn't be such a pressing issue. So if the density of the population increases so does the competition for food supply and the chances of depleting their food sources also increases.

Predation: The Balance of Hunter & Hunted

In some cases imbalances in predator-prey relationships create density-dependent limiting factors. A reduction in the number of jackrabbits in one area of Death Valley could result in less available food for the local coyote population, demanding an adjustment - whether coyote mortality or dispersal elsewhere.

Competition Among Species

Competition between species for food may serve as a density-dependent limiting factor when at least one of two populations reaches a density where the two populations combined overwhelm the food supply. For example, when rainbow smelt were introduced into Lake Winnipeg, they put a strain on the flourishing population of emerald shiners because both species eat the same food. This competition likely explains the resulting decrease in emerald shiners. Also, competition isn't limited to animals. Eurasian water milfoil is a freshwater aquatic plant that grows and spreads rapidly in ponds and lakes. It can use up much of the dissolved oxygen that other plants and fish need to survive.

Disease: A Peril for Dense Populations

Disease can be density-dependent because organisms have to live close enough to one another for the disease to spread. In the context of humanity, it is easier to see how disease can spread in a city such as New York or Hong Kong as opposed to the rural setting of Wyoming. Research conducted at the Ohio State University shows a link between population density and higher percentages of water-borne illnesses. This shouldn't be a surprise, as many high-population areas utilize integrated city water systems while many rural areas still use individual wells. The denser population creates the need for a community water supply, which then serves as a transport for pathogens.