According to the prophets (aka Writers on the tv series Sliders), biological warfare will devastate the earth, and Australia will rise as the sole super power.
Love Gods - Sliders Wiki, a database for Sliders the television series that anyone can edit
The Earth's population will be forced to eat Vegemite and consume Australian beer at every meal. They will be forced to adopt quirky sayings that Australia thinks are theirs (but really that stuff is said and done elsewhere). All popular Actors from new Zealand will have their histories re-written to be Australian. Any actors gone bad will be shipped to the hippy penalty colonies of New Zealand and forced to eat only Fush and Chups.
Love Gods - Sliders Wiki, a database for Sliders the television series that anyone can edit
Iraq released a virus in the 1980's which attacked the Y Chromosome (ironically eliminating the male population of Iraq), which went on to kill most of the male population of that world (the survivors had natural immunity to it), so the governments of the world, decided to put all their remaining men in "Breeding centres" to protect them from other governments and to protect them from mobs of women as they are in a race to repopulate, the men are then forced to mate with 5-7 women a day, some who escape go to Mexico which has no forced breeding. Australia was the furthest away from the virus to suffer the fewest casulities (starting with over 1100 men), so Australia and the US are more antagonistic towards each other.