In-atmosphere Travel is Increasing Safely

The number of fatal accidents with jet planes in commercial airlines has continued to decrease down to 0.42 per 1 million flights, which is almost down 60% compared to 30 years ago.
These figures do not include the out-of-atmosphere traveling that continues to increase every year, and is mainly counted by number of passengers that are going by space shuttles out of the atmosphere, than by kilometres.
Argument: Since the world's population in the developed countries will not increase until 2040 according to United Nations, the annual growth rate in passenger kilometers will decrease compared to the last 40 years. Out of the atmosphere travel will be available around 2012 (apart from the few "tourists" that have been away so far).
Questions: 3.5% of the human-induced global warming originated from aviation according to the Intergovernmental Panel on Climate Change (IPCC). What fuel will be the common one in 2040, oil, alcohol, hydrogen, biodiesel, or a combination?