The NAE put together a committee of scientists, visionary thinkers and engineers and asked them to identify the 14 great engineering challenges that will face humanity in the 21st century. The committee was composed of such luminaries as Larry Page, co-founder of Google, Raymond Kurzweil, author of The Singularity is Near, Professors from Princeton, MIT, Stanford, and other major centers of learning, as well as renowned scientists in fields as diverse as nanotech to urban planning.

The list is at once elementary and incisive, and the benefit in reading about each item is not in learning that we need to deal with the excess carbon dioxide in our atmosphere, for example, but rather what we have done thus far, what the immediate technical problems are, and what plans and efforts to deal with it are already underway.

Sample items include needing to harvest the energy of the sun; reverse engineer the brain; restore and improve urban infrastructure; and secure cyberspace. There are 14 in all, and each is well worth the read, from the fun essay on the future of virtual reality to the less glamorous need to salvage the nitrogen cycle.
So go over there, and take a look!