In addition to the shortage of water in some areas, there is the problem of rising water elsewhere. Senators Kerry and Feingold had an amendment to require all US government funded water projects - ie damns, brides, etc to consider the effect of global warming and to meet standards tougher than current regulations about being designed to handle anything less than a 100 year storm. The reason is that assuming a static situation with a known variance, there is an underlying trend - so something that happened only once in the last hundred years will happen with greater probability in the future.
As to sustainability, Kerry was working on that as long ago as the early 1990s. In fact, after Rio, he and Teresa Heinz were two of the people who started "Second Nature", designed so people in all related fields might learn the principles in college.
http://www.secondnature.org/AboutSN.html#History The Kerrys' book, This moment in Earth, clearly sees these issues.
The important thing here, is that Kerry has held hearings on the impact of this issue as a national security threat. He clearly has enlisted the support of many top ranked military on this and the enthusiastic support of former Senator Warner. (here's a link to that hearing -
http://foreign.senate.gov/hearings/2009/hrg090721p.html ) In addition, Kerry has gotten support of several top business people.
What is clear is that getting a bill out of the Senate will be tough. Unlike healthcare, reconciliation can't be used because the budget was not written in such a way as to get it. This also may signal it is less important to the President than healthcare is. However, it is clear that Senator Kerry is making a very powerful, multi prong case for not only getting something done - but doing it as well as possible given the politics.
In hearings and interviews, he has dispelled some Republican points.
1) He is writing in legislation that will strictly regulate the cap and trade market, disallowing things like derivatives. Now, Kerry was the one who wrote the legislation against international money laundering, investigated BCCI and was one of the good guys who investigated the savings and loan crisis.
2) Kerry has been in talks with the rest of the world, including China, for years. His comments on what China is doing and plannin to do show that they have made an enormous change over the last few years.