I. INTRODUCTION II. WESTERN WATER PROJECTS ARE HIGHLY VULNERABLE TO GLOBAL WARMING III. ADAPTATION WILL BE DIFFICULT, AT BEST A. Infrastructure constraints B. Institutional constraints IV. THE APPEAL OF STABILITY V. BARRIERS TO REDISTRIBUTING WATER VI. INSTITUTIONAL BARRIERS TO CHANGING PROJECT OPERATIONS VII. COURTING TRAIN WRECKS VIII. CAN CREATURES WHO CRAVE STABILITY DEAL WITH CHANGE? IX. CONCLUSION I. INTRODUCTION The premise of this climate change symposium is one whose importance the legal community in the United States has been slow to understand. There is wide agreement among climate scientists that global climate change calls for two distinct types of response. The first is a reduction in the amount and rate of greenhouse gas emissions, so as to slow increases in global temperatures and limit the impacts of associated climatic shifts. This response has attracted much attention from lawyers and economists. They have sought to force policy shifts through litigation, opined about the pros and cons of various policy designs, and purported to forecast the economic and social impacts of various strategies. The second response, which has received much less attention, is adaptation. Among some climate scientists, talk of adaptation has been almost taboo for fear that it might be seen as a substitute for aggressive emission reduction measures. (1) Although lawyers may not see discussion of adaptation as taboo, until very recently they have not been much interested in it. Perhaps adaptation seems less glamorous than devising new schemes to regulate carbon dioxide emissions, perhaps it seems too difficult, or perhaps it is seen as potentially undermining the impulses toward environmental protection that provide the conceptual and political foundation for environmental law. (2) Difficult and unappealing as it may be, however, there can be no doubt that we need to confront adaptation. No matter how quickly and how aggressively we act to rein in future emissions, the profligate consumption of fossil fuels since the industrial revolution has already irrevocably committed the globe to substantial climatic changes. (3) Dealing with those changes will pose substantial challenges, requiring that we embrace flexibility and dynamism in a way that does not come naturally to law, to our institutions, or - for that matter - to human nature. Drawing upon the history of water distribution in the arid American west, this article offers a cautionary lesson about the difficulties of meeting the challenge of climate change. While there are some hopeful signs, no one should underestimate the barriers, or the need for lawyers and legal academics to devote continued attention and energy to the task of adapting to those aspects of climate change that cannot be mitigated. II. WESTERN WATER PROJECTS ARE HIGHLY VULNERABLE TO GLOBAL WARMING In California, 36 million people depend upon a Mediterranean climate characterized by three important features. First, precipitation is highly seasonal. Rain and snow are almost entirely confined to the winter months, which is great for barbecuing but not ideal for growing crops or even lawns. While 80% of the precipitation in California occurs between October and March, about 75% of the water use occurs between April and September. Second, annual precipitation is highly variable. Both floods and droughts are common. Odd as it sounds, average water years are rare. (4) Third, the precipitation is geographically separated from the demand for water. Average precipitation varies by an order of magnitude, from less than 12 inches to more than 120 inches per year across the state. Both population centers and key agricultural districts are concentrated in relatively dry areas. About two-thirds of all precipitation in California falls to the north of Sacramento, while about two thirds of all the water use occurs to the south. …