Read between the lines of the U.S. intelligence community’s quadrennial global trends report, a document released this week that has significant influence on White House thinking, and the message to President Obama is clear.

First, the United States is at a far more crucial juncture of human history than most Americans realize – reminiscent of 1815, 1918, 1945 and 1989. Second, the United States has something that is unprecedented among the world’s great powers, a second chance to shape the international economic and political system.

Read more deeply, and you’ll find a stark warning for the president within the National Intelligence Council’s 140-page “Global Trends 2030: Alternative Worlds” report.  The world may suffer severe consequences – ranging from economic slowdown and environmental catastrophe to violent conflict and global anarchy – if the U.S. fails to act, escape the fiscal cliff, restore its political effectiveness, revive its economic competitiveness, and engage China and a host of other rising actors.

The NIC lays out the stakes clearly for the U.S.:

How the U.S. evolves over the next 15-20 years – a big uncertainty – and whether the U.S. will be able to work with new partners to reinvent the international system will be among the most important variables in the future shape of the global order. Although the United States’ (and the West’s) relative decline vis-à-vis the rising states is inevitable, its future role in the international system is much harder to project: the degree to which the U.S. continues to dominate the international system could vary widely.

The challenge for U.S. leaders is that their margin of error is much smaller than it was after World War II. Then, America’s share of global GDP was 50% – more than twice what it is today. A mixture of post-war devastation and American economic and military dominance empowered the U.S. to construct, with friends and allies, a global institutional architecture that included the United Nations, the International Monetary Fund, the World Bank, the North Atlantic Treaty Organization and a host of others.