You could call them the icebergs, largely hidden challenges that lie in wait for the second Obama administration. Like all of us, when it comes to priorities, the people in Washington assume that the thing that comes to mind first must be the most important. The recent crises or tensions with Afghanistan, Benghazi, and China make these feel like the whole story. But in fact they are really just a few chapters, and the ones we’re ignoring completely may actually have the most surprises in store.

If the administration wants to stay ahead of the game, here’s what it will need to spend more of its time and energy dealing with in the coming four years.

The eurozone. This is the least sexy, most important foreign policy issue facing America. The nations linked by the euro have started to split apart, with economies staying fairly strong in the north while others, including major economies like Italy and Spain, weakened to the point that they could go bankrupt. To save the euro, the continent’s stronger players might have to spend and borrow to untold levels to bail out its weaker ones. Or it could let them fail, and suffer a chain of collapses that will throw the entire continent, and possibly the world, into another, even longer recession. The debt crisis in Europe could make the American financial crisis of 2008 seem a minor contretemps by comparison.

Europe’s recovery needs to be managed, and that requires global cooperation and money.

Washington and China, along with the International Monetary Fund and the World Bank, will have to be closely involved, and that won’t happen without American leadership. Though the European crisis has already been a front-burner problem for two years, in the United States it barely cracks the public agenda except as a rhetorical bludgeon: “That guy wants to turn America into Greece!” But Europe’s importance to the global economy, and to America, is staggering: It’s the world’s largest economic bloc, worth $17 trillion, and it’s the US’s largest trading partner. If Europe goes down, we all go down.

Climate change. No politician likes to talk about climate change. It’s depressing news. It’s become highly partisan in this country, and it has no obvious solution even for those who understand the threat. It requires discussion of all kinds of hugely complex, dull-sounding science. When we do talk about it as a political issue, it’s largely as a domestic one: saving energy, dealing with the increasing fury and frequency of storms like Hurricane Sandy, investing in new infrastructure.

In fact, climate change is a massive foreign policy issue as well. On the preventive side, any emissions reduction requires cooperation across borders—between small numbers of powerful nations, like America and China, along with massive worldwide accords like the failed Kyoto Protocol. The responses will often need to be global as well. Rising oceans and temperatures have no regard for national boundaries, and most of the world’s population lives near soon-to-be-vulnerable coastlines. Entire cities might have to move, or be rebuilt, often across borders. Sandy could cost the American Northeast close to $100 billion when all is said and done (current damage estimates already top $50 billion). Imagine the price of climate-proofing the cities where most of the world lives—Mumbai, Shangahi, Lagos, Alexandria, and so on. Climate change, if unaddressed, could well become an American security issue, propelling unrest and failed states that will spur threats against the US.