The three presidential debates covered a lot of ground. We heard about the budget deficit, about Medicare, about Libya. There were shout-outs to Big Bird, bayonets, and binders—even a brief discussion of the ongoing conflict in northern Mali.

Way to avoid all the important stuff.

Yet we couldn’t help but notice that there were five not-so-trivial policy issues that never even got mentioned once throughout the debating season. Here’s a list of what was missed:

1) The biggest weak spot in the domestic economy. The collapse of the housing market dragged the United States into recession, and it’s still holding back the recovery. Despite recent signs of life, we’ve still got a long way to go before construction, housing sales, and foreclosure rates return to their long-term averages. But you never would have guessed it listening to the debates: Both Romney and Obama mentioned housing only in passing.

2) The biggest weak spot in the global economy. For the past two years, the perpetual debt crisis in the euro zone has spooked financial markets and acted as a drag on the U.S. economy. Nothing against the conflict in Mali, but the average American’s life will be far more affected by whether, say, Germany ends up kicking Greece out of the currency union or not. And yet Europe never came up once. Which is too bad, because as Neil Irwin explains, the Obama administration has been heavily involved in the euro crisis, and there’s a record here worth dissecting.

3) The biggest environmental crisis facing the planet. If you ask Fatih Birol, head of the International Energy Agency, he’ll tell you that we’re now on pace to warm the planet 6°C by the end of the century. “Even schoolchildren know this will have catastrophic implications for all of us,” Birol said last year. Schoolchildren, maybe. But not the people running for president! For the first time since 1984, climate change didn’t get a single mention in the debates. (Even Lloyd Bentsen and Dan Quayle discussed it back in 1988.)

4) The most important appointments the next president will make. Federal Reserve Chairman Ben Bernanke’s term expires in 2014. That means the next president will decide whether to appoint a new chairman or, presuming Bernanke is open to it, reappoint the current one. Perhaps no single decision the next president will make will have as much influence on the economy. And yet the Federal Reserve—and monetary policy more generally—didn’t come up at any of the debates.

Moreover, four of the Supreme Court’s nine justices are over age 70. Currently, the court is divided on a 5-4 split, with conservatives holding a slight and unstable majority. If the next president has the opportunity to replace a justice from the other party, it could remake the balance of power on the court for a generation—and, in so doing, decide the fate of issues ranging from reproductive rights to campaign finance to the scope of federal power. And yet the Supreme Court never came up.

5) One of the biggest forces shaping our elections. This is the first election where both campaigns have refused public campaign financing, freeing them from the spending limits that come with them. The Supreme Court's decision in Citizens United also paved the way for individuals, corporations, and unions to make unlimited independent expenditures. Such changes have effectively dismantled key campaign finance reforms and given the richest individuals and organizations more leeway to shape the political landscape. But since both candidates benefit from the issue, neither was inclined to talk about it, and no moderator asked about it.

Runner-Up: The most important near-term policy difference between the candidates. Medicaid received four mentions during the three debates, so it wasn’t totally left out. But it got a whole lot less attention than Medicare, which was name-dropped 63 times by the two candidates. Missing the Medicaid discussion means we missed a debate over the biggest health care policy issue that divides the two candidates. While Obama and Romney plan to spend the exact same amount on Medicare for the foreseeable future, Romney wants to spend $1.7 trillion less on Medicaid. Here’s what that looks like in graph form, via the Incidental Economist:

The Kaiser Family Foundation estimates that between 31.3 and 37.6 million fewer Americans would qualify for Medicaid coverage under the budget that Romney has set. We know from new research that Medicaid saves lives. So this is a matter of life and death. But it barely got discussed.