A Greek exit from the eurozone would make the country the poster child of what the political scientist Ian Bremmer has dubbed the “G-zero world.”

Bremmer in his recent book Every Nation for Itself: Winners and Losers in a G-Zero World (2012) argues that Europe and the United States can no longer set the global economic and political agenda. The ongoing battle to bolster the eurozone will discourage European leaders from searching abroad for new ways to extend the influence of their governments while leading developing states face too many challenges both at home and in their immediate neighborhoods to embrace the risks and burdens that come with a larger share of global leadership.

We now live in a world without global leadership. The need to prevent conflict, grow the global economy, manage growing demand for energy, implement far sighted trade and investment policies and counter transnational risks to public health demands leaders who are willing and able to shoulder burdens and enforce compromise.

Bremmer’s argument particularly applies to Greece. If it leaves the single currency area, it will be a point of no return for Greece.

Nations that have historically been considered middle powers, including Canada, Japan and Norway, always had partners to assist in their development. Canada could long depend on the United Kingdom for security and trade relations. Norway shares common cultural influences with neighboring Sweden and despite animosity in the past, has little to fear in Scandinavia in terms of security.

But what of European and its heavily indebted peripheral countries? Let’s compare Ireland and Portugal in terms of cultural affinity and alliance building blocks.

Ireland is an integral part of the English-speaking world. Britain and the United States are reliable partners in terms of investment and security partnerships. Large American companies like Google, Intel, Microsoft and Pfizer have holdings in Ireland. Both larger countries could save Ireland from disaster.

Portugal, too, could have an ally. Its former colony Brazil is now the dominant force in the Lusophone world. Leaving aside overblown expectations and sometimes feisty rhetoric, commercial and cultural relations between Brazil and Portugal have never been stronger since the former gained independence in 1821–1823.

The Greek case is very different. If it leaves the eurozone, it would be an international pariah, a country literally in ruins, divided politically, with no real productive base, unable or unwilling to implement the sort of reforms that are necessary if a state is to compete in the twenty-first century.

Greece would be the ultimate example of the G-zero world. Having enjoyed the progress and stability that came with the economic and security order of the American century, it would be reduced in terms of affluence to the likes of Ghana and Kazakhstan.

Most worrying is that Greece could also be left without allies. There are no other Greek-speaking countries besides Cyprus and that island it has to share in terms of influence with the Turks. It has no major trading partners outside of the European Union.

Outside of the euro, Greece would be in no position to build profitable commercial and security relationships with other partners without becoming overly reliant on any one of them.