Nationalism is the ideology of our age. No wonder the world is in crisis | Gordon Brown

As Rishi Sunak and Joe Biden meet world leaders at the G20, they should be pushing for greater cooperation to deal with growing threats

• Gordon Brown is the WHO ambassador for global health financing and was UK prime minister from 2007 to 2010

There is no longer such thing as the international community," a prominent African leader recently complained to me, lamenting that this week's G20 would, like September's UN general assembly, October's IMF-World Bank meetings and this month's Cop27, fail to combat the world's food, energy, debt, inflation, currency, pollution and poverty crises.

At the very moment the world needs to work together to address global problems that cannot be resolved without global solutions, it is being pulled apart not just by conflicts but also by a rising protectionism. And while it is not difficult to blame poor leadership, an outdated geopolitics is threatening a decade of perma-crises.

Gordon Brown is the WHO ambassador for global health financing and was UK prime minister from 2007 to 2010