Ideas festivals are having a moment. These days, few things lure us away from our laptop screens like the promise of a speaker with a life-changing perspective, or a TED talk that you can embrace with evangelical zeal.

The Festival of Dangerous Ideas in Sydney – which is co-hosted by the St James Ethics Centre and the Sydney Opera House, and which has featured lectures by Julian Assange, Germaine Greer and Dan Savage – has seen its audience triple since it launched in 2009. It will again this year include a Melbourne component.

The 2015 festival is partnering with the Melbourne Writers Festival, a web series and an online magazine published on US website Medium. “Although we obviously want to talk about events that are important to audiences in Australia, it’s important to engage with trends and events that are happening around the world. We’re also trying to capture some ideas that people are just on the cusp of getting interested in.”

This year’s festival, which includes panels and solo sessions from British journalist Tariq Ali and activist Naomi Klein, continues the event’s focus on left-field thinking and radical ideas. Curator Ann Mossop says she’s particularly excited to see Klein, whose seminal book No Logo (2000) is still the definitive manifesto for anti-consumerism.

“We’re really thrilled Naomi Klein is coming. Her whole argument is a really dangerous one, but she’s also a really brilliant and compelling speaker,” says Mossop.

Here are our picks:

Capitalism and the Climate – Naomi Klein
For Naomi Klein, the climate-change debate isn’t about simplistic arguments but about how our ecosystem and economic system are fundamentally incompatible. During this session, Klein will explore the ways in which climate change is shaped by capitalism’s failures, and prove that confronting this crisis can create space for radical change.

The Twilight of Democracy – Tariq Ali
What is the purpose of democracy when it’s become more challenging than ever to tell the left and right apart? Tariq Ali, a celebrated journalist and filmmaker who has been voicing the concerns of the left since the 1960s, discusses the failure of Western democracy when parties give in to the whims of the market.

Nuclear Delussions – Eric Schlosser
We’ve known how to build nuclear weapons for a long time, so why can’t we work out how to keep them safe? Investigative journalist, Eric Schlosser’s book Command and Control (2013), examines the efforts of the military to prevent nuclear weapons from being stolen, sabotaged or detonated by accident. Previous books by Schlosser include Fast Food Nation (2001), and Reefer Madness (2003).

The Festival of Dangerous Ideas is on September 5–6 at the Sydney Opera House. The Melbourne Writer's Festival runs from August 20-30.