BOB: For the remainder of this hour we’ll be discussing climate change, literally the most urgent story in human history, yet one the press has struggled to address, how to understand all the science, much less explain it, what’s the right amount of advocacy. the most urgent story in human history, yet one the press has struggled to address. How to understand all the science much less explain it. What's the right amount of advocacy or of skepticism. When to point out political demagoguery on the subject. When to simply record and report the debate. And when to abandon any pretense of neutrality. For Alan Rusbridger outgoing editor of the Guardian after 20 years at the helm, the answer to the last question is now. In December he persuaded colleagues to launch a climate change campaign quickly before he has any regrets that he did not do enough. Here he is in a new Guardian podcast:

RUSBRIDGER: So in the New year i'd like a group of us to meet and brainstorming what exactly we can do to have the most effect. I want the focus to be narrow and forceful.

BOB: The ensuing campaign called Keep it in the Ground attempts to have a major impact leading to December's UN climate change conference in Paris. And more especially before a two degrees celsius further warming of the planet creates irreversible cataclysm. But he wishes to do this not by warning about atmospheric ruin, the Guardian's campaign is strictly market economics. Asking the two largest charitable foundations in the world - the Bill and Melinda Gates foundation and the Wellcome Trust - to divest their billions in fossil fuel investments. And there's a petition too. Because, says Rusbridger, reporting and even scolding have failed to generate enough urgency to save our world.

RUSBRIDGER: I think people feel helpless in the face of this story. they see governments finding it very hard to agree on action and I think they've stopped reading. So, one of the purposes starting the campaign was to give them something to do, and the reaction has been very very positive. We've had something like 170,000 people who have signed.

BOB: Alan, from your podcast called the biggest story in the world, here's a clip of the environmentalist and author Bill McKibben proposing a strategy --

MCKIBBON: A generation ago when the biggest moral issue was apartheid in South Africa, Nelson Mandela and Desmond Tutu suggested this tactic. That it was time the great institutions of the West to cut their economic ties with companies that propped up the apartheid regime. If there's ever gonna be any kind of international agreement it will only be because our political and business leaders are feeling unrelenting pressure from all over the world.

BOB: The Anti Apartheid model -- was that the aha moment for your team?

RUSBRIDGER: The common link is Desmond Tutu who is very involved in the divestment from fossil fuels campaign. McKibben has this protest movement called 350 dot org, has successfully moved the needle. He has persuaded some very big funds to divest and is creating movement in an area where otherwise we all have to sit back and wait for the political leaders to go to paris and do something, which they might or they might not, but i think they're unlikely to move unless they feel the hot wind of public interest on their necks.

BOB: Then there was the question of how many organizations to try to nudge to your way of thinking. And you opted for only two. Wellcome Trust and the Gates Foundation. What were those debates like?

RUSBRIDGER: This is not a hostile thing aimed at Gates or Welcome at all. They above all understand the health risks and scientific risks. And we thought it was more likely that they would listen to argument.

BOB: Although, no luck so far.

RUSBRIDGER: Well, the dialogue is literally a few weeks old at the moment. They say they disagree, Gates say they have an obligation to maximize their revenues, well we'll look at what kind of returns they're getting compared with what they would be getting if they weren't in fossil fuels and what kind of risks in the future they're willing to bear, and welcome our essentially saying it's better to engage with these companies. Well, we will press them for examples of what engagement looks like. I mean there's been one wind so far, which is that we realize that the moment we start writing about this people would look at the Guardian media group, that's the company which administers the Guardian on behalf of Scott Trust, and say what about your own investments --

BOB: Yeah, physician heal thyself --

RUSBRIDGER: Well quite. And I thought that was a fair point. I went to the Guardian media group before we started the campaign and said look you should know we're going to be writing about this, people will ask, and last week the Guardian media group decided that they were going to divest, and they said they weren't doing that on moral grounds, they said that they were doing that on hard headed business grounds.

BOB: that fossil fuel assets will eventually become unusable and therefore worthless, so it's not just scientists crying run for your lives, you're saying to investors, run for YOUR lives.

RUSBRIDGER: There's simply too much fossil fuels in the world. We can't safely burn it and stay within the two degrees which everyone agrees is the outer limit of what we can allow. And so this stuff can never be burned. And I think once the penny drops with the people who control funds, they will want to not be part of an earning class of stranded assets. They will want to get rid of it. I think it's interesting that people like the Governor of the bank of England and the head of the World Bank are beginning to wave a big red flag about what they see as a likely bubble and this would be a bubble like no other bubble that we've experienced before. If humanity is to act, it's better that it acts sooner, because the cost of acting later is going to be exponentially greater. it may not win quickly in the time I'm editor, but I'm sure this battle to keep it in the ground will be won.

BOB: Do you have any evidence that the public is tuned out on this, as you call it, biggest story in the world? Have the forces of climate denial managed to turn this not into a scientific question but a political one, forcing citizens to just tune out the usual suspects on one side saying one thing, and the supposed skeptics on the other side saying another thing, and everybody just goes back to business as usual.

RUSBRIDGER: Anecdotally speaking to a lot of journalists not on the Guardian but on other news organizations they've admitted privately that they haven't given up on it, of course, they go on reporting it, but they find it very difficult to find new ways of animating. There are only so many pictures of polar bears on ice caps that you can use. I think finding a way of people sitting up and taking notice is a perfectly valid journalistic thing. when the science is really so settled, that is sufficiently beyond any reasonable doubt that it seems to me there's no point in arguing about that, we might move straight on to the political and economic consequences and possibilities of doing something about it.

ROB: Alan, thank you.

RUSBRIDGER: Thank you very much.

BOB: Alan Rusbridger is the editor of the Guardian. Its campaign to push the Gates Foundation and Wellcome Trust to divest from Fossil fuels is called keep it in the ground.