Editors call it 'eat-your-peas' journalism — stories that are really good for you, if not nearly as enjoyable as the latest news about Jeremy Clarkson or the wardrobe malfunction of a breakfast television presenter.

Climate change is the ultimate eat-your-peas journalism. On some level, most people are aware that they should be deeply concerned about it. On another level, they just aren't. Perhaps it is just too frightening to think about. The story changes little from day to day. And, anyway, there seems to be little that anyone can do about it. A depressing fatalism settles over the subject. News editors shrug and change the subject.

But what if the climate story is the most important news on Earth — in the sense that, if we can't find a solution, then our children and grandchildren may well inherit a planet that is deeply hostile to the sort of civilization we enjoy?

I pondered this question at home over Christmas. I had been editing The Guardian for nearly 20 years and had announced that I would step down in the summer of 2015. Was there — in my time still left as editor — the opportunity to do something sharp and focused about climate change? Something that would make people wolf down their peas with relish?

I had in my mind the words of the US writer and environmental campaigner Bill McKibben: this thing has moved beyond the environment pages. The scientists and ecologists have done brilliant work over the years, but the essentials are now settled. The climate story has moved into the realms of politics, finance and economics. That is how you would have to write the story to make an impact.

Newspaper campaigns can energize and inspire people in a way that simple reporting sometimes does not. The Guardian toyed with the idea of aiming such a campaign at policy-makers, but that felt more like eating broccoli. It would have been easy, but probably not effective, to aim at the big, bad and familiar targets in the fossil-fuel industries.

McKibben convinced us to focus on the three numbers that could determine the future of our species. The first, 2 °C, is the internationally agreed warming threshold for dangerous climate-change impacts. The second figure is the amount of extra carbon dioxide emissions that are likely to push us over that threshold. The final figure is the amount of carbon dioxide that would be produced if all of the known fossil-fuel reserves in the world were extracted and burned.

“Some protest that divesting from fossil fuels will simply lead to 'bad' money replacing 'Good'.”

There is, of course, uncertainty around these numbers. And as we burn fossil fuels ever faster they present a moving target. But what is very clear is that the third figure is much higher than the second — three to five times higher, in fact. Therefore the majority of the oil, gas and coal reserves can never be allowed to be dug up. And fossil-fuel companies should not waste investor capital prospecting for more such reserves.

Companies with these reserves are almost certainly vastly over-valued, and this is dawning on a great many people — from central bankers to investment-fund managers, faith leaders, chief executives, universities and non-governmental organizations.

But not everyone agrees on how to respond. Some protest that divesting from fossil fuels will simply lead to 'bad' money replacing 'good'. Or that they have a duty to maximize returns. Or that keeping money in these companies enables 'good' people to 'engage' and have some influence.

Somewhat surprisingly, there are some 'good' organizations that have so far declined to move their money out of oil, gas and coal. There are few better foundations in the fields of science and medicine than the Bill & Melinda Gates Foundation and the Wellcome Trust. They give away huge amounts of money to projects and research that save countless lives and advance human knowledge and understanding. There is almost nothing not to like about them.

But neither foundation will take their money out of the companies that cannot be allowed to extract and burn all the hydrocarbons they own.

And so, as part of our campaign, Keep it in the Ground, we have asked these organizations — politely and respectfully, but with determination — to think again. More than 180,000 readers have signed a petition asking them to reconsider. And, if you were about to ask, the Guardian Media Group has, in the space of two months, moved from not really thinking very much about the issue to announcing that its £800-million (US$1.2-billion) fund will divest from fossil fuels within 2–5 years.

Wellcome's excuse — that it prefers to “engage” with the fossil-fuel giants — sounds feeble. It has not produced any evidence of tangible gains from the strategy. If Wellcome can genuinely point to the fruits of engagement, it should surely — like good scientists — demonstrate the evidence, not hide behind commercial confidentiality.

Likewise, if the Gates wants to demonstrate that the good it does outweighs the harmful activities it helps to fund, it should come out and make that case public.

In the absence of such evidence, these wonderful progressive foundations are failing to show the kind of leadership that could be transformative in shifting policy arguments and influencing others. The voices that will resonate loudest with the Wellcome and the Gates are those of scientists. I urge you to make them heard.