At the halfway point to a climate gamble, 50 contributor ideas give just a taste of the creativity and innovation available to us

"One or other of us will have to go," Oscar Wilde is supposed to have said on his deathbed to the hated wallpaper in his room. The perilous acceleration of Arctic ice loss, and the imminent threat of irreversible climate change poses a similar ultimatum to the economic system that is pushing us over the brink. For society's sake I hope this time we redecorate.

Fortunately, many people are queuing up to propose better designs, rather than just cursing the interiors, as you can read about here.

Monday 1 October marks the halfway point in a 100-month countdown to a game of climate roulette.

On a very conservative estimate, 50 months from now, the dice become loaded against us in terms of keeping under a 2C temperature rise. This level matters because beyond it an environmental "domino effect" is likely to operate. In a volatile and unpredictable dynamic, things like melting ice, and the release of carbon from the planet's surface are set to feed off each other, accelerating and reinforcing the warming effect.

The time frame follows an estimate of risk of rising greenhouse gas concentrations from the world's leading authority on climate change, the Intergovernmental Panel on Climate Change (IPCC), that passed a certain point, it will no longer be "likely" that we stay the right side of the line. Some consider even a 2C rise too much, but it is the limit that the EU and others have signed up to.

Extraordinarily, however, in spite of the stakes, the issue has receded from the political frontline like a wave shrinking down a beach. This could, though, merely be a prelude to it returning with a vengeance. Politicians may have turned their backs, others have not.

Here's what a broad selection of groups and individuals who range from the Women's Institute to Oxfam and Margaret Thatcher's former environmental adviser, say in an open letter published in the Guardian today to the coalition government and opposition:

"This year has seen the record loss of sea ice, and greenhouse gas concentrations above the Arctic at their highest point for possibly 800,000 years. Crop-wrecking droughts and record temperatures have scorched the American Mid-West."

But, to our dismay, climate change and the weather volatility it fuels have fallen far down the political agenda when it needs to be at the top. It remains, however, one of the greatest threats to human progress, and tackling it is a huge economic opportunity

They call on both the coalition and Labour to spell out what they will do differently in the next 50 months to prevent a climate catastrophe.

Individually some go further. James Gustave Speth, the former head of the United Nations Development Programme appeals for mass, non-violent protest.

The climate scientist Prof Kevin Anderson says it is too late for rich countries to "grow" their way out of the problem and must find a new way to run their economies. He says everyone, including climate scientists, must reduce their emissions and he commits to lowering his own.

Barbara Stocking, chief executive of Oxfam also says it's time for lifestyle change in the wealthy world, especially if we are to tackle global poverty.

Sir Crispin Tickell, former UK permanent representative to the UN and the man credited with persuading Margaret Thatcher as prime inister to acknowledge and act on global warming, calls for a World Environment Organisation to simplify and make effective the wide range of international treaties and agreements.

Many more people describe the huge opportunities for economic recovery and better lives that could come from a great transition to a low-carbon, high well-being economy, but which are currently going begging.

Change is in the air, in spite of the current official blind spot and attempt to return to business as usual, or even go "backwards" as today's joint letter of concern warns. Why, for example, do we encourage the oil industry with tax breaks, when we know that to avoid runaway climate change we can only afford to burn around a fifth of the fossil fuels left in the ground, making it unburnable?

The ideas from our 50 contributors are just a taste of the creativity and innovation available. The failure to act "appears both reckless and short sighted" they write. Yet in the government, the situation appears to be like the old joke about the shopkeeper. When a customer asks for a new product, the shopkeeper replies, "No, sorry mate, people keep asking me for that and I keep telling them, there's just no call for it."

Whether it was rebuilding Europe after the second world war, or action to protect the ozone layer, we know it is possible to put aside narrow self-interest. Leadership like that goes down in history.

What we do in the next 50 months is not a choice between what we have done in the past and what we are doing today. It is an invitation to embark on the most extraordinary, exhilarating and challenging adventure our society has yet faced, learning how to thrive without disastrously destabilising the climate on which we depend. Every step matters, and it matters most that we start walking.

• 100 months and counting...