The most comprehensive report ever on climate science was published today by the Intergovernmental Panel on Climate Change [1].

It’s the strongest ever statement that global warming is ‘unequivocal’.

Scientists are more certain than ever that human activity – mainly the burning of fossil fuels - is driving a powerful underlying trend of rising global temperatures.

Each of the last three decades has been successively warmer than any preceding decade since 1850.

The report also sets out the need for substantial and sustained reductions of greenhouse gas emissions in order to limit climate change.

And for the first time, it talks about the global carbon budget – the amount of carbon it’s safe to release into the atmosphere.

This echoes the recent reports from organisations such as Carbon Tracker that present a stark choice: if we want to avoid catastrophic climate change, we need to leave at least two thirds of existing fossil fuel reserves in the ground, unburned.

That choice is also an opportunity.

So what should we do?

There are some who suggest we still don’t know enough to act.

Who say they are concerned about the negative consequences of an overly ambitious response – developing a low carbon, safer, cleaner, healthier more biodiverse economy and creating thousands of jobs in the process too quickly.

But we must ask who they are.

All too often, they tend to have links to the fossil fuel industry - companies like Shell whose business plans rely on exploiting every last drop of oil and gas - regardless of the consequences for unique natural environments like the Arctic, for local people, or for our hopes of securing a safe and liveable climate.

If we want to avoid the worst, unmanageable impacts of climate change we need a rapid transition to renewables and a clean, secure, jobs rich, low carbon economy.

It’s a political choice whether we make that radical change, or whether we continue with business as usual.

Unicef this week warned that children in particular will be affected by the choices we make because they are especially vulnerable to the effects of global warming – on their health, wellbeing, livelihoods and survival.

They estimate that 25 million more children will suffer malnourishment because of climate change, with a further 100 million suffering food insecurity.

And yet young people’s voices and interests are often ignored in this important political debate.

Recently, groups like the UK Youth Climate Coalition have been making themselves heard, asking politicians: ‘how old will you be in 2050’ – calling for emissions to be cut at a much faster rate.

And there was a public and student outcry against the Coalition's plans to remove climate change from the curriculum.

Next month, People and Planet launch their “Fossil Free” divestment campaign in cities across the UK.

We need to give a voice to people who are most affected by the decisions taken today.

I know from my mail bag and email inbox that young people in Britain want a green industrial revolution – and they realise that what’s lacking is not technology, or capital, but political will.

 Responding to the IPCC report and the climate risks to our economy should be the political priority for politicians from all parties – it’s the only way we’ll leave a habitable planet for our children.

[1] you can read the IPCC’s two side summary for yourself here: http://www.climatechange2013.org/images/uploads/WG1AR5_Headlines.pdf