One month ago, on a bright, sunny morning, I sat in a central London office listening to a presentation by some of Britain’s best minds on the science of the world’s impending climate disaster.

They spoke passionately and authoritatively as they set out in no uncertain terms quite how urgently the emergency needs tackling.

They were the government’s own advisers, members of the Committee on Climate Change, and they were issuing what was the most serious warning yet for British policy-makers on the future for us all. They offered detailed analysis of exactly how the UK could – and should – eliminate all damaging emissions by 2050.

The price of inaction was unthinkable, they said – and far, far higher than the cost of action.

Just four days later the UN published a report on the latest research on biodiversity and the findings were alarming. It said that wildlife is being destroyed at an unprecedented rate, with a million species facing extinction unless world leaders introduce drastic changes.

Thousands of mothers stage climate protest in London Show all 8 1 /8 Thousands of mothers stage climate protest in London Thousands of mothers stage climate protest in London Protesters bring placards as they gather for a march calling for action to combat climate change organised by the climate campaign group Mothers Rise Up in central London AFP/Getty Images Thousands of mothers stage climate protest in London Protesters bring placards as they gather for a march calling for action to combat climate change organised by the climate campaign group Mothers Rise Up in central London AFP/Getty Images Thousands of mothers stage climate protest in London Activists take part in an Extinction Rebellion climate change march on International Mothers' Day in London REUTERS Thousands of mothers stage climate protest in London Protesters bring placards as they gather for a march calling for action to combat climate change organised by the climate campaign group Mothers Rise Up in central London AFP/Getty Images Thousands of mothers stage climate protest in London Protesters bring placards as they gather for a march calling for action to combat climate change organised by the climate campaign group Mothers Rise Up in central London AFP/Getty Images Thousands of mothers stage climate protest in London An activist takes part in an Extinction Rebellion climate change march on International Mothers' Day in London REUTERS Thousands of mothers stage climate protest in London Activists take part in an Extinction Rebellion climate change march on International Mothers' Day in London REUTERS Thousands of mothers stage climate protest in London Activists take part in an Extinction Rebellion climate change march on International Mothers' Day in London REUTERS

Humans are putting our own future at risk by harming the very systems we rely on. Our inaction is undermining efforts to tackle poverty, to improve health and to curb climate change, the scientists said.

And this week we have seen a prediction that human civilisation itself could end within decades if we fail to take collective action to stop temperatures reaching 3C above pre-industrial levels. The report, co-written by a former oil and gas executive, suggests the world is ignoring plausible scenarios that would have devastating consequences.

At last, you might think, world leaders and decision-makers will no longer be able to ignore the science and the advice, given the expertise and stature of those sounding the alarm and the extent of the research.

Together, these reports have formed probably the greatest plea the world has ever had to tackle the twin emergencies facing our planet and everything alive on it. The authors have warned there is no time to lose.

I’m prepared to be disappointed.

Perhaps I’m being impatient, but we are a month on from that original Committee on Climate Change warning, and I have not seen a single tangible announcement or commitment in response from those with the power to act.

I understand why most people, especially those of us who are non-scientists, start to switch off when warnings on extinction and climate disaster are produced. They seem too apocalyptic, too nebulous, too distant to comprehend. And most “normal” people feel they can’t do much about it, anyway.

But if world leaders, policymakers and advisers are not scurrying behind the scenes to take action after hearing the compelling evidence about how we are sleepwalking towards catastrophe, it will be a scandal.

Eight months ago, the world’s leading climate scientists – the IPCC – warned that humanity has only 12 years left in which to cap temperature rises at 1.5C or face a sharply higher risk of drought, floods and heatwaves.

So the latest glut of evidence will hardly have come as a surprise.

The UN said last week that 80 countries want to improve their pledges made under the 2015 Paris climate deal to cap temperature rises at 2C, which sounds like good news. But they are nowhere near meeting the original pledges, which still leaves the world at risk of climate chaos anyway.

What is required are wholesale transformations in how we use, take from and dump back onto the Earth and its ecosystems.

The solutions have been offered on a plate.

But which countries have announced they are ending sales of diesel and petrol vehicles within five years? Which are seriously ramping up renewable energy sources to outweigh coal and gas? Which government is introducing a tax on meat and dairy? Where are the big new disincentives for flying?

It seems national visions are nowhere near ambitious enough or urgent enough.

The UK environment department has announced a mass planting of urban trees and the creation of 41 new marine conservation zones, but these are meagre measures when, as has been reported, the chancellor Philip Hammond has decided to reject the Climate Change Committee’s advice.

Britain has also allowed itself to exploit previous “overperformance” on climate targets to relax limits in the future. These are not the actions of a “world leader” on climate.

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Britain is one of the most nature-depleted countries and still one of the most influential. The onus is on us to be a genuine pioneer in revolutionising our food, transport and power systems, as well as our reliance on fossil fuels.

The UN experts warned a month ago that wildlife was vanishing so quickly that no country could afford a business-as-usual approach.

Yet indulging in business as usual is exactly what appears to be happening, our leaders sleepwalking – dragging us with them – towards an unparalleled catastrophe. Perhaps they consider the short-term financial cost a vote-loser, even if the rise of the Green Party in the recent European elections might help temper that assumption.