The climate change envoy sacked by Boris Johnson has revealed the prime minister admitted he “doesn’t really get” the emergency the world faces, in a scathing attack.

The prime minister has also explored moving the crucial COP26 Glasgow summit in November to England because of “ballooning costs” and rows with the Scottish government, Claire Perry O’Neill said.

The former Tory energy minister said she suggested giving Nicola Sturgeon, the Scottish first minister, a key role, a proposal Mr Johnson rejected with “salty” language.

Lifting the lid on the apparent chaos, Ms Perry O’Neill said: “He has admitted to me he doesn’t really understand it [climate change] – he doesn’t really get it, I think is what he said.”

She warned the summit was being undermined by “playground politics” and was “hundreds of millions of pounds off track”, with just nine months to go.

And, following her sudden sacking as the summit’s president, she offered her “advice to anybody to whom Boris is making promises”.

“Get it in writing, get a lawyer to look at it – and make sure the money is in the bank,” Ms Perry O’Neill told BBC Radio 4’s Today programme.

COP26 is widely seen as the last realistic chance for countries to pledge the deep cuts in emissions to hold global heating to no more than 2C – and prevent catastrophic climate change.

Climate change: Decade's defining issue in pictures Show all 20 1 /20 Climate change: Decade's defining issue in pictures Climate change: Decade's defining issue in pictures California In this decade, humans have become ever more aware of climate change. Calls for leaders to act echo around the globe as the signs of a changing climate become ever more difficult to ignore Getty Climate change: Decade's defining issue in pictures Athens, Greece Fierce wildfires have flared up in numerous countries. The damage being caused is unprecedented: 103 people were killed in wildfires last year in California, one of the places best prepared, best equipped to fight such blazes in the world AFP/Getty Climate change: Decade's defining issue in pictures Redding, California Entire towns have been razed. The towns of Redding and Paradise in California were all but eliminated in the 2018 season AP Climate change: Decade's defining issue in pictures Athens, Greece While wildfires in Greece (pictured), Australia, Indonesia and many other countries have wrought chaos to infrastructure, economies and cost lives AFP/Getty Climate change: Decade's defining issue in pictures Carlisle, England In Britain, flooding has become commonplace. Extreme downpours in Carlisle in the winter of 2015 saw the previous record flood level being eclipsed by two feet AFP/Getty Climate change: Decade's defining issue in pictures Hebden Bridge, England Hebden Bridge in West Yorkshire has flooded repeatedly in the past decade, with the worst coming on Christmas Day 2015. Toby Smith of Climate Visuals, an organisation focused on improving how climate change is depicted in the media, says: "Extreme weather and flooding, has and will become more frequent due to climate change. An increase in the severity and distribution of press images, reports and media coverage across the nation has localised the issue. It has raised our emotions, perception and personalised the effects and hazards of climate change." Getty Climate change: Decade's defining issue in pictures Somerset, England Out west in Somerset, floods in 2013 led to entire villages being cut off and isolated for weeks Getty Climate change: Decade's defining issue in pictures Dumfries, Scotland "In summer 2012, intense rain flooded over 8000 properties. In 2013, storms and coastal surges combined catastrophically with elevated sea levels whilst December 2015, was the wettest month ever recorded. Major flooding events continued through the decade with the UK government declaring flooding as one of the nation's major threats in 2017," says Mr Smith of Climate Visuals Getty Climate change: Decade's defining issue in pictures London, England Weather has been more extreme in Britain in recent years. The 'Beast from the East' which arrived in February 2018 brought extraordinarily cold temperatures and high snowfall. Central London (pictured), where the city bustle tends to mean that snow doesn't even settle, was covered in inches of snow for day PA Climate change: Decade's defining issue in pictures London, England Months after the cold snap, a heatwave struck Britain, rendering the normally plush green of England's parks in Summer a parched brown for weeks AFP/Getty Climate change: Decade's defining issue in pictures New South Wales, Australia Worsening droughts in many countries have been disastrous for crop yields and have threatened livestock. In Australia, where a brutal drought persisted for months last year, farmers have suffered from mental health problems because of the threat to their livelihood Reuters Climate change: Decade's defining issue in pictures Tonle Sap, Cambodia Even dedicated climate skeptic Jeremy Clarkson has come to recognise the threat of climate change after visiting the Tonle Sap lake system in Cambodia. Over a million people rely on the water of Tonle Sap for work and sustinence but, as Mr Clarkson witnessed, a drought has severley depleted the water level Carlo Frem/Amazon Climate change: Decade's defining issue in pictures Addis Ababa, Ethiopia In reaction to these harbingers of climate obliteration, some humans have taken measures to counter the impending disaster. Ethiopia recently planted a reported 350 million trees in a single day AFP/Getty Climate change: Decade's defining issue in pictures Morocco Morocco has undertaken the most ambitious solar power scheme in the world, recently completing a solar plant the size of San Francisco AFP/Getty Climate change: Decade's defining issue in pictures London, England Electric cars are taking off as a viable alternative to fossil fuel burning vehicles and major cities across the world are adding charging points to accomodate AFP/Getty Climate change: Decade's defining issue in pictures Purmerend, The Netherlands Cities around the world are embracing cycling too, as a clean (and healthy) mode of transport. The Netherlands continues to lead the way with bikes far outnumbering people Jeroen Much/Andras Schuh Climate change: Decade's defining issue in pictures Xiamen, China Cycling infrastructure is taking over cities the world over, in the hope of reducing society's dependency on polluting vehicles Ma Weiwei Climate change: Decade's defining issue in pictures Chennai, India Despite positive steps being taken, humans continue to have a wildly adverse effect on the climate. There have been numerous major oil spills this decade, the most notable being the BP oil spill in the Gulf of Mexico in 2010 AFP/Getty Climate change: Decade's defining issue in pictures Amazon rainforest, Brazil More recently, large swathes of the Amazon rainforest were set alight by people to clear land for agriculture AFP/Getty Climate change: Decade's defining issue in pictures California This decade may have seen horrors but it has led to an understanding that the next decade must see change if human life is to continue Getty

But Ms Perry O’Neill said: “We are playing at a kind of Oxford United level when we need to be Liverpool if we are actually going to do what the world needs us to do.

And she said: “One of the things you would have hoped to have organised by now is an absolutely firm location.”

The Holyrood government bore some responsibility and had “behaved disgracefully” by setting aside some needed buildings for other purposes, she alleged.

In a letter to Mr Johnson, obtained by The Financial Times, Ms Perry O’Neill told him: “You promised to ‘lead from the front’ and asked me what was needed: ‘money, people, just tell us!’ Sadly these promises are not close to being met.”

She added: “This isn’t a pretty place to be and we owe the world a lot better.”

In his speech, the prime minister will pledge an earlier ban on new petrol and diesel vehicles – in 2035 rather than 2040 – as a measure to help achieve net-zero carbon emissions by 2050.

However, the move will still fall short of the call by his independent climate advisers to act by 2030.

“A new 2035 target will still leave the UK in the slow lane of the electric-car revolution and in the meantime allow more greenhouse gases to spew into the atmosphere,” said Friends of the Earth’s head of policy Mike Childs.