Boris Johnson will urge leaders of the world’s biggest economies to make good on their commitments to cut damaging carbon emissions ahead of crucial climate changes talks in Glasgow.
The Prime Minister is attending the G20 summit in Rome as key leaders gather in advance of the Cop26 conference, which formally opens on Monday.
Downing Street said he would be taking a tough message that as the countries which had done most to cause global warming, they now had to make themselves accountable to those nations experiencing the most severe consequences.
Speaking to reporters on his flight into the Italian capital, Mr Johnson said the fall of the Roman Empire showed how quickly civilisations could collapse if they failed to address fundamental issues.
“When things start to go wrong, they can go wrong at extraordinary speed,” he said.
“You saw that with the decline and fall of the Roman Empire and I’m afraid to say it’s true today, that unless we get this right in tackling climate change we could see our civilisation, our world, also go backwards.
“We could consign future generations to a life far less agreeable than our own. We could consign our children, our grandchildren, our great grandchildren, to a life where there are not only huge movements of populations, huge migrations, but also shortages of food, shortages of water, conflict, caused by climate change.
“There is absolutely no question this is a reality we must face up to.”
The Prime Minister’s official spokesman said that while more countries were now coming forward with commitments to net zero emissions, more needed to be done if they were to meet the goal set in the Paris Agreement of limiting global temperature increases to 1.5C.
“The success of Cop26 still hangs in the balance. Too many countries are doing too little,” the spokesman said.
“As the countries with the greatest historic and modern contributions to global warming who have built their economies on the backs of burning fossil fuels, G20 offers the key to unlocking global action and making progress we so badly need to live up to our commitments.
“While G20 countries are overwhelmingly responsible for the problem the poorer nations are already reaping the consequences.
“Climate-vulnerable countries are increasingly experiencing flooding, wild fires, heat waves and the prospect of their economies being devastated due to climate change.
“On Monday G20 leaders will come face-to-face with leaders from those countries at Cop26 and will have to account for their actions.
“If we don’t act now it will be too late.”
A number of key players, including China’s President Xi Jinping and Russia’s Vladimir Putin, have said they will not be attending either the G20 or Cop26, although they are expected to send delegations.
Mr Johnson had a lengthy telephone conversation with Mr Xi before leaving London on Friday in which he pressed the leader of the world’s biggest emitter to go further in reducing emissions – although it was unclear how much of an impact he was able to make.
The Prime Minister’s spokesman said was still important to keep making progress, insisting the UK was leading by example with the publication earlier this month of the world’s first comprehensive net zero strategy.
He said that if they were to succeed in reaching global net zero by the middle of the century it meant halving emissions by the end of the decade.
“What success looks like is ensuring that we have commitments sufficient to keep 1.5 alive,” the spokesman said.
“We need actual hard commitments from all countries if this going to be a success.
“This is an important moment to use this gathering of world leaders as we come to the final days before Cop to look them in the eye and make sure we are getting the level of action that is required to keep 1.5 alive.”
Mr Johnson will also meet in Rome with leaders of the US, Germany and France, to discuss efforts to revive the Iran nuclear deal.
“The Iran nuclear deal is the best option on the table for preventing Iran getting nuclear weapons.
“It is extremely important that Iran returns to compliance,” the Prime Minister’s spokesman said.